PEOPLE@HES-SO Directory and Skills inventory

Hydrolienne pour canaux artificiels Centrale de Lavey - OFEN SI/501323-01 et The Ark 715-03

Role: Main Applicant

Financement: HES-SO Rectorat; VS - Institut Systèmes industriels; CTI; VS - Institut Systèmes industriels

Description du projet : The Swiss Competence Center on Supply of Electricity (SCCER-SoE) has been established in November 2013 to develop fundamental research and innovative solutions in the domains of GeoEnergies (Deep Geothermal Energy and CO2 sequestration) and HydroPower. In its first two years of implementation, SCCER-SoE has built a true national competence center, with research and cooperation partners from the ETH schools and research centers, six Universities, three UAS, key industry partners, federal offices and services. The SCCER-SoE focus has been on sustainable competence expansion, by establishing new professorships and research positions, on international cooperation, on building new technology platforms, laboratories and testing facilities, on working with industry to design 10-year roadmaps for Deep-Geothermal Energy, Carbon Capture and Sequestration and Hydro-power, aiming at delivering substantial progress towards meeting the challenges of the Energy Strategy 2050. In Phase II, 2017-2020, the SCCER-SoE will continue with the implementation of the innovation roadmaps, the development of integrative solutions, testing and installation of innovative technologies, technology assessment and scenario modelling. It will expand the focus on pilot and demonstration projects, conducted with industry partners, to validate the technologies and proposed solutions; seven pilot and demonstration projects will be pursued in Phase II, covering the whole portfolio of technologies and energy sources of SCCER-SoE.

, , , , , , , , , , , , , , , , , , , , , Research team within HES-SO: Steiner Amandus Walpen Olivier Vaccari Aldo Münch-Alligné Cécile Gallay Steve Gaspoz Anthony Roger Francis Biner Daniel Hasmatuchi Vlad Constantin Decaix Jean Cachelin Christian Pierre Berthouzoz David Chiarelli Maxime Schmid Jérémy Pettinaroli Damien Rapillard Laurent Grand Pascal Pedroni François Luginbühl Flavio Pacot Olivier Clivaz Cédric Mabillard Eric Pignat Marc

Durée du projet: 01.01.2017 - 31.12.2020

Montant global du projet: 1'104'000 CHF

Statut: Completed

SOLUTION DE TRANSFERT D'ENERGIE PAR POMPAGE-TURBINAGE A PETITE ECHELLE

Role: Main Applicant

Financement: VS - Institut Systèmes industriels; OFEN; The Ark; VS - Institut Systèmes industriels

Description du projet : L'objectif du projet est de réaliser un premier prototype d'une puissance de 1 kW da ns le canal de fuite de la centrale de Lavey afin de valider les résultats des simulations et de pouvoir envisager une phase d'industrialisation du prod uit pour exploiter ce potentiel en Suisse. W de projet: 715-03 Cette industrialisation devra être fa ite par une entreprise vala isanne, raison pour laquelle l'entreprise Stahleinbau GmbH est intégrée dans le projet et réalisera déjà le premier prototype. De cette manière le transfert de connaissances entre la recherche et l'industrie est assuré. En fonct ion des résultats obtenus, une phase de commercialisation pourra être engagée à la suite du projet. Pour des raisons pratiques {toutes les mesures dans la phase recherche ont été faites sur le canal de fuite de Lavey), l'installation du prototype se fera sur la centrale de Lavey. Vers la fin du projet le prototype sera désinstallé à Lavey et disponible pour une autre centrale. La Fondat ion The Ark a déjà discuté avec les FMV pour une installation sur le canal de fuite de la centrale du Rhône à Chippis. De cette manière il sera possible d'accompagner la phase d'indus trialisation.

Research team within HES-SO: Chevailler Samuel , Vaccari Aldo , Münch-Alligné Cécile , Gaspoz Anthony Roger Francis , Biner Daniel , Hasmatuchi Vlad Constantin , Cachelin Christian Pierre , Schmid Jérémy , Rapillard Laurent , Barrade Philippe , Mabillard Eric

Partenaires académiques: Stahleinbau GmbH

Durée du projet: 01.11.2015 - 28.02.2018

Montant global du projet: 204'784 CHF

Statut: Completed

SCCER 4 WP 3.2 - Supply of Electricity - Contrat CTI 2013.0288

Role: Main Applicant

Financement: SIG - Services industriels de Genève

Description du projet : Actuellement, les projets de pompage-turbinage concernent principalement des aménagements à l'échelle nationale, voire internationale. Ces dernières années, des études ont par ailleurs été lancées sur des installations à caractère plus régional avec toutefois un positionnement économique sur un marché national, voire international. La présente proposition permet d'aborder l'échelon local. En effet, le projet proposé prévoit d'évaluer le potentiel technique et économique du pompage-turbinage de petite puissance (de l'ordre de 1MW) au niveau du réseau moyenne et basse tension en Suisse. L'objectif de ce projet est de répondre aux questions suivantes: ' Quel est le potentiel hydraulique Suisse pour l'installation d'un système de pompage-turbinage à petite échelle ? ' Quel modèle économique faut-il développer pour valoriser ce potentiel ? ' Quel type de technologie est approprié pour valoriser ce potentiel ? Les principaux résultats attendus sont : ' Développer et mettre à disposition un outil méthodologique d'analyse du potentiel technique et économique d'un site en Suisse basé sur des cas d'études. ' Valider le fonctionnement réversible d'une turbine Diagonale à double réglage.

Research team within HES-SO: Martignoni Shadya , Münch-Alligné Cécile , Decaix Jean , Grand Pascal

Partenaires académiques: VS - Institut Systèmes industriels; Mhylab

Durée du projet: 01.07.2015 - 30.06.2017

Montant global du projet: 150'000 CHF

Statut: Completed

Jean Decaix, Mathieu Mettille, Cécile Münch-Alligné

Role: Main Applicant

Financement: HES-SO Rectorat; VS - Institut Systèmes industriels; CTI; The Ark; VS - Institut Systèmes industriels

Description du projet : En 2012, la puissance mondiale installée dans le domaine de la petite hydraulique était estimée approximativement à 75 GW, représentant plus de 7% de la capacité hydraulique totale. Le potentiel mondial est estimé à 173 MW. En Suisse en 2010, il y avait déjà plus de 1300 petites centrales hydroélectriques en fonctionnement pour une capacité installée de 859 MW représentant plus de 5% de la production d'électricité du pays. La mise hors service progressive des centrales nucléaires en Suisse nécessite l'installation de nouveaux moyens de production d'électricité. Le potentiel de la petite hydraulique est évalué à 1,3-1,6 TWh selon l'OFEN. L'objectif de ce projet de développer une gamme de microturbines axiales pour récupérer l'énergie dissipée par les réducteurs de pression des réseaux d'eau potable Ce projet s'inscrit dans le cadre du projet SCCER 4 Supply of Electricity et du projet de recherche Hydro VS du programme The Ark Energy du canton du Valais.

Research team within HES-SO: Walpen Olivier , Chevailler Samuel , Vaccari Aldo , Martignoni Shadya , Münch-Alligné Cécile , Gaspoz Anthony Roger Francis , Biner Daniel , Hasmatuchi Vlad Constantin , Decaix Jean , Mudry Pierre-André , Cachelin Christian Pierre , Berthouzoz David , Evéquoz Blaise , Rapillard Laurent , Germanier Alain , Grand Pascal , Knupfer Pierre-André , Mabillard Eric , Pignat Marc

Partenaires professionnels: Fonds tiers 2015

Durée du projet: 01.11.2013 - 31.12.2016

Montant global du projet: 782'250 CHF

Statut: Completed

2024

Simulation of a Pelton turbine using the moving particle simulation method :

Scientific paper ArODES

application to two challenging situations

Journal of Hydraulic Research, 2024, 62, 4, 365-369

Summary:

Simulation of the flow in a Pelton turbine is a challenging task for mesh based methods due to the air/water mixture and the rotation of the runner. Meshless based methods are better suited for such flows and take advantage of the graphical power unit to speed up the calculation. Simulations of a Pelton turbine are carried out using the software Particleworks based on moving particle simulation, which is a meshless method. The efficiency drop due to the ‘falaise’ effect and the erosion of the splitter are computed and compared with either experimental measurements or the literature. The results show that this method is able to capture the tendency of the efficiency drop in agreement with the available data and at a lower computational cost than the mesh based methods. These encouraging results should motivate the community to test and validate such an approach.

Online loss calculation and optimization of a M3C driven externally excited SM

Scientific paper ArODES

Philippe Bontemps, Daniel Biner, Cécile Münch-Alligné, Drazen Dujic

IEEE Transactions on Industrial Electronics, 2024, 71, 6, 5608-5617

Summary:

Pumped hydro storage power plants are a truly renewable solution for large grid-connected energy storage. The evolution toward variable speed operation increases their flexibility and efficiency and ensures their relevance on a changing energy market. Exploiting all possible degrees of freedom in the machine operation as to maximize efficiency of the overall system allows to increase the profitability of the plant. Doing so in real-time on the same hardware-in-the-loop platform used for the validation of the control algorithm saves time and resources. The results presented here are collected from a real-time hardware-in-the-loop platform containing an industrial control platform. This article presents the most energy efficient steady-state and transient operation of an externally excited synchronous machine driven by a matrix modular multilevel converter for a PHSP application. To this end, this work presents a real-time compatible converter loss calculation applicable on the simplified implementation of the converter without the need to model the individual switches.

Projet TUNE - turbine for urban network

Professional paper ArODES

Khalid Essyad, Irene Samora, Vlad Hasmatuchi, Cécile Münch-Alligné, Amandine Massart

AQUA & GAS, 2024

Summary:

Le projet TUNE – Turbine for Urban Network – a étudié le concept de micro-turbinage dans des réseaux d’eau potable en milieu urbain, en configurations entre étages de pression. À la suite d’essais en laboratoire et des modélisations numériques, un démonstrateur a été installé dans le réseau de la ville de Pully. Le système, conçu pour maintenir la qualité de l’eau du réseau et pour être transparent pour le fontainier, est opérationnel depuis octobre 2023.

Computation fluid dynamics investigation of the flow in junctions :

Scientific paper ArODES

application to hydraulic short circuit operating mode

Jean Decaix, Mathieu Mertille, Jean-Louis Drommi, Nicolas Hugo, Cécile Münch-Alligné

LHB, 2023, 109, 1, 2290025

Summary:

Due to the penetration of stochastic low-carbon sources of production, requirements for flexible generation increase. The flexibility of pumped storage hydropower plants in pump mode can be improved by implementing hydraulic short circuit modes, which consists in operating the turbine(s) and the pump(s) in parallel. This new operating mode can be investigated by computational fluid dynamics to determine the head losses and to investigate the flow topology. Nine geometries of the Grand’Maison and Forces Motrices Hongrin-Léman (FMHL/FMHL+) plants are considered. Due to the lack of measurements, simulations are performed using different turbulence models and meshes to assess the uncertainty of the results. A statistical analysis of the results shows that low values of the head loss coefficients are obtained for geometries that limit the impingement of the flow on the walls and the development of a swirling flow downstream. Such geometries have the benefit of also limiting the wall pressure fluctuations and wall shear stresses, i.e. the risk of cavitation and the abrasion of the pipe walls due to sediment transport. These new results for the hydropower community are valuable for owners in implementing hydraulic short circuit mode in existing power plants or in designing new suitable junctions.

CFD investigation of the hydraulic short-circuit mode in the FMHL/FMHL+ pumped storage power plant

Scientific paper ArODES

Jean Decaix, Mathieu Mettille, nicolas Nugo, Bernard Valluy, Cécile Münch-Alligné

Energies, 2024, 17, 2, 473

Summary:

The flexibility of the FMHL+ pumped storage power plants can be improved by extending the hydraulic short-circuit operating mode. CFD simulations of the flow in three bifurcations are performed to calculate the head losses and to investigate the flow topology in the pipes. A specific attention is paid to the influence of the curvature correction that has been developed for two-equation RANS turbulence models. For the T-junction considered, the activation of the curvature correction influences the head losses whereas for the two Y-junctions computed, no effect is observed. By comparing with the Y-junctions, the T-junction leads to higher head losses and helicity in the pipes downstream of the bifurcation. Compared to the current the intragroup hydraulic short circuit operation permitted, the intergroup and interplant hydraulic short circuit mode should provide better performances with possible gains until of −55% in head losses and −94% in helicity upstream of the turbines.

2023

XFLEX hydro :

Book chapter ArODES

extending operation flexibility at EDF-hydro Grand Maison PSP

Jean-Louis Drommi, Benoit Joly, Denis Aelbrecht, Christophe Nicolet, Christian Landry, Cécile Münch-Alligné, Jean Decaix

Dans Boes, Robert, Droz, Patrice, Leroy, Raphaël, Role of dams and reservoirs in a successful energy transition (9 p.). 2023, Abingdon-on-Thames, UK : Taylor & Francis

Mathieu Mettille, Maxime Chiarelli, Jean Decaix, Samuel Rey-Mermet, Cécile Münch-Alligné

Summary:

Enhanced operation agility is now required from dispatchable generation means, hydro being top of the list. Increasing flexibility of legacy PSP has been implemented at Grand Maison scheme so as to provide regulating power in pump mode thanks to hydraulic short circuit technology. Extensive studies have been achieved to wave operational risk and provide operation boundaries. After 18 months, the demonstration has achieved 2500 hours of operation with full implementation onboard the EDF generating fleet.

Quels défis pour les turbines Pelton ? :

Professional paper ArODES

prédire leur comportement face à la demande accrue de flexibilité

bulletin.ch = Fachzeitschrift und Verbandsinformationen von Electrosuisse und VSE = Bulletin SEV/AES : revue spécialisée et informations des associations Electrosuisse et AES,

Jean Decaix, Cécile Münch-Alligné

Summary:

En Suisse, plus de 65 % des centrales haute chute sont équipées de turbines Pelton. Plusieurs projets de recherche en cours évaluent des méthodes de prédiction et de surveillance de leur comportement grâce aux simulations numériques ainsi qu’aux essais sur site et en laboratoire.

2022

Geometry, mesh and numerical scheme influencing the simulation of a Pelton jet with the OpenFOAM toolbox

Scientific paper ArODES

Energies, 15, 19, 7451

Summary:

Hydropower is a key source of electricity production for allowing the integration of intermittent renewable energy resources. Among the various hydraulic power plants around the world, the ones equipped with Pelton turbines already provide large flexibility that is still enhanced with the development, for instance, of the hydraulic short circuit operating mode. However, the knowledge of the flow inside Pelton turbines is still a challenging task, both numerically and experimentally, despite progress in the last two decades. One key feature of the Pelton efficiency is the jet quality, i.e., the jet velocity needs to be uniform, not perturbed by secondary flows and compact. The compactness of the jet is mainly dependent o nthe location of the jet detachment at the nozzle outlet, which is challenging for computational fluid dynamics simulations mainly due to numerical diffusion. Even if this point has already been mentioned in previous papers, the present paper focuses on all the parameters that can influence the jet detachment: the nozzle geometry, the mesh and the numerical scheme used to discretize the convective fluxes. The simulations of an existing Pelton injector are performed using the OpenFOAM toolbox. It is noticed that, in addition to the nozzle geometry and the mesh resolution at the nozzle outlet, the choice of the numerical schemes influences the jet detachment and, consequently, the jet diameter and discharge. The use of an anti-diffusive scheme such as the “SUPERBEE” limiter improves the prediction of the jet in accordance with the on-site measurements.

Dénoyer une galerie en charge pour améliorer la flexibilité d’une centrale hydroélectrique

Scientific paper ArODES

Jean Decaix, Anthony Gaspoz, Vlad Hasmatuchi, Matthieu Dreyer, Christophe Nicolet, Steve Crettenand, Cécile Münch-Alligné

LHB, 2022

Daniel Biner, Olivier Pacot, Jean Decaix, Cécile Münch-Alligné

Summary:

The development of new stochastic sources of renewable energy requires the availability of flexible energy sources also renewable to guarantee the stability of the electricity grid and the environmental commitments. As part of the “SmallFlex” pilot and demonstrator project, the increase in flexibility of a small run-of-river hydroelectric power station, equipped with two Pelton turbines, has been studied. The particularity of this high-head plant, with an installed capacity of 14 MW, is the absence of an upstream reservoir, which limits the control of the production to the prediction of the incoming flow. To increase the capacity of this plant, a storage volume including the grit chamber, the forebay tank and the upper part of the gallery has been identified. The present study focuses on the technical possibility of using this volume by performing analytical studies, scale model tests and on-site measurements. In addition, 1D digital simulations have identified the possibility to provide a primary control service to the grid by using this additional volume. Finally, the economic analysis shows the possibility of increasing the winter production and offering a primary control service thanks to this additional storage volume.

Plus de flexibilité grâce aux simulations :

Professional paper ArODES

évaluations du court-circuit hydraulique et de la vitesse variable

bulletin.ch = Fachzeitschrift und Verbandsinformationen von Electrosuisse und VSE = Bulletin SEV/AES : revue spécialisée et informations des associations Electrosuisse et AES, 2022, vol. 2, pp. 68-72

Summary:

Pour garantir la stabilité du futur réseau électrique, les centrales hydroélectriques devront être très flexibles. À l'aide de simulations numériques, le projet Xflex Hydro évalue le fonctionnement de centrales de pompage-turbinage en court-circuit hydraulique ainsi que l'utilisation des turbines à vitesse variable avant démonstration sur site.

2021

DuoTurbo :

Scientific paper ArODES

implementation of a counter-rotating hydroturbine for energy recovery in drinking water networks

Daniel Biner, Vlad Hasmatuchi, Laurent Rapillard, Samuel Chevailler, François Avellan, Cécile Münch-Alligné

Sustainability, 2021, vol. 13, no. 19, article no. 10717

Summary:

To enhance the sustainability of water supply systems, the development of new technologies for micro scale hydropower remains an active field of research. The present paper deals with the implementation of a new micro-hydroelectric system for drinking water facilities, targeting a gross capacity between 5 kW and 25 kW. A counter-rotating microturbine forms the core element of the energy recovery system. The modular in-line technology is supposed to require low capital expenditure, targeting profitability within 10 years. One stage of the DuoTurbo microturbine is composed of two axial counter-rotating runners, each one featured with a wet permanent magnet rim generator with independent speed regulation. This compact mechanical design facilitates the integration into existing drinking water installations. A first DuoTurbo product prototype is developed by means of a Computational Fluid Dynamics based hydraulic design along with laboratory tests to assess system efficiency and characteristics. The agreements between simulated and measured hydraulic characteristics with absolute errors widely below 5% validate the design approach to a large extent. The developed product prototype provides a maximum electrical power of 6.5 kW at a maximum hydraulic head of 75 m, reaching a hydroelectric peak efficiency of 59%. In 2019, a DuoTurbo pilot was commissioned at a drinking water facility to assess its long-term behavior and thus, to validate advanced technology readiness levels. To the best of the authors knowledge, it is the first implementation of a counter-rotating microturbine with independent runner speed regulation and wet rim generators in a real-world drinking water facility. A complete year of operation is monitored without showing significant drifts of efficiency and vibration. The demonstration of the system in operational environment at pre-commercial state is validated that can be attributed to a technology readiness level of 7. The overall results of this study are promising regarding further industrialization steps and potential broad-scale applicability of the DuoTurbo microturbine in the drinking water industry.

Augmenter la flexibilité de l’hydroélectricité :

Professional paper ArODES

diagnostic de la fatigue prématurée des turbines

Vlad Hasmatuchi, Jean Decaix, Maximilian Titzschkau, Cécile Münch-Alligné

Summary:

Dans le contexte récent d’exploitation des réseaux électriques, la nécessité d’augmenter la flexibilité des centrales hydroélectriques peut induire une fatigue prématurée sur certains composants. Une étude menée sur une turbine Francis de 100 MW a permis d’élaborer un protocole de diagnostic grâce à des mesures sur site et des simulations numériques.

Investigation of the time resolution set up used to compute the full load vortex rope in a Francis turbine

Scientific paper ArODES

Jean Decaix, Andreas Müller, Arthur Favrel, François Avellan, Cécile Münch-Alligné

Applied Sciences, 2021, vol. 11, no. 3, article no. 1168

Summary:

The flow in a Francis turbine at full load is characterised by the development of an axial vortex rope in the draft tube. The vortex rope often promotes cavitation if the turbine is operated at a sufficiently low Thoma number. Furthermore, the vortex rope can evolve from a stable to an unstable behaviour. For CFD, such a flow is a challenge since it requires solving an unsteady cavitating flow including rotor/stator interfaces. Usually, the numerical investigations focus on the cavitation model or the turbulence model. In the present works, attention is paid to the strategy used for the time integration. The vortex rope considered is an unstable cavitating one that develops downstream the runner. The vortex rope shows a periodic behaviour characterized by the development of the vortex rope followed by a strong collapse leading to the shedding of bubbles from the runner area. Three unsteady RANS simulations are performed using the ANSYS CFX 17.2 software. The turbulence and cavitation models are, respectively, the SST and Zwart models. Regarding the time integration, a second order backward scheme is used excepted for the transport equation for the liquid volume fraction, for which a first order backward scheme is used. The simulations differ by the time step and the number of internal loops per time step. One simulation is carried out with a time step equal to one degree of revolution per time step and five internal loops. A second simulation used the same time step but 15 internal loops. The third simulations used three internal loops and an adaptive time step computed based on a maximum CFL lower than 2. The results show an influence of the time integration strategy on the cavitation volume time history both in the runner and in the draft tube with a risk of divergence of the solution if a standard set up is used.

Production flexibility of small run-of-river power plants: KWGO smart-storage case study

Scientific paper

Münch-Alligné Cécile, Decaix Jean, Gaspoz Anthony Roger Francis, Hasmatuchi Vlad Constantin, Matthieu Dreyer, Christophe Nicolet, Alimirzazadeh Siamak, Jessica Zordan, Pedro Manso, Steve Crettenand

IOP Conference Series: Earth and Environmental Science, 2021 , vol. 774, no 1

Numerical simulations of Pelton turbine flow to predict large head variation influence

Scientific paper

Alimirzazadeh Siamak, Decaix Jean, François Avellan, Steve Crettenand, Münch-Alligné Cécile

IOP Conference Series: Earth and Environmental Science, 2021 , vol. 774, no 1

CFD simulations of a Y-junction for the implementation of hydraulic short-circuit operating mode

Scientific paper

Decaix Jean, Biner Daniel, Jean-Louis Drommi, François Avellan, Münch-Alligné Cécile

IOP Conference Series: Earth and Environmental Science, 2021 , vol. 774, no 1

Identification of 1-D cavitation model parameters by means of computational fluid dynamics

Scientific paper

Decaix Jean, Sébastien Alligné, Andrés Mueller, Christophe Nicolet, Münch-Alligné Cécile, François Avellan

Journal of Hydraulic Research, 2021 , pp. 1-12

Enhanced Operational Flexibility of a Small Run-of-River Hydropower Plant

Scientific paper

Decaix Jean, Gaspoz Anthony Roger Francis, Hasmatuchi Vlad Constantin, Matthieu Dreyer, Christophe Nicolet, Steve Crettenand, Münch-Alligné Cécile

Water, 2021 , vol. 13, no 14, pp. 1897-1897

2019

Hydro-structural stability investigation of a 100 MW Francis turbine based on experimental tests and numerical simulations

Scientific paper ArODES

Jean Decaix, Vlad Hasmatuchi, Maximilian Titzschkau, Laurent Rapillard, Cécile Münch-Alligné

IOP Conference Series: Earth and Environmental Science, 2019, vol. 405, article no. 012006

Summary:

This work focuses on a 100 MW Francis turbine prototype, part of one of the four horizontal ternary groups of Grimsel 2 PSPP, in Switzerland. Due to the massive integration of new renewable energy, the number of daily starts/stops of the machines has increased. Consequently, cracks on the runner blades of the Francis turbines have been noticed, without a clear explanation regarding the phenomenon responsible for their onset. To identify the main stress-full operating condition causing these cracks, the full turbine hill chart has been covered during the in situ measurement campaign including start-up, speed no-load, deep part load, best efficiency, full load and shut-down operating conditions. Then hydro-structural stability diagnosis diagrams of the prototype have been established for the whole operating range of the turbine. In addition, CFD numerical simulations for different operating conditions, along with FEM structural and modal analysis of the runner, have been carried out. The onboard measurements evidenced the highest mechanical stresses on the runner blades at speed no-load operating condition. This conclusion is supported by CFD and FEM analysis, which put in evidence the possible excitation of one of the runner's eigen frequency by the fluctuations of the pressure field.

Numerical investigation of solutions to suppress the inlet vortex of an existing booster pump

Scientific paper ArODES

Jean Decaix, Anthony Gaspoz, D. Fischer, Cécile Münch-Alligné

IOP Conference Series: Earth and Environmental Science, 2019, vol. 405, article no. 012036

Summary:

The study focuses on a booster pump used to feed the main pump of one unit of the FMHL hydropower plant (Veytaux I). From the beginning of the operation of the power plant, vibrations have been observed on this booster pump with sometimes the presence of cavitation erosion. The visualisations carried out show that a cavitating vortex develops at the suction side of the booster pump runner and causes the measured vibrations. The booster pump is running without any modification since the beginning of the operation of the power plant, however future mechanical failures cannot be excluded, since in these harsh conditions, the permissible mechanical strain shall be exceeded. Flow numerical investigations have been carried out using OpenFOAM and shown the presence of vortices below the bell of the booster pump. The main vortex observed is assumed to be responsible for the vibrations due to its interaction with the runner blades and to promote the inception of cavitation, which could explain the cavitation erosion observed. Several modifications of the chamber have been considered by simulation. Two of them provide a solution to suppress or at least to damp the vibrations due to the presence of vortices in the bell inlet.

On-board measurements at a 100 MW high-head Francis turbine

Scientific paper ArODES

Maximilian Ttizschkau, Vlad Hasmatuchi, Jean Decaix, Cécile Münch-Alligné

Wasserwirtschaft, 2019, no. 1

Pacot Olivier, Decaix Jean, Münch-Alligné Cécile, Pettinaroli Damien

Summary:

Modern sources of energy, like solar and wind, force hydropower machines to change their operational behaviour. Rapid changes in the availability of renewable energies lead to instabilities in the grid, which need to be stabilized by flexible machine operation (Lowys et al. [1]). This leads to a significant change in hydropower operations, e.g. to an increasing number of start-stop events (Seidel et al. [2], Robert et al. [3], Coutu and Chamberland-Lauzon [4]). The four ternary machine groups at the Grimsel 2 power plant have been designed under completely different circumstances in the late 1970's and are suffering from this change in operation. After only 35'000 hrs of operation all runners show fatigue cracks at the trailing edges close to the hub which needed to be repaired effortful. As a part of these repairs, the chamfer between the blade and the hub was increased from about 5 mm to 12 mm with local welding and heat treatment to reduce stresses. Apparently, this seems to work out fine but, since the source of the damage was not detected, this situation was not satisfying for the plant owner. The turbines were running at smooth conditions most of the time. Since deep part load could be eliminated as a source of those cracks, it was assumed that either start-up, shutdown or some unknown phenomena lead to the cracks. From recent literature (Gagnon et al. [5] & [6]), it is assumed that the start-up process can be responsible for the observed kind of cracks. To get more information, extensive measurements have been performed on the Group 2 of the power plant. The overall goal of this research is to advice the plant owner concerning the operation of the machines to increase the lifetime of the existing runners.

Cost-effective CFD simulation to predict the performance of a hydrokinetic turbine farm

Scientific paper

IOP Conference Series: Earth and Environmental Science, 2019 , vol. 405

Summary:

After the performance assessment of a new hydrokinetic turbine prototype in the tailrace channel of a run-of-river power plant (Lavey, CH), the possibility to install a farm of such hydrokinetic turbines on this pilot site is investigated. In order to identify the optimal number and size of the machines as well as their location on this site, numerical simulations are carried out. Such a process requires to simulate a set of several free surface flow computations including different configurations of the farm in order to maximize the energy tapped by the machines. However, free surface flow computations are time and resources consuming. To allow such flow investigations, a different approach has been selected. In the present study, the turbines were replaced by a model mimicking the resistance effect of the machines. This model consists in a pressure drop applied at the turbine location to emulate the disturbance effect on the flow, especially the wake effect that will modify the available kinetic energy for the neighboring machines. Finally, it results that such a low CPU approach allows us to estimate the best location of the hydrokinetic turbines maximizing the energy harvested.

2018

CFD Investigation of a high head Francis turbine at speed no-load using advanced URANS models

Scientific paper ArODES

Jean Decaix, Vlad Hasmatuchi, Maximilian Titzschkau, Cécile Münch-Alligné

Applied Sciences, 2018, vol. 8, no. 12, article no 2505

Summary:

Due to the integration of new renewable energies, the electrical grid undergoes instabilities. Hydroelectric power plants are key players for grid control thanks to pumped storage power plants. However, this objective requires extending the operating range of the machines and increasing the number of start-up, stand-by, and shut-down procedures, which reduces the lifespan of the machines. CFD based on standard URANS turbulence modeling is currently able to predict accurately the performances of the hydraulic turbines for operating points close to the Best Efficiency Point (BEP). However, far from the BEP, the standard URANS approach is less efficient to capture the dynamics of 3D flows. The current study focuses on a hydraulic turbine, which has been investigated at the BEP and at the Speed-No-Load (SNL) operating conditions. Several “advanced” URANS models such as the Scale-Adaptive Simulation (SAS) SST k − ω and the BSL- EARSM have been considered and compared with the SST k − ω model. The main conclusion of this study is that, at the SNL operating condition, the prediction of the topology and the dynamics of the flow on the suction side of the runner blade channels close to the trailing edge are influenced by the turbulence model.

Hydraulic performance evaluation of a micro-turbine with counter rotating runners by experimental investigation and numerical simulation

Scientific paper ArODES

Elena Vagnoni, Loïc Andolfatto, Sylvain Richard, Cécile Münch-Alligné, François Avellan

Renewable Energy, 2018, 126, pp. 943-953

Summary:

The development of energy recovery systems on existing water utility networks is a new challenge for increasing the sustainability of electricity generation mix. The concept of the new micro-turbine with counter rotating runners braces this goal by allowing the recovery of the energy which is spoiled in pressure reducing valves in many water supply networks. The hydraulic performances of the micro-turbine are evaluated through an analysis on the angular momentum balance applied to the investigated cross-sections of the machine. For this analysis, an experimental campaign involving 2D Laser Doppler Velocimetry (LDV) is performed to measure the velocity field of the flow at the inlet and outlet sections of the machine. Since the optical access to perform LDV measurements is blocked close to the hub of the runners, a further analysis on the mass balance and numerical simulations are performed to complete the velocity profiles and to evaluate the machine performance. The combination of numerical and experimental methods grants a full study on the operating condition of the micro-turbine and strengthens the results achieved. The results back up the best operating condition of the machine for different discharges and support further improvements of the runner blades shape.

A dynamic approach for faster performance measurements on hydraulic turbomachinery model testing

Scientific paper ArODES

Vlad Hasmatuchi, Alin Ilie Bosioc, Sébastien Luisier, Cécile Münch-Alligné

Applied Sciences, 2018, vol. 8, no. 9, article no 1426

Summary:

During the design and optimization of hydraulic turbomachines, the experimental evaluation of hydraulic performances beyond the best efficiency point and for off-design conditions remains essential to validate the simulation process and to finalize the development. In this context, an alternative faster method to measure the efficiency of hydraulic turbomachines using a dynamic approach has been investigated. The so-called “sliding-gate” dynamic measurement method has been adapted and implemented on the hydraulic test rig of the HES-SO Valais//Wallis, Sion, Switzerland. This alternative approach, particularly gainful for small-hydro for which the investment devoted to development is limited, has been successfully assessed on two cases for drinking water networks energy recovery. A 2.65 kW double-regulated laboratory prototype of a tubular axial micro-turbine with two independent variable speed counter-rotating runners and a 11 kW multi-stage centrifugal pump-as-turbine (PAT) with variable speed have been selected. The hydraulic efficiency results obtained by dynamic measurements are compared to the ones obtained by the classical steady point-by-point method. This dynamic method, suitable not only for hydraulic machinery, allows: (i) reducing significantly (up to 10×) the time necessary to draw the complete efficiency characteristics of a hydraulic machine; (ii) rapidly detecting the hydrodynamic instabilities within the operating range of the machine.

Experimental assessment of a new kinetic turbine performance for artificial channels

Scientific paper ArODES

Cécile Münch-Alligné, Jérémy Schmid, Sylvain Richard, Anthony Gaspoz, Nino Brunner, Vlad Hasmatuchi

Water, 2018, 10, 3, 311

Summary:

An experimental investigation to measure the performance of a first prototype of a kinetic turbine is presented. This turbine, developed using numerical simulation, recovers the kinetic energy of water in free surface canals. To assess the performance of the machine, a first prototype as well as an open-air platform were built, both installed in the tailrace canal of Lavey hydropower plant. This is the first time in Switzerland that on-site experiments have been carried out for kinetic turbines. An experimental procedure was set up using measurements in the laboratory and on site to assess the power coefficient of the turbine as a function of the tip speed ratio. The influence of the turbine depth and the tilt of the turbine axis were also explored. A maximal power coefficient of 0.93 was reached for the higher tilt and depth investigated.

Un stockage local et compétitif de l’énergie :

Scientific paper ArODES

le pompage-turbinage à petite échelle recèle de nombreux avantages

Shadya Martignoni, Laurent Smati, Vincent Denis, Cécile Münch-Alligné

Haute école d’ingénierie et de gestion du canton de Vaud (HEIG-VD) HES-SO // Haute Ecole Spécialisée de Suisse Occidentale, 2018, 2, pp. 27-31

Summary:

Grâce à sa capacité de stockage, une station de transfert d’énergie par pompage-turbinage à petite échelle est à même de contribuer à l’intégration des énergies renouvelables intermittentes et de procurer à un prix compétitif les services système que ne fournissent pas ces nouveaux moyens de production

2017

URANS models for the simulation of full load pressure surge in Francis turbines validated by particle image velocimetry

Scientific paper ArODES

Jean Decaix, A. Müller, A. Favrel, François Avellan, Cécile Münch-Alligné

Journal of Fluids Engineering, 2017, vol. 139, no. 12, article no. 121103

Summary:

Due to the penetration of alternative renewable energies, the stabilization of the electrical power network relies on the off-design operation of turbines and pump-turbines in hydro-power plants. The occurrence of cavitation is however a common phenomenon at such operating conditions, often leading to critical flow instabilities which undercut the grid stabilizing capacity of the power plant. In order to predict and extend the stable operating range of hydraulic machines, a better understanding of the cavitating flows and mainly of the transition between stable and unstable flow regimes is required. In the case of Francis turbines operating at full load, an axisymmetric cavitation vortex rope develops at the runner outlet. The cavity may enter self-oscillation, with violent periodic pressure pulsations. The flow fluctuations lead to dangerous electrical power swings and mechanical vibrations, dictating an inconvenient and costly restriction of the operating range. The present paper reports an extensive numerical and experimental investigation on a reduced scale model of a Francis turbine at full load. For a given operating point, three pressure levels in the draft tube are considered, two of them featuring a stable flow configuration and one of them displaying a self-excited oscillation of the cavitation vortex rope. The velocity field is measured by two-dimensional (2D) particle image velocimetry (PIV) and systematically compared to the results of a simulation based on a homogeneous unsteady Reynolds-averaged Navier–Stokes (URANS) model. The validation of the numerical approach enables a first comprehensive analysis of the flow transition as well as an attempt to explain the onset mechanism.

RANS computations for identification of 1-D cavitation model parameters :

Scientific paper ArODES

application to full load cavitation vortex rope

S. Alligné, Jean Decaix, A. Müller, C. Nicolet, François Avellan, Cécile Münch-Alligné

Journal of Physics: Conference Series, 2017, vol. 813, article no. 012032

Summary:

2016

Experimental characterization of a five blade tubular propeller turbine for pipe inline installation

Scientific paper ArODES

Irene Samora, Vlad Hasmatuchi, Cécile Münch-Alligné, Mário J. Franca, Anton J. Schleiss, Helena M. Ramos

Renewable Energy, 2016, vol. 95, pp. 356-366

Summary:

The interest in micro-hydropower in existing infrastructure is increasing since this is a technology with low environmental impacts and potential for energy recovery in different types of installation. The technologies available for these schemes are still restricted and it is a current subject for research. In this work an experimental characterization of an inline tubular propeller suitable for pressurized systems, such as water supply and distribution networks, is presented. In the framework of the European Project HYLOW, started in 2008, a first prototype has been developed using CFD analysis and tested. Nevertheless, optimization and validation were still necessary. An improved model has been now adequately tested in the laboratory and proves to be interesting in terms of potential application. The experimental investigation evidenced that the new turbine has efficiencies of around 60% for low-headed operations, below 50 m.

RANS computations for identification of 1-D cavitation model parameters :

Scientific paper ArODES

application to full load cavitation vortex rope

Sébastien Alligné, Jean Decaix, Andrei Müller, Christophe Nicolet, François Avellan, Cécile Münch-Alligné

IOP Conference Series: Earth and Environmental Science, 2016, vol. 49, article no. 082014

Summary:

Due to the massive penetration of alternative renewable energies, hydropower is a key energy conversion technology for stabilizing the electrical power network by using hydraulic machines at off design operating conditions. At full load, the axisymmetric cavitation vortex rope developing in Francis turbines acts as an internal source of energy, leading to an instability commonly referred to as selfexcited surge. 1-D models are developed to predict this phenomenon and to define the range of safe operating points for a hydropower plant. These models involve several parameters that have to be calibrated using experimental and numerical data. The present work aims to identify these parameters with URANS computations with a particular focus on the fluid damping rising when the cavitation volume oscillates. Two test cases have been investigated: a cavitation flow in a Venturi geometry without inlet swirl and a reduced scale model of a Francis turbine operating at full load conditions. The cavitation volume oscillation is forced by imposing an unsteady outlet pressure conditions. By varying the frequency of the outlet pressure, the resonance frequency is determined. Then, the pressure amplitude and the resonance frequency are used as two objectives functions for the optimization process aiming to derive the 1-D model parameters.

Head loss coefficient through sharp-edged orifices

Scientific paper ArODES

Nicolas J. Adam, Giovanni De Cesare, Anton J. Schleiss, Sylvain Richard, Cécile Münch-Alligné

IOP Conference Series: Earth and Environmental Science, 2016, vol. 49, article no. 062009

Summary:

Nowadays, high-head power plants could increase their installed power capacity for many reasons, e.g. dam heightening, increase of their peak power capacity or refurbishment with new turbines. Frequently, due to several considerations, e.g. topographical or economical limitations, the existing surge tank cannot be extended to keep previous safety levels and efficiency. A valuable way to adapt these surge tanks is to place a throttle at their entrance like, for example, an orifice. The main effect of this adaptation is the introduction of head losses that reduce the extreme levels in the surge tank due to the mass oscillations resulting from a closure or opening of downstream discharge control. This research studies the influence of the edge angle of a ASME-standard orifice on the head losses. This angle introduces an asymmetrical behavior and influences head losses. Different angles are tested from 0° to the 67° (biggest angle possible for this configuration). The first step of this study is to determine experimentally the steady losses produced by orifice for several discharges. In the second step, a numerical model on ANSYS CFX is performed. Combining the two approaches, it is possible to understand and quantify the effect of the edge angle.

Energy production with a tubular propeller turbine

Scientific paper ArODES

Irene Samora, Vlad Hasmatuchi, Cécile Münch-Alligné, Mario J. Franca, Anton J. Schleiss, Helena M. Ramos

IOP Conference Series: Earth and Environmental Science, 2016, vol. 49, article no. 102001

Summary:

Micro-hydropower is a way of improving the energetic efficiency of existent water systems. In the particular case of drinking water systems, several studies have showed that pressure reducing valves can be by-passed with turbines in order to recover the dissipated hydraulic energy to produce electricity. As conventional turbines are not always cost-effective for power under 20 kW, a new energy converter is studied. A five blade tubular propeller (5BTP), assessed through laboratorial tests on a reduced model with a diameter of 85 mm diameter and a maximal output power of 300 W, is addressed in this work. Having showed promising potential for further development, since global efficiencies of around 60% were observed, the turbine has been further used to estimate the potential for energy production in a real case study. A sub-grid of the drinking water system of the city of Lausanne, Switzerland, has been used to obtain an annual energy production through hourly simulations with several turbines.

Engineering & performance of DuoTurbo :

Scientific paper ArODES

microturbine with counter-rotating runners

Daniel Biner, Vlad Hasmatuchi, S. Richard, Samuel Chevailler, Loïc Andolfatto, François Avellan, Cécile Münch-Alligné

IOP Conference Series: Earth and Environmental Science, 2016, vol. 49, article no. 102013

Summary:

Considering the nuclear phase-out strategy of several European countries and the future tendency to promote renewable energies, the exploitation of small hydropower sites (<10 MW) becomes increasingly important. In this framework DuoTurbo Turbine, a new DuoTurbo-microturbine prototype for drinking water networks has been jointly developed by the HES-SO Valais//Wallis, the EPFL-Laboratory for Hydraulic Machines and industrial partners. The modular in-line "plug & play" technology requires low investment, reaching economic feasibility with an available power between 5 kW and 25 kW. One stage of the microturbine consists of two axial counter-rotating runners that form a compact independent unit. Each runner of the turbine holds its own rim generator, the DuoTurbo-configuration involving that each hydraulic runner is integral with each electrical rotor. The possibility of stacking several stages in series enables covering quite a wide range of hydraulic power and, thus, recovering a maximum of energy dissipated in release valves of water supply systems. The present work introduces the global concept of the implemented prototype of the DuoTurbo-microturbine, to target a maximal injected power of 5 kW for a discharge of 9 l/s and a head of 24.5 m per stage. The main features of the hydraulic, the mechanical, the electrical and the electronic design are presented. The hydraulic performance is, then, assessed using CFD simulations for the expected operating range. Finally, the performance measurements of the single-stage prototype installed in the hydraulic test rig of the HES-SO Valais//Wallis are presented.

Simulation of energy recovery on water utility networks by a micro-turbine with counter-rotating runners

Scientific paper ArODES

Loïc Andolfatto, Elena Vagnoni, Vlad Hasmatuchi, Cécile Münch-Alligné, François Avellan

IOP Conference Series: Earth and Environmental Science, 2016, vol. 49, article no. 102012

Summary:

Wherever relief valves and other energy dissipation devices are installed to limit the pressure, water utility networks provide unexploited hydropower potentials. This is mainly due to a lack of economically viable technologies for energy recovery in the pico and micro hydropower range below 100 kW. Micro-turbine with counter-rotating runners proved suitable to harvest these potentials with limited investments and almost no environmental impact. An appropriate command strategy must therefore be applied to maximize the recovered energy. This paper deals with the construction of a Virtual Energy Recovery Station (VERS) model to simulate the energy recovery on a given installation site. It includes models of the turbine, of the water consumption and it allows to implement various command strategies. The VERS can serve various purposes. The fine tuning of the command algorithm for a specific installation site is demonstrated in the paper.

On the dynamic measurements of hydraulic characteristics

Scientific paper ArODES

Vlad Hasmatuchi, Alin Bosioc, Cécile Münch-Alligné

IOP Conference Series: Earth and Environmental Science, 2016, vol. 49, article no. 062001

Summary:

The present work introduces the implementation and validation of a faster method to measure experimentally the efficiency characteristics of hydraulic turbomachines at a model scale on a test rig. The case study is represented by a laboratory prototype of an in-line axial microturbine for water supply networks. The 2.65 kW one-stage variable speed turbine, composed by one upstream 5-blade runner followed by one counter-rotating downstream 7-blade runner, has been installed on the HES-SO Valais/Wallis universal test rig dedicated to assess performances of small hydraulic machinery following the IEC standard recommendations. In addition to the existing acquisition/control system of the test rig used to measure the 3D hill-chart of a turbine by classical static point-by-point method, a second digitizer has been added to acquire synchronized dynamic signals of the employed sensors. The optimal acceleration/deceleration ramps of the electrical drives have been previously identified in order to cope with the purpose of a reduced measurement time while avoiding errors and hysteresis on the acquired hydraulic characteristics. Finally, the comparison between the turbine efficiency hill-charts obtained by dynamic and static point-by-point methods shows a very good agreement in terms of precision and repeatability. Moreover, the applied dynamic method reduces significantly (by a factor of up to ten) the time necessary to measure the efficiency characteristics on model testing.

Computational fluid dynamics as a tool to predict the air pollution dispersion in a neighborhood :

Scientific paper ArODES

a research project to improve the quality of life in cities

Gilles Triscone, Nabil Abdennadher, Christophe Balistreri, Olivier Donzé, D. Greco, Patrick Haas, H. Haas-Pekoz, T. Mohamed-Nour, Pierre Munier, Piero Pontelandolfo, Roberto Putzu, Jacques Richard, H. Sthioul, Nicolas Delley, D. Choffat, Elena-Lavinia Niederhäuser, Roger Schaer, Henning Müller, Jean Decaix, Sylvain Richard, Cécile Münch-Alligné, P. Kunz, F. Despot

International Journal of Sustainable Development and Planning, 2016, vol. 11, no. 4, pp. 546-557

Summary:

In large cities, pollution composed of many different chemical components and small particles is an important public health problem that affects especially children and people presenting breathing difficulties. One challenge for public authorities is to respect the norms given by the central state, but how? Today, concrete methods for reducing pollution are perceived by the majority of citizens as constraints. However, the authorities have the possibility of modifying the wind’s action by imposing architectural constraints, such as building emplacement and roof structure. This is the main objective of the Geneva ‘Clean City’ project financed by the University of Applied Sciences Western Switzerland. ‘Clean City’ focuses its research on one of Geneva’s polluted neighborhood called Pâquis, which is situated directly on the Geneva lake front. The project attempts to understand the dispersion of pollution from an experimental and a numerical point of view. After validation of the technique for a simple case, we compare environmental measurements on a 1/500 3D scale model of the Pâquis installed in an instrumented wind tunnel with Computational Fluid Dynamics (CFD) simulation obtained with the help of cloud computing.

2015

RANS computations of tip vortex cavitation

Scientific paper ArODES

Jean Decaix, Guillaume Balarac, Matthieu Dreyer, Mohamed Farhat, Cécile Münch-Alligné

Journal of Physics: Conference Series, 2015, vol. 656, article no. 012183

Summary:

The present study is related to the development of the tip vortex cavitation in Kaplan turbines. The investigation is carried out on a simplified test case consisting of a NACA0009 blade with a gap between the blade tip and the side wall. Computations with and without cavitation are performed using a R ANS modelling and a transport equation for the liquid volume fraction. Compared with experimental data, the R ANS computations turn out to be able to capture accurately the development of the tip vortex. The simulations have also highlighted the influence of cavitation on the tip vortex trajectory.

Rans computations of a cavitating tip vortex

Book chapter ArODES

Jean Decaix, Guillaume Balarac, Cécile Münch-Alligné

Dans Caignaert, Guy, Cunge, Jean A., Gourbesville, Philippe, Advances in Hydroinformatics (pp. 519-529). 2015, Singapore : Springer

Summary:

The Swiss national research project Hydronet 2 gathers a consortium of industrial and academic partners supported by the Competence Center of Energy and Mobility (CCEM) and Swiss Electric Research (SER) in order to improve the hydropower plants. One of the research topic focuses on the cavitating tip vortex. Such a vortex takes place in axial turbines as Kaplan turbines used for producing hydroelectricity. This phenomenon drives a lot of drawbacks such as erosion, unsteady flow rate and a decrease of the turbine efficiency. To better understand the behaviour of the tip vortex, computations of a simple test case are performed. The test case consists in a NACA profile mounted in a channel with a gap between the NACA tip and the lateral wall. The computations are carried out with the OpenFOAM solver both in one-phase and two-phase flows. The turbulent motion is modelled with a RANS approach. For the two-phase flow computations, the phase change between liquid and vapour is achieved with the model proposed by Kunz. The results will be compared in cavitating and non-cavitating cases with the experimental data provided by the EPFL Laboratory for Hydraulic Machines. The comparisons deal with global picture of the flow, the trajectory of the tip vortex and the velocity field downstream the NACA profile.

Design and control of a new hydraulic test rig for small hydro turbines

Scientific paper ArODES

Vlad Hasmatuchi, Francisco Botero, Shadya Gabathuler, Cécile Münch-Alligné

The International Journal on Hydropower Dams, 2015, vol. 22, no. 4, pp. 51-60

Summary:

The University of Applied Sciences and Arts Western Switzerland - Sion (HES-SO Valais/Wallis) has installed in its hydraulic laboratory a new universal test rig to assess hydraulic performances of different types of small-power axial and radical-axial turbines and/or pumps (up to 10kW), valves as well as other components of hydraulic systems. The IEC 60193 standard recommendations are implemented. The closed-loop hydraulic circuit is fed by three recirculating multistage centrifugal pumps (with variable speed), connected in parallel, that can deliver a maximum discharge of 45 m3/h and a maximum pressure of 160 mWC. The pressurized reservoir installed downstream the test section allows simulating different implantation levels of the model and therefore recovering the cavitation performances as well. The operation of the test rig is controlled with an automatic system through a customized Labview® interface that allows for real-time measurement and dispaly instantaneous values of pumps speed, flow discharge, testing head, water temperature and Thoma number. The main contribution of this paper is to introduce a state-of-the-art approach of an autoamtic regulation for test rigs. The full capabilities of a National Instruments cRIO-9074 are used to develop an autonomous regulation system based on real time measurements in order to keep constant the value of the desired parameters. In addition, a special care is put on the wireless communication architecture between the hydraulic test rig and further measurement/monitoring systems (e.g. testing model control system). Meanwhile, the test rig control system manages a dedicated cloud of variables and makes them available for client systems. Finally, such approach allows for safe data centralization, storage and sharing on model testing.

2014

Mind the gap :

Scientific paper ArODES

a new insight into the tip leakage vortex using stereo-PIV

Matthieu Dreyer, Jean Decaix, Cécile Münch-Alligné, Mohamed Farhat

Experiments in Fluids, 2014, vol. 55, article no. 1849

Summary:

The tip leakage vortex (TLV), which develops in the clearance between the rotor and the stator of axial hydro turbines, has been studied for decades. Yet, many associated phenomena are still not understood. For instance, it remains unclear how the clearance size is related to the occurrence of cavitation in the vortex, which can lead to severe erosion. Experiments are here carried out on the influence of the clearance size on the tip vortex structure in a simplified case study. A NACA0009 hydrofoil is used as a generic blade in a water tunnel while the clearance between the blade tip and the wall is varied. The 3D velocity fields are measured using Stereo Particle Image Velocimetry (SPIV) in three planes located downstream of the hydrofoil for different values of the upstream velocity, the incidence angle and a large number of tip clearances. The influence of the flow conditions on the structure of the TLV is described through changes in the vortex intensity, core axial flow, vortex center position and wandering motion amplitude. Moreover, high-speed visualizations are used to highlight the vortex core trajectory and clearance flow alteration, turning into a wall jet as the tip clearance is reduced. The measurements clearly reveal the existence of a specific tip clearance for which the vortex strength is maximum and most prone to generating cavitation.

RANS and LES computations of the tip-leakage vortex for different gap widths

Scientific paper ArODES

Jean Decaix, Guillaume Balarac, Matthieu Dreyer, Mohamed Farhat, Cécile Münch-Alligné

Journal of Turbulence, 2015, vol. 16, no. 4, pp. 309-341

Summary:

In hydraulic turbines, the tip-leakage vortex is responsible for flow instabilities and for promoting erosion due to cavitation. To better understand the tip vortex flow, Reynolds-averaged Navier–Stokes (RANS) and large eddy simulation (LES) computations are carried out to simulate the flow around a NACA0009 blade including the gap between the tip and the wall. The main focus of the study is to understand the influence of the gap width on the development of the tip vortex, as for instance its trajectory. The RANS computations are performed using the open source solver OpenFOAM 2.1.0, two incidences and five gaps are considered. The LESs are achieved using the YALES2 solver for one incidence and two gaps. The validation of the results is performed by comparisons with experimental data available downstream the trailing edge. The position of the vortex core, the mean velocity and the mean axial vorticity fields are compared at three different downstream locations. The results show that the mean behaviour of the tip vortex is well captured by the RANS and LES computations compared to the experiment. The LES results are also analysed to bring out the influence of the gap width on the development of the tip-leakage vortex. Finally, a law that matches the vortex trajectory from the leading edge to the mid-chord is proposed. Such a law can be helpful to determine, in case of cavitation, if the tip vortex will interact with the walls and cause erosion.

2013

Numerical simulations of a counter-rotating micro-turbine

Book chapter ArODES

Cécile Münch-Alligné, Sylvain Richard, Bastien Meier, Vlad Hasmatuchi, François Avellan

Dans Caignaert, Guy, Cunge, Jean, Gourbesville, Philippe, Advances in hydroinformatics (pp. 363-373). 2013, Singapore : Springer

Summary:

A counter-rotating hydraulic micro-turbine has been developed to recover the energy lost in release valves of water supply network. This compact two-stage axial turbine could be installed in line with the conduit, reducing the infrastructure investments, which is a crucial point for small power plant. The two stages of the turbine allow to use this axial turbine in case of high head conditions. Steady numerical simulations of the flow in the turbine have been carried out using ANSYS CFX to develop the design of the turbine and assess its performance. The influence of numerical set up such as the mesh size and the type of interface between the stator and the two rotating parts has been studied. The influence of the elbow and the honeycomb on the inflow conditions was also assessed. A best efficiency of 85 % is reached when the two runners counter-rotate at the same nominal speed. When the turbine operates under part and full load conditions, the relative rotational speed between the two runners will allow optimizing the efficiency.

Design optimization of a 2D blade by means of milling tool path

Scientific paper ArODES

Christian Vessaz, Christophe Tournier, Cécile Münch-Alligné, François Avellan

CIRP Journal of Manufacturing Science and Technology, 2013, vol. 6, no. 3, pp. 157-166

Summary:

In a conventional design and manufacturing process, turbine blades are modeled based on reverse engineering or on parametric modeling with Computer Fluids Dynamics (CFD) optimization. Then, only raises the question of the manufacturing of the blades. As the design does not take into account machining constraints and especially tool path computation issues in flank milling, the actual performance of the machined blade could not be optimal. In this paper, a new approach is used for the design and manufacture of turbine blades in order to ensure that the simulated machined surface produces the expected hydraulic properties. This consists in the modeling of a continuous tool path based on numerical simulation rather than the blade surface itself. Consequently, this paper aims at defining the steps of the proposed design approach including geometrical modeling, mesh generation, CFD simulation and genetic optimization. The method is applied on an isolated blade profile in a uniform water flow and results are compared to the conventional design process.

Exploitation du potentiel de la petite hydraulique :

Professional paper ArODES

situation actuelle et exemple de développement

Cécile Münch-Alligné, François Avellan

Summary:

La mise hors service progressive des centrales nucléaires en Suisse nécessite l’installation de nouveaux moyens de production d’électricité. Dans ce contexte, un projet de recherche visant au développement de nouvelles technologies pour la petite hydraulique a été mis en place par la HES-SO Valais et l’EPFL. Une nouvelle microturbine axiale destinée à récupérer l’énergie hydraulique dissipée par les réducteurs de pression des circuits de distribution d’eau potable est notamment en cours de développement.

2023

Characterisation of dominant frequencies during transient operations of Pelton turbines at the FMHL PSP

Conference ArODES

Maxime Chiarelli, Cécile Münch-Alligné, David F. Vetsch, Robert M. Boes

Proceedings of HYDRo 2023, 16-18 October 2023, Edinburgh, Scotland

Münch-Alligné Cécile, Rey-Mermet Samuel

Summary:

The rise of renewable energies like solar and wind has transformed hydroelectric storage power plant operations, leading to more frequent starts and stops and accelerated wear on machine components. Previous studies have shown the potential to detect runner natural frequencies using sensors placed on the bearing of horizontal Pelton turbines. The present study explores the non-intrusive measurement of these frequencies during transient operations. Two vibration fingerprints and a transmissibility experiment were conducted during a runner replacement on a ternary unit at the Forces Motrices Hongrin Léman (FMHL) pumped storage power plant (PSP) in Switzerland. The ternary unit features two Pelton turbines mounted side by side on the same shaft. During the refurbishment of the unit, both runners were replaced at the same time. The vibration measurements aimed at understanding how the runners affected the power unit's dynamic behaviour and assess the feasibility of capturing the runners' natural frequencies from remote measurement positions. The transmissibility experiment conducted before replacing the runners reveals differences in the axial natural frequencies of the two original runners, ranging from 6 to 9 Hz (1.3% to 1.7%). Additionally, the experiment indicates an average attenuation of two orders of magnitude of the vibration level from the runners to the bearings. During startup transients measured with the original runners, frequencies which coincide with tangential and tangential in counter-phase mode of the runners are excited. In contrast, when analysing startup transients with the new runners, the results indicated that maximum amplitudes were concentrated within a higher frequency range, corresponding to the tangential and axial in counter phase natural frequencies of the new runner. The results are consistent with prior studies and suggest the potential for advanced non-intrusive vibration monitoring tools to improve Pelton turbine reliability and safety.

2022

Flexibilité et durabilité des aménagements hydroélectriques

Conference

en collaboration avec Prof. Cécile Münch-Alligné

Journée de l'Energie CREM à la Foire du Valais 2022, 05.10.2022 - 21.10.2022, Martigny

Discretization uncertainties of flow and fatigue damage simulations of a reversible Francis pump-turbine at off-design operation in turbine mode

Conference ArODES

Daniel Biner, Philippe Bontemps, Drazen Dujic, Cécile Münch-Alligné

Springer Water ; Proceedings of the SimHydro 2021,16-18 June 2021, Sophia Antipolis, France

Summary:

In the framework of the XFLEX HYDRO H2020 European Project, a 5 MW reversible Francis pump-turbine prototype, equipped with an industrial full size frequency converter, is investigated to demonstrate enhanced grid regulation capacities of variable speed hydropower units. The targeted high flexibility operation modes imply increased numbers of start and stop cycles, frequent off-design operation and even power reversions. Thereby, the understanding of fatigue mechanisms at off-design conditions and during transitions is crucial to ensure safe long term flexibility operation of hydropower units. The present paper aims to investigate spatial and temporal discretization uncertainties of numerical flow and fatigue damage simulations. For a selected off-design operating point in turbine mode, unsteady CFD simulations and one way coupled FSI simulations are carried out to reveal stress fluctuations and fatigue damage on the Francis pump-turbine runner. First, a classical Grid Convergence Index (GCI) methodology is carried out. Moreover, a design of experiments methodology is applied, comprising a fractional factorial plan, to evaluate the individual effects from the guide vane, runner, and draft tube grid sizes as well as the simulation time step on the flow and fatigue damage results. The guide vane grid size is found to be the most impactful on torque, discharge, and efficiency results. The correlation of the grid sizes with the fatigue damage responses shows less pronounced statistical evidence. Nevertheless, the study reveals expectable numerical error ranges related to discretization uncertainties of runner fatigue damage simulations within practicable grid size and time step ranges.

CFD and FEM analysis to migrate from fixed- to variable-speed on the Alto Lindoso HPP

Conference ArODES

Olivier Pacot, Joachim Delannoy, François André, Claire Segoufin, João Delgado, Miguel Roque, Cécile Münch-Alligné

IOP Conference Series: Earth and Environmental Science ; Proceedings of the 31st IAHR Symposium on Hydraulic Machinery and Systems, 26 June-1st July 2022, Trondheim, Norway

Summary:

The need to decarbonise our energy system push us toward the use of different clean renewable energy sources, such as solar, wind and hydroelectric energy. It is well known that some of these renewable energy sources suffer of intermittence, which requires the conventional dispatchable power plants to become more flexible to respond to any power change to ensure a stable electrical grid. For this specific purpose, the European project XFLEX HYDRO is focusing on the hydropower sector, with seven demonstrators in three different countries to demonstrate the possibility to enhance the flexibility, one option being to use the variable-speed technology combined with smart digital control. Among these seven demonstrators, one is the Alto Lindoso hydropower plant owned by EDP and located in North-West of Portugal. It consists of two fixed-speed vertical Francis turbines with a high head of approximately 275 m and a rated power of 317 MW. The objective of this demonstrator is to assess the potential of a variable speed using the Doubly Fed Induction Machine (DFIM) technology to increase the flexibility of the power and the lifetime of the turbine. Therefore, this paper explores numerically the hydraulic behaviour of the model runner when operated at a selected part load conditions (60% BEP) with the rotational speed changed by ±10%. Second, a FEM analysis is carried out to evaluate the runner blades damage rate. This preliminary study showed that in term of wear and tear, the variable speed technology would bring in an advantage.

Eigenfrequencies of rotating discs in dense fluid :

Conference ArODES

imposed modal motion approach

Bernd Nennemann, Christine Monette, Olivier Braun, Daniel Biner, Cécile Münch-Alligné

IOP Conference Series: Earth and Environmental Science ; Proceedings of the 31st IAHR Symposium on Hydraulic Machinery and Systems, 26 June-1st July 2022, Trondheim, Norway

Summary:

The mode split on disc like structures rotating in a dense fluid leads to a deviation of eigenfrequencies at high rotational speeds compared to their values in still water. Predicting eigenfrequencies correctly is essential to avoid fatigue cracks on prototype turbine runners. Analytical models for simple geometric configurations and complex numerical models using fully coupled fluid structure interaction to predict the mode split on arbitrary geometries exist. We are presenting a complementary approach of intermediate complexity applicable to arbitrary geometries. Mode shapes and modal parameters are computed by finite element analysis in still water. These mode shapes are imposed with a harmonic variation in time during an unsteady computational fluid dynamics computation. From the interaction between the flow and the modal motion, the modal force and the modal work can be computed. These can be converted into added modal mass and hydrodynamic damping and further into the shift of the eigenfrequency under rotation due to the fluid for a given mode. The tendencies of the frequencies with rotation compare reasonably well with experimental data. The numerical method can be applied to disc rotation speeds far beyond the range of experimental data revealing interesting tendencies and a phenomenological interpretation of the cause of the mode split.

Optimization of turbine start-up sequence of a full size frequency converter variable speed pump-turbine

Conference ArODES

Jeremy Schmid, Sébastien Alligné, Daniel Biner, Cécile Münch-Alligné, N. Hugo, Christophe Nicolet

IOP Conference Series: Earth and Environmental Science ; Proceedings of the 31st IAHR Symposium on Hydraulic Machinery and Systems, 26 June-1st July 2022, Trondheim, Norway

Summary:

The stability of the electricity grid will be disrupted by the massive integration of new renewable energies. Hydropower plants have a major role to play in this transformation of the electricity market by increasing their operational flexibility and their ability to provide ancillary services. However, this flexibility may lead to an accelerated degradation of mechanical components. By changing the turbine operating point far from the best efficiency point or by increasing the number of transient manoeuvres such as start and stop sequences, unsteady flow phenomena, cavitation development and additional wear and tear stress the unit's components and impact its lifetime. The present work aims to provide preliminary insight on the optimization of the start-up sequence of a 5 MW reversible Francis pump-turbine equipped with a Full Size Frequency Converter (FSFC). The goal of the optimization approaches are to determine a start-up sequence which minimizes the runner damage, the penstock fatigue and the water losses. The objective functions are evaluated by 1D hydraulic transient simulations with the SIMSEN software and which it allow to compare the relative mitigation between the conventional fixed-speed start-up and the linear variable-speed start-up equipped with a Full Size Frequency Converter.

Numerical fatigue damage analysis of a variable speed Francis pump-turbine during start-up in generating mode

Conference ArODES

Daniel Biner, Sébastien Alligné, Christophe Nicolet, Drazen Dujic, Cécile Münch-Alligné

IOP Conference Series: Earth and Environmental Science ; Proceedings of the 31st IAHR Symposium on Hydraulic Machinery and Systems, 26 June-1st July 2022, Trondheim, Norway

Summary:

Variable speed hydropower units offer a large spectrum of grid regulation services and may therefore contribute to the stability of future power supply systems. Full Size Frequency Converters (FSFC) already found real world application in Pumped Storage Hydropower Plants up to a rated power of 100 MW and are even considered scalable up to a few hundred MW. Apart from the extension of the power range and grid regulation capacities, the FSFC technology also provides new control possibilities during transient operations such as start-up in generating mode. Thus, harsh conditions with damaging impact on the hydromechanical components may be avoided by tuning the operating point trajectory in the start-up phase. In this paper, runner fatigue damage during start-up in generating mode of a 5 MW variable speed Francis pump-turbine prototype equipped with a FSFC is numerically analyzed. The fixed speed solution is compared to a variable speed solution following a BEP tracking control strategy. 1D hydraulic transient simulations provide boundary conditions for detailed 3-D CFD/FEA simulations. Full and reduced numerical domains are used and compared. The overall outcome of the present numerical study indicates an important reduction of partial damages using variable speed drives for turbine start-up manoeuvres.

On-site measurements of the dynamic behaviour of Pelton turbines in the context of predictive maintenance

Conference ArODES

Maxime Chiarelli, Vlad Hasmatuchi, Ali Amini, Jean Decaix, David Florian Vetsch, Robert M. Boes, Cécile Münch-Alligné

IOP Conference Series: Earth and Environmental Science ; Proceedings of the 31st IAHR Symposium on Hydraulic Machinery and Systems, 26 June-1st July 2022, Trondheim, Norway

Summary:

The operating modes of pumped storage power plants, such as that of the Forces Motrices Hongrin-Léman (FMHL) in Switzerland, have drastically changed over the past decades due to the emergence of new renewable energies. The number of starts and stops experienced by machines increased significantly leading to broader fatigue cycles on the different parts of the machine. Therefore, the development of predictive maintenance tools is paramount to increase the availability and reinforce operational safety of the power plant. In this context, vibration measurements were performed on a 60 MW Pelton turbine of one of the ternary units of the FMHL power plant during dynamic and steady state operations. Non intrusive instrumentation has been deployed including accelerometers on the bearing. Comparing the ramp-up and ramp-down of the Pelton turbine, a hysteresis of the vibration level for a similar power has been observed. A reduction of the vibration levels when an additional injector is engaged during the ramp-up is observed. This reduction correlates strongly with the load reduction on the buckets when the total flow rate is distributed over more injectors, leading to a smaller flow rate per injector.

Development of a novel cavitation monitoring system for hydro turbines based on machine learning algorithms

Conference ArODES

Ali Amini, Olivier Pacot, Dominique Voide, Vlad Hasmatuchi, Pierre Roduit, Cécile Münch-Alligné

IOP Conference Series: Earth and Environmental Science ; Proceedings of the 31st IAHR Symposium on Hydraulic Machinery and Systems, 26 June-1st July 2022, Trondheim, Norway

Summary:

Operating hydro turbines in off-design conditions increases the risk of cavitation occurrence, which in turn, leads to numerous problems such as performance degradations, structural vibrations, and most importantly, mechanical damage due to erosion. It is therefore crucial to develop a monitoring system that detects the occurrence and severity of cavitation in real time. For this purpose, a cavitation detection methodology has been developed that is based on the analysis of acoustic emissions of a turbine with machine learning algorithms. In this method, a conventional microphone is used to record the airborne noise emitted from a turbine under different working conditions, and then, a supervised learning algorithm is trained to classify the recorded noise signals into cavitating and non-cavitating categories. The detection system was developed based on laboratory tests and was validated in Ernen hydropower plant located in Canton of Wallis in southeast of Switzerland. This power plant consists of two identical double-flux Francis turbines each having a maximum power of 16 MW and a net head of 270 mWC. The preliminary results obtained from a two-day experimental campaign in the Ernen powerplant are very promising in terms of cavitation detection with a classification accuracy of more than 90 %. The system could be implemented either for real-time monitoring of cavitation occurrence allowing the operators to avoid such a condition or as a post processing tool to evaluate the number of hours a turbine has worked under severe conditions. Work is still ongoing to deploy more complex learning algorithms for this task to minimize expert intervention and/or interpretation during the setup process.

CFD simulations of hydraulic short-circuits in junctions, application to the Grand’Maison power plant

Conference ArODES

Jean Decaix, Jean-Louis Drommi, François Avellan, Cécile Münch-Alligné

IOP Conference Series: Earth and Environmental Science ; Proceedings of the 31st IAHR Symposium on Hydraulic Machinery and Systems, 26 June-1st July 2022, Trondheim, Norway

Summary:

In the framework of the XFLEX HYDRO H2020 European Project, the pumped storage power plant of Grand’Maison (France), owned by Electricit´e De France, focuses on the implementation of the hydraulic short-circuit (HSC) operating mode. This mode increases the flexibility in pumping mode, which helps the integration of intermittent energies. Grand’Maison is divided into two power houses: the first features four Pelton turbine units and the second eight reversible pump-turbines units. A trifurcation splits the flow into three penstocks, each is then split into two branches that feed each power house. The HSC operating mode, which consists in operating the pumps and the Pelton turbines simultaneously, changes the flow paths in the junctions compared to the pump mode. The power plant was not designed to operate in HSC mode over a long duration, therefore an assessment of its feasibility is necessary. 151 computational fluid dynamic simulations are carried out for two bifurcations and one trifurcation. The numerical simulation results show that the local head losses in HSC mode represent less than 1% of the gross head. No flow instabilities are observed at the bifurcations contrary to the trifurcation. Additional analyses are required to better understand the flow in the trifurcation.

2021

Case studies of small pumped storage

Conference ArODES

Olivier Pacot, Shadya Martignoni, Laurent Smati, Vincent Denis, Cécile Münch-Alligné

Proceedings of HydroEs 2021, 22-24 September, Lyon, France

Summary:

Energy storage through pumped-storage (PSP) hydropower plants is currently the only mature large-scale electricity storage solution with a global installed capacity of over 100 GW. The objective of this study is to evaluate the possibility of using this storage solution on a smaller scale to provide local voltage control and line congestion management to active medium voltage distribution networks. First, several potential sites were identified in the French-speaking part of Switzerland, ideally with existing reservoirs. Following a selection of the most promising sites, two are selected to presize the various components and estimate the investment costs. These two sites are located in the Val de Bagnes in the canton of Valais in Switzerland and offer hydraulic powers of approximately 5 and 10MW. The approximation of the investment cost is around 2 CHF /Watt. In comparison with recent large hydropower projects these prices seem quite reasonable given that the investment cost for large hydropower is of the order of 2-3 CHF/Watt. In parallel, a free software (“freeware”) to evaluate the potential, to select the components and to estimate the costs was developed to facilitate future studies.

Effect of the variable speed on the hydraulic behavior of the caniçada francis turbine

Conference ArODES

Olivier Pacot, Thomas de Colombel, Claire Segoufin, Joachim Delannoy, Sebastian Leguizamon, João Delgado, Miguel Roque, Cécile Münch-Alligné

Proceedings of SimHydro 2021: Models for complex and global water issues - practices and expectations, 16-18 June 2021, Sophia Antipolis, France

Summary:

The need to decarbonize our energy production push us toward the use of renewable sources such as solar, wind and hydraulic energies. These renewable energies often suffer from intermittences which requires flexibility from the dispatchable energy producers to respond to power changes and to ensure a stable electrical grid. For this specific purpose, the European project XFLEX HYDRO is focusing on the hydropower sector, with seven demonstrators in three different countries to determine the advantages of variable- and fixed-speed turbine, smart control, and hybrid batteryturbine systems. Among these seven demonstrators, the hydropower plant of Caniçada operated by EDP consists of two fixed-speed vertical Francis turbines with a medium head of approximately 100 meters and a total installed power of 70 MW. The objective of this demonstrator is to assess the potential of a variable speed technology to increase the lifetime of the turbine. For this purpose, we investigated here in a first time the hydraulic behaviour of the machine when operated at part load conditions with a fixed runner speed to find the operating condition generating the maximum pressure fluctuations. In a second time, we analysed the advantages of variable-speed capabilities regarding this operating condition. The study is carried out with CFD analysis using ANSYS CFX and the SST turbulence model. The results show a clear amelioration of the pressure fluctuations on the runner with variable speed however mitigated with a lowering of efficiency for this operating point.

Numerical simulations for multipurpose reservoirs for alpine irrigation

Conference ArODES

Théo Gonin, Jean Decaix, Jérémy Schmid, Alexandre Gillioz, Damien Pettinaroli, Cécile Münch-Alligné

Proceedings of SimHydro 2021: Models for complex and global water issues - practices and expectations, 16-18 June 2021, Sophia Antipolis, France

Summary:

In most of the Swiss Alpine regions, the availability of water resources for irrigation is usually adequate, even in period of drought, as evidenced by the summers of 2003 and 2018. Indeed, important natural stocks are for the moment available in the form of snow and ice, but the situation is likely to change in the future considering global and regional climate change. The municipality of Val de Bagnes located in the canton of Valais, Switzerland, is a region where water is a very important economic factor used for hydropower, winter and summer tourism and agriculture. The study will make it possible to apprehend the needs and future availabilities for irrigation water, by 2050 and 2085, and to plan as soon as possible the modifications required to the water supply or distribution networks. This article focuses on the modeling and simulation of future scenarios of the water network. The results are based on the principle of deficit on the water demand compared to the available water in the adduction network. To illustrate the influence of the climate change on these deficits, simulations based on RCP scenarios have been run for years 2050 and 2085. The current network configuration seems to be suitable for the demand and the variability of the input until 2050. Nevertheless, for the 2085 forecasts, the existing network would not be able to match the demand. This study shows that a regional interdisciplinary approach between the technical, agricultural and social fields is necessary to manage water resources in the future even in Alpine regions where no extreme water stress is observed today.

Numerical simulation of the interaction between the jet and a pelton runner under low head

Conference ArODES

Jean Decaix, Anthony Gaspoz, Steve Crettenand, Cécile Münch-Alligné

Proceedings of SimHydro 2021: Models for complex and global water issues - practices and expectations, 16-18 June 2021, Sophia Antipolis, France

Summary:

In Switzerland, during the last decade, the development of the new renewable energies (small hydro, solar, wind…) has been promoted by a specific feed-in tariff. However, the regulator schedules to remove this specific measure to force the producers to match the demand. Regarding the small hydropower plants, this change requires to increase the flexibility of the power plants. The present work focuses on the hydro power plant of Gletsch-Oberwald (KWGO, Valais, Switzerland), a run-of-river power plant equipped with two six-jet Pelton turbines. An extension of the flexibility of the power plant is investigated in the framework of the SmallFlex project by using one-third of the headrace tunnel as a storage volume. The use of this new storage capacity would require emptying the headrace tunnel and to operate the Pelton turbines at a lower head than the one for which they have been designed. By lowering the head, the efficiency of the Pelton turbines will decrease abruptly if the Pelton turbines make faces to the so-called “falaise” effect. Before performing on-site measurements, unsteady two-phase flow simulations of the interaction between the jet and the Pelton runner have been carried out for four different heads with the Ansys CFX software. At the best efficiency point, the efficiency is well predicted by the simulation. For lower heads, the interaction between two consecutive jets is observed but the decrease in efficiency is underestimated compared to the on-site measurements.

Production flexibility of small run-of-river power plants :

Conference ArODES

KWGO smart-storage case study

Cécile Münch-Alligné, Jean Decaix, Anthony Gaspoz, Vlad Hasmatuchi, Matthieu Dreyer, Christophe Nicolet, Siamak Alimirzazadeh, Jessica Zordan, Pedro Manso, S. Crettenand

IOP Conference Series: Earth and Environmental Science ; Proceedings of 30th IAHR Symposium on Hydraulic Machinery and Systems (IAHR 2020) 21-26 March 2021, Lausanne, Switzerland

Summary:

In the framework of the new Swiss feed-in-tariff system for Small Hydropower Plants (SHP), the aim of the SmallFLEX project, led by HES-SO Valais and performed in collaboration with EPFL, WSL, EAWAG, PVE and FMV, is to show how SHP can provide winter peak energy and ancillary services, whilst remaining eco-compatible. The pilot and demonstrator site selected is the new SHP of Gletsch-Oberwald (KWGO) owned by FMV and commissioned end of 2017. This run-of-river power plant is equipped with two six-jets Pelton turbine units featuring a maximum power of 7.5 MW each while the average annual power is lower than 5 MW, with a maximum of production during the summer. The capacity of infrastructure, equipment, and other adaptation measures to produce in a flexible way is being assessed while measuring the impact of this new operation on the environment, production and revenues. The paper focuses on the two experimental campaigns and the numerical simulations carried out to assess the flexibility of the power plant by means of smart use of existing infrastructure as additional storage volumes: the settling basin, the forebay and the upper part of the headrace tunnel.

Numerical simulations of Pelton turbine flow to predict large head variation influence

Conference ArODES

Siamak Alimirzazadeh, Jean Decaix, François Avellan, S. Crettenand, Cécile Münch-Alligné

IOP Conference Series: Earth and Environmental Science ; Proceedings of 30th IAHR Symposium on Hydraulic Machinery and Systems (IAHR 2020), 21-26 March 2021, Lausanne, Switzerland

Summary:

In the framework of the new feed-in-tariff system in Switzerland for Small Hydropower Plants (SHP), the aim of the SmallFLEX project, led by HES-SO Valais and performed in collaboration with EPFL, WSL, EAWAG, PVE, and FMV, is to show how SHP can provide winter peak energy and ancillary services, whilst remaining eco-compatible. The pilot and demonstrator site selected is the new small hydropower plant of Gletsch-Oberwald (KWGO) owned by FMV and commissioned end of 2017. This run-of-river power plant is equipped with two six-jet Pelton turbine units featuring a maximum power of 7 MW each. The addition of flexibility can be reached by using existing volumes of the power plant: the settling basin, the forebay chamber as well as part of the headrace tunnel. By consequence, the turbine head will undergo variations. To ensure that these variations will not cause any damages to the Pelton runner, the influence of the available head is investigated by numerical simulations. The simulations are carried out using two different software. OpenFOAM, which is based on a Finite Volume Method (FVM), is used for computing the flow inside the distributor until the jet. GPU-SPHEROS, which is based on Arbitrary Lagrangian-Eulerian (ALE) Finite Volume Particle Method (FVPM) is utilized to compute the interaction between the jet and Pelton buckets. Mixing the two aforementioned approaches, i.e. mesh-based FVM and particle-based FVPM, the overall torque T of the present six-jet Pelton runner can be reconstructed for different rated heads and discharges. The predicted torque fluctuations can then be considered for an estimation of the structural fatigue damage of the runner.

Turbine mode start-up simulation of a FSFC variable speed pump-turbine prototype :

Conference ArODES

Part I: 1D simulation

S. Alligné, A. Béguin, Daniel Biner, Cécile Münch-Alligné, Vlad Hasmatuchi, N. Hugo, François Avellan, D. Dujic, C. Nicolet

IOP Conference Series: Earth and Environmental Science ; Proceedings of 30th IAHR Symposium on Hydraulic Machinery and Systems (IAHR 2020), 21-26 March 2021, Lausanne, Switzerland

Summary:

Variable speed hydroelectric units equipped with full size frequency converter (FSFC) offer high operational flexibility enabling fast operating point transitions which increase grid regulation capacities. The XFLEX HYDRO H2020 European research project aims to demonstrate flexibility of such technology at prototype scale. The Z'Mutt pumping station, part of the Grande Dixence hydroelectric scheme located in Switzerland, is one of the demonstrators focused on the FSFC technology with a new 5 MW reversible Francis pump-turbine which will be commissioned in 2021. This paper, divided in two parts, aims to simulate the turbine mode fast start-up sequence made possible with the use of a FSFC and to assess the unit damage by means of 1D and 3D CFD simulations. The part I of this paper presents the 1D hydraulic transient simulation results of start-up sequences of unit U5 considering both conventional fixed speed technology and variable speed technology. The time evolution of the unit's operating point is used as input data for 3D CFD simulations of part II, aiming to assess the impeller damage. Different control strategies to use the FSFC for turbine mode start-up sequence are analysed. Advantages and limits of each strategy are discussed, and recommendation is made for the Z'Mutt prototype demonstrator.

Turbine mode start-up simulation of a variable speed Francis pump-turbine prototype :

Conference ArODES

Part II: 3-D unsteady CFD and FEM

Daniel Biner, S. Alligné, Vlad Hasmatuchi, C. Nicolet, N. Hugo, François Avellan, D. Dujic, Cécile Münch-Alligné

IOP Conference Series: Earth and Environmental Science ; Proceedings of 30th IAHR Symposium on Hydraulic Machinery and Systems (IAHR 2020), 21-26 March 2021, Lausanne, Switzerland

Summary:

The Z'Mutt pumping station, part of the Grande Dixence hydroelectric scheme, is one of the demonstrators of the XFLEX HYDRO project. A 5 MW reversible pump-turbine prototype equipped with a full-size frequency converter (FSFC) is used to investigate dynamic variable speed operation in pumping and generating mode. Since the FSFC converter is always connected to the electrical grid, the full rotational speed range of the motor-generator can theoretically be exploited. Furthermore, this technology enables fast operating point transitions and therefore increased grid regulation capacities. The advantages of the FSFC technology in generating mode are compared to a conventional fixed speed start-up with a variable speed start-up. The operating point trajectories are extracted from 1-D hydraulic transient simulations. Detailed hydrodynamic and structural aspects of the pump-turbine during the two start-up scenarios are further studied. Simplified unsteady 3-D CFD simulations and transient structural FEM analyses of the pump-turbine prototype are carried out to assess the harshness of the flow and to anticipate runner fatigue. The present work aims to point out potential mitigation of partial runner damages during start-up in generating mode using FSFC technology.

CFD simulations of a Y-junction for the implementation of hydraulic short-circuit operating mode

Conference ArODES

Jean Decaix, Daniel Biner, J.-L. Drommi, François Avellan, Cécile Münch-Alligné

IOP Conference Series: Earth and Environmental Science ; Proceedings of 30th IAHR Symposium on Hydraulic Machinery and Systems (IAHR 2020), 21-26 March 2021, Lausanne, Switzerland

Summary:

In the framework of the XFLEX HYDRO H2020 European Project, one of the demonstrators focuses on the implementation of the hydraulic short-circuit on the pump storage power plant of Grand-Maison owned by Electricité De France (EDF). The Grand-Maison power plant is a two-level plant production with one plant located above the downstream reservoir and equipped with four Pelton turbines; a second plant located downstream the reservoir and equipped with eight reversible pump-turbines. Hydraulic short circuit consists in running pumps and turbines in the meantime to balance the energy consumption of the pumps compared to the grid. Such an operating mode allows increasing the flexibility of the power plant and targeting the requirement of balancing the intermittent production due to the growing of new renewable energies such as wind and solar power plants. The hydraulic short-circuit operating mode leads to a change in the flow paths in the penstocks and junctions compared to the normal turbine or pump modes. Indeed, compared to the pump mode, this mode will lead to a flow derivation at the junction between the penstocks directed to the Pelton units and the penstocks directed to the upper reservoir. As this mode have not been scheduled at the beginning of the power plant construction, it is necessary to quantitatively assess the singular head losses generated at the junction to be able to simulate the complete behaviour of the power plant by means of a 1D model. CFD simulations are carried out with the Fluent software for several configurations of hydraulic short-circuit defined by the ratio of flow rate deviated to the Pelton turbines.

2020

Towards the non-intrusive detection and monitoring of cavitation in hydraulic machines

Conference

Hasmatuchi Vlad Constantin, Pedroni François, Biner Daniel, Decaix Jean, Gino Blommaert, Münch-Alligné Cécile

Hydro2020, 26.10.2020 - 28.10.2020, Strasbourg

2019

Cost-effective CFD simulation to predict the performance of a hydrokinetic turbine farm

Conference ArODES

Oliver Pacot, Damien Pettinaroli, Jean Decaix, Cécile Münch-Alligné

IOP Conference Series: Earth and Environmental Science ; Proceedings of IAHR International Workshop on Cavitation and Dynamics Problems in Hydraulic Machinery and Systems, 9-11 October 2019, Stuttgart, Germany

Summary:

2018

On-board measurements at a 100MW high-head Francis turbine

Conference ArODES

Maximilian Titzschkau, Vlad Hasmatuchi, Jean Decaix, Cécile Münch-Alligné

Proceedings of 20th International Seminar on Hydropower Plants, 14 - 16 November 2018, Vienna, Austria

Summary:

The Francis turbine runners of the four ternary groups of Grimsel 2 power plant in Switzerland showed fatigue cracks at the runner blades much earlier than expected. To find the source of these cracks, strain gauges and accelerometers were used to get information about the harmful stresses on the runner during operation. It is observed that the speed no-load operation during the start-up and the shutdown processes of the turbine impose large stresses on the runner blades.

Experimental and numerical investigations of high-head pumped-storage power plant at speed no-load

Conference ArODES

Jean Decaix, Vlad Hasmatuchi, Maximilian Titzschkau, Laurent Rapillard, Pedro Manso, François Avellan, Cécile Münch-Alligné

Proceedings of 29th IAHR Symposium on Hydraulic Machinery and Systems, 16-21 September 2018, Kyoto, Japan

Summary:

Due to the increasing integration of new renewable energies, the electrical grid undergoes more frequent instabilities. Hydroelectric power plants, particularly pumped storage plants, are well suited for grid control. However, this objective requires extending the operating range of the machines and increasing the number of start-up, stand-by and shut-down procedures, which reduces the lifespan of the machines due to high mechanical stresses. The current study focuses on a pumped-storage power plant equipped with ternary groups. Recently, cracks on the runner blades of the Francis turbine have been observed without finding a clear explanation for their onset. During this period, the number of starts and stops per day has strongly increased. In order to better understand the origin of the fatigue of the turbine runner, external and on-board measurements along with CFD and FEM investigations have been performed. The on-board measurements provide evidence high mechanical stresses on the runner blades during the synchronization of the machine at speed no-load (SNL) operating condition. The frequency spectrum observed on the various signals suggests that the high stresses are linked to the excitation of one of the runner modes by some flow instabilities, which is supported by the CFD and FEM analyses.

2017

Design of a PM-generator for a straight flow counter-rotating micro-hydro turbine

Conference ArODES

Domenico Violante, Cécile Münch-Alligné, Samuel Chevailler, Lucas Farner

Proceedings of 2017 19th European Conference on Power Electronics and Applications (EPE'17 ECCE Europe), 11-14 September 2017, Warsaw, Poland

Summary:

This paper presents the design and the measurement of two identical PM-generators driven by an axial counter-rotating micro-turbine, called DuoTurbo-microturbine. This prototype for drinking water networks has been jointly developed by the HES-SO Valais//Wallis, the EPFL-Laboratory for Hydraulic Machines and industrial partners. The modular in-line “plug & play” technology requires low investment, reaching economic feasibility with an available power between 5 kW and 25 kW. One stage of the microturbine consists of two axial counter-rotating runners that form a compact independent unit. Each runner of the turbine holds its own rim generator, the DuoTurbo-configuration involving that each hydraulic runner is integral with each electrical rotor [1].

New prototype of a kinetic turbine for artificial channels

Conference ArODES

Cécile Münch-Alligné, Sylvain Richard, Anthony Gaspoz, Vlad Hasmatuchi, Nino Brunner

Proceedings of SimHydro 2017: Choosing the right model in applied hydraulics, 14-16 June 2017, Sophia Antipolis, France

Summary:

In the actual context of Swiss nuclear phase-out stategy, harvesting the extensive potential of small hydropower (<10MW), in particular on existing infrastructure, is a priority. In this framework, a new kinetic turbine has been jointly developed between the HES-SO Valais/Wallis and Stahleinbau Gmbh in SwitzerlandIn the actual context of Swiss nuclear phase-out strategy, harvesting the extensive potential of small hydropower (<10MW), in particular on existing infrastructure, is a priority. In this framework, a new kinetic turbine has been jointly developed between the HES-SO Valais//Wallis and Stahleinbau Gmbh in Switzerland, to harvest the kinetic energy of free surface flows in existing facilities such as run-of-river tailrace channels, headrace tunnels or water treatment stations. The hydraulic design of the ducted turbine has been obtained by flow numerical simulations. The objective of the present research project is to build a first prototype of 1 kW as well as an open-air platform and to test it in a tailrace channel. The chosen pilot site is the Lavey run-of-river hydropower plant’s tailrace channel, installed in the Western side of Switzerland on the Rhône River. The final purpose is to confirm the hydraulic efficiency results obtained by simulation and the electro-mechanical concept in view of a product industrialization phase to tap this potential in Switzerland and elsewhere. The global concept of the variable speed prototype, including the actual hydraulic and mechanical design, the electrical generator and the driving electronics as well as the integrated instrumentation are first presented. The specially designed open-air testing platform to test the turbine in the channel is also introduced. Finally, the efficiency of the turbine is optimized using steady pressurized numerical simulations and assessed in case of unsteady homogeneous multiphase turbulent simulations in the tailrace channel of Lavey. A power coefficient higher than 80% is reached.

2016

Performance measurements on the DuoTurbo microturbine for drinking water systems

Conference ArODES

Vlad Hasmatuchi, D. Biner, François Avellan, Cécile Münch-Alligné

Proceedings of the HYDRO 2016 conference, 10-12 October 2016, Montreux, Switzerland

Dynamic efficiency measurements on hydraulic turbomachinery model testing :

Conference ArODES

examples of implementation and validation

Vlad Hasmatuchi, Alin Bosioch, Sébastien Luisier, Cécile Münch-Alligné

Proceedings of 11th International conference on hydraulic efficiency measurement (IGHEM 2016), 24-26 August 2016, Linz, Austria

Summary:

The implementation of the so-called "sliding-gate" dynamic method to measure in a faster way (up to ten times) the efficiency characteristics on hydraulic turbomachinery is presented. The new model testing measurement method is successfully applied on two different cases dedicated to recover the energy lost in release valves of water supply networks: a 2.65 kW double-regulated laboratory prototype of an in-line axial microturbine with two independent variable speed counter-rotating runners; a 11kW multi-stage centrifugal pump as turbine (PAT) with varaible speed. The universal test rig of the HES-SO Valais/Wallis, Switzerland, dedicated to asses hydraulic performances of small-power turbomachines, has been employed. The applied procedure consists, in a first step, on measuring the 3D hill-chart of a given testing model (turbine or pump) by the classical static point-by-point method. Then, a second digitizer is added to acquire synchronized dynamic signals of the sensors in parallel with the existing acquisition/control system of the test rig. The dynamic measurements of efficiency are performed at different constant speeds of the test rig recirculating pumps while increasing and/or decreasing the speed of the testing model runner(s) from zero to maximum, and vice versa, slowly enough in order to keep a steady-state operation. In the end, the resulting 3D efficiency hill-charts of the two tested machines obtained by the dynamic and by the classical static point-by-point measurement methods are compared, with the measurement precision and repeatability particularly emphasized.

2015

Identification of the wave speed and the second viscosity of cavitation flows with 2D RANS computations - Part I

Conference ArODES

Jean Decaix, S. Alligné, Christophe Nicolet, François Avellan, Cécile Münch-Alligné

Proceedings of 9th International Symposium on Cavitation (CAV2015), 6–10 December 2015, Lausanne, Switzerland ; Journal of Physics: Conference Series

Summary:

1D hydro-electric models are useful to predict dynamic behaviour of hydro-power plants. Regarding vortex rope and cavitation surge in Francis turbines, the 1D models require some inputs that can be provided by numerical simulations. In this paper, a 2D cavitating Venturi is considered. URANS computations are performed to investigate the dynamic behaviour of the cavitation sheet depending on the frequency variation of the outlet pressure. The results are used to calibrate and to assess the reliability of the 1D models.

Identification of the wave speed and the second viscosity in cavitating flow with 2D RANS computations - Part II

Conference ArODES

Sébastien Alligné, Jean Decaix, Christophe Nicolet, François Avellan, Cécile Münch-Alligné

Proceedings of Journal of the 9th International Symposium on Cavitation (CAV2015), 6–10 December 2015, Lausanne, Switzerland ; Physics: Conference Series

Summary:

The 1D modelling of cavitation vortex rope dynamics in Francis turbine draft tube is decisive for prediction of pressure fluctuations in the system. However, models are defined with parameters which values must be quantified either experimentally or numerically. In this paper a methodology based on CFD simulations is setup to identify these parameters by exciting the flow through outlet boundary condition. A simplified test case is considered to assess if 1D cavitation model parameters can be identified from CFD simulations. It is shown that a low wave speed and a second viscosity due to the cavitating flow can be identified.

Hydraulic performance of a new isokinetic turbine for rivers and artificial channels

Conference ArODES

Vlad Hasmatuchi, Sébastien Alligné, Jean-Louis Kueny, Cécile Münch-Alligné

E-Proceedings of the 36th IAHR World Congress, 28 June-3 July 2015, The Hague, the Netherlands

Summary:

A new ducted isokinetic turbine for rivers and artificial channels has been designed. The new (patented) concept consists on an axial turbine with two joined concentric runners: an annular turbine runner and a central pump runner. The aim of the pump runner is to induce a suction effect in the central area in order to increase the axial velocity passing through the turbine runner and consequently the hydraulic efficiency. In a first step, steady incompressible monophasic turbulent flow (k-ε model) numerical simulations have been used to optimize the hydraulic profile of a turbine with an expected mechanical power of 1 kW. A reduced computational domain including only a periodic quart of the turbine (at prototype scale) immerged in a water box has been considered. The Fine/Turbo package of the Numeca commercial code has been employed to solve the RANS equations using the finite volume method. Then, numerical simulations of unsteady incompressible homogeneous multiphase turbulent flow (using the SST model) have been performed on a computational domain including the full water passage of the final prototype, placed in a in a run-of-river tailrace canal with trapezoidal cross-section, to recover its hydraulic efficiency. The URANS equations have been solved with the Ansys CFX 14.5.7 commercial code using the finite volume method. The main contribution of this work consists on a successful implementation of the numerical tools to optimize and to recover the hydraulic efficiency of a new isokinetic turbine with and without the free-surface effects taken into account. Moreover, the effect of the pump runner is assessed by comparing the obtained efficiency with performances of the isokinetic turbine featuring a free central open passage.

New hydraulic test rig for small-power turbomachines

Conference ArODES

Vlad Hasmatuchi, Francisco Botero, Shadya Grabathuler, Cécile Münch-Alligné

E-Proceedings of the 36th IAHR World Congress, 28 June-3 July 2015, The Hague, the Netherlands

Summary:

A new universal test rig has been installed at the HES-SO VS Sion - Switzerland to assess the hydraulic performances of different types of small-power turbomachines (up to 10 kW) and other hydraulic components with complex geometry, following the IEC 60193 standard recommendations. The closed-loop circuit allows simulating different implantation levels of the model and therefore recovering the cavitation performances as well. The present work introduces a state-of-the-art approach of an automatic regulation for hydraulic test rigs. An autonomous regulation system based on real-time measurements is developed using the capabilities of a National Instruments compact Reconfigurable Input Output device. Indeed, during operation, the system can keep constant the value of the desired parameters (e.g. testing head, discharge, pumps speed, Thoma number, etc.). Then, the implemented wireless communication architecture between the hydraulic test rig and further measurements/monitoring systems offers flexibility. Moreover, the control system of the test rig manages a dedicated cloud of variables and shares it with the client systems. Finally, this approach ensures safe data centralization and storage on hydraulic turbomachinery model testing.

Design & performance of a hydraulic micro-turbine with counter-rotating runners

Conference ArODES

Daniel Biner, Vlad Hasmatuchi, François Avellan, Cécile Münch-Alligné

Proceedings of 2015 5th International Youth Conference on Energy (IYCE), 27-30 May 2015, Pisa, Italy

Summary:

The largely unexploited potential of small scale energy hydropower remains crucial the development of new technologies to harvest the hydraulic energy on existing facilities. In this framework, several projects have been set up by the HES-SO Valais//Wallis and the EPFL Laboratory for Hydraulic Machines. One of the developed technologies is a new hydraulic micro- turbine, for recovering the energy lost in release valves of water supply networks. One stage of the micro-turbine consists of two axial counter-rotating runners. This paper deals with the hydraulic design process of the runners for a given site, including numerical flow simulations, fabrication and performance measurements of the micro-turbine. An overview of theoretical basics, simulation settings and assumptions, simulation results and test results is given. In the last part, the design optimization process is discussed.

2014

Computational fluid dynamics as a tool to predict the air pollution dispersio in a neighborhood :

Conference ArODES

a research project to improve the quality of life in cities

Gilles Triscone, Nabil Abdennadher, Christophe Balistreri, Olivier Donzé, Davide Greco, Patrick Haas, Hasret Haas-Peköz, Tamer Mohamed-Nour, Pierre Munier, Piero Pontelandolfo, Roberto Putzu, Hervé Sthioul, Nicolas Delley, David Choffat, Elena-Lavinia Niederhäuser, Roger Schaer, Henning Müller, Jean Decaix, Sylvain Richard, Cécile Münch-Alligné, Pierre Kunz, Fabienne Despot

Proceedings of Smart city expo world congress 2014

Summary:

In large cities, pollution composed of many different chemical components and small particles is an important public health problem that affects especially children and people presenting breathing difficulties. One challenge for public authorities is to respect the norms given by the central state, but how? Today, concrete methods for reducing pollution are perceived by the majority of citizens as constraints. However, the authorities have the possibility of modifying the wind's action by imposing architectural constraints, such as building emplacement and roof structure. This is the main objective of the Geneva "Clean City" project financed by the University of Applied Sciences Western Switzerland. "Clean City" focuses its research on one of Geneva’s polluted neighborhoods called Pâquis which is situated directly on the Geneva lake front. The project attempts to understand the dispersion of pollution from an experimental and a numerical point of view. After validation of the technique for a simple case, we compare environmental measurements on a 1/500 3D scale model of the Pâquis installed in an instrumented wind tunnel with Computational Fluid Dynamics (CFD) simulation obtained with the help of cloud computing. In Barcelona, we will show the first experimental measurements and simulated “Clean City” results.

Development of a PM-generator for a counter-rotating micro-hydro turbine

Conference ArODES

David Melly, Rodolfo Horta, Cécile Münch-Alligné, Hans-Peter Biner, Samuel Chevailler

Proceedings of the 2014 International Conference on Electrical Machines (ICEM), 2-5 September 2014, Berlin, Germany

Summary:

Nowadays, a great effort is done to find new alternative renewable energy sources to replace part of nuclear energy production. In this context, this paper presents a new axial counter-rotating turbine for small-hydro applications which is developed to recover the energy lost in release valves of water supply. The design of the two PM-generators, their mechanical integration in a bulb placed into the water conduit and the AC-DC Vienna converter developed for these turbines are presented. The sensorless regulation of the two generators is also briefly discussed. Finally, measurements done on the 2-kW prototype are analyzed and compared with the simulation.

RANS computations of a cavitating tip vortex

Conference ArODES

Jean Decaix, Guillaume Balarac, Cécile Münch-Alligné

Proceedings of SimHydro 2014: Modelling of rapid transitory flows, 11-13 June 2014, Sophia Antipolis, France

Summary:

The Swiss national research project Hydronet 2 gathers a consortium of industrial and academic partners supported by the Competence Center of Energy and Mobility (CCEM) and Swiss Electric Research (SER) in order to improve the hydropower plants. One of the research topic focuses on the cavitating tip vortex. Such a vortex takes place in axial turbines as Kaplan turbines used for producing hydroelectricity. This phenomenon drives a lot of drawbacks such as erosion, unsteady flow rate and a decrease of the turbine efficiency. To better understand the behaviour of the tip vortex, computations of a simple test case are performed. The test case consists in a NACA profile mounted in a channel with a gap between the NACA tip and the lateral wall. The computations are carried out with the OpenFOAM solver both in one-phase and two-phase flow. The turbulent motion is modelled with a RANS approach. For the twophase flows computations, the phase change between liquid and vapour is achieved with the model proposed by Kunz. The results will be compared in cavitating and non cavitating cases with the experimental data provided by the EPFL Laboratory for Hydraulic Machines. The comparisons deal with global picture of the flow, the trajectory of the tip vortex and the velocity field downstream the NACA profile.

2012

Numerical simulation of a new sand trap flushing system

Conference ArODES

Milad Daneshvari, Cécile Münch-Alligné, Giovanni De Cesare

Proceedings of 4th IAHR Symposium on Hydraulic Structures, 9-11 February 2012, Porto, Portugal

Summary:

Typical sand trap flushing systems, such as Büchi and Dufour, require water volumes up to six times the deposited sediment volume for efficient flushing. Furthermore, complete sediment removal particularly in Dufour sand traps can only be realized with drawdown flushing, resulting in operation time and water loss. The objective of the described research project is to improve the flushing system of an existing Dufour sand trap. Numerical simulations, performed with two software packages ANSYS CFX and FLOW-3D, are carried out to investigate the flow dynamics in the flushing system and to investigate the required sediment flushing discharge. The flow in the existing flushing system is first studied to evaluate the actual performance of the system. Numerical simulations of the flow in the new flushing system, using the same sand trap, are performed to assess the induced improvements. A good agreement between the results of the numerical simulations using both software packages is observed. Regarding the velocity field in the flushing channel, the existing system is only efficient on the last third of the channel. In the new system, the velocity magnitude is sufficiently high all along the flushing conduit ensuring a good efficiency of the whole system.

2011

Development of a tidal current turbine

Conference ArODES

Cécile Münch-Alligné, M. Vonlanthen, J. Gomes, P. Guinard, François Avellan

Actes des Journées SHF: Cavitation et Machines Hydrauliques, 25-26 mai 2011, Lausanne, Suisse