Publications associées à Coup de bélier

Unsteady Flow Numerical Simulations on Internal Energy Dissipation for a Low-Head Centrifugal Pump at Part-Load Operating Conditions

Dredge pumps are usually operated at part-load conditions, in which the low-solidity centrifugal impeller could experience large internal energy dissipation, related to flow separation and vortices. In this study, SST k- and SAS-SST turbulence models were ...

2019

Characterization of hydraulic behavior of orifices in conduits

Nicolas Jean François Pascal Ghislain Adam

High-head power plants are the main pillar of Swiss peak electricity production. With the 2050 Energy Strategy approved by Swiss voters, the annual production of hydroelectricity should increase by 4%, while 90% of the technically feasible potential is alr ...

EPFL2017

An experimental study on flow boiling pressure drop in multi-microchannel evaporators with different refrigerants

John Richard Thome, Houxue Huang

A key parameter in designing two-phase flow systems for the cooling of high heat flux electronics is the pressure drop in microchannel evaporators. As a result, an experimental study was performed to investigate the flow boiling pressure drop of refrigeran ...

Elsevier Science Inc2017

Experimental evidence of inter-blade cavitation vortex development in Francis turbines at deep part load condition

François Avellan, Arthur Tristan Favrel, Keita Yamamoto

Francis turbines are subject to various types of cavitation flow depending on the operating condition. To enable a smooth integration of the renewable energy sources, hydraulic machines are now increasingly required to extend their operating range, especia ...

Springer Verlag2017

Simulation of pump-turbine prototype fast mode transition for grid stability support

François Avellan, Christophe Nicolet, Nicolas Ruchonnet, Antoine Béguin, Olivier Braun

The paper explores the additional services that Full Size Frequency Converter, FSFC, solution can provide for the case of an existing pumped storage power plant of 2x210 MW, for which conversion from fixed speed to variable speed is investigated with a foc ...

2017

Thermal-hydraulic modeling of a novel HTS CICC for nuclear fusion applications

Pierluigi Bruzzone

A thermal-hydraulic model has been developed for the novel cable-in-conduit conductor (CICC) recently proposed by ENEA, which foresees the use of 2nd Generation REBCO-based Coated Conductor tapes stacked into twisted grooves slotted into an Al core. A cent ...

IEEE Institute of Electrical and Electronics Engineers2016

Thermal Response of Multi-Microchannel Evaporators During Flow Boiling of Refrigerants Under Transient Heat Loads With Flow Visualization

John Richard Thome, Navid Borhani, Houxue Huang

Multi-microchannel evaporators with flow boiling, used for cooling high heat flux devices, usually experience transient heat loads in practical applications. These transient processes may cause failure of devices due to a thermal excursion or poor local co ...

Asme2016

Surge Wave Propagation in a Common Tailrace Channel for Two Large Pumped-Storage Plants

Anton Schleiss, Giovanni De Cesare, Martin Peter Bieri, Stéphane Christian Olivier Terrier

Sudden starting and stopping of turbines and pumps lead to highly unsteady flow in tailrace channels of hydropower plants (HPP). Submergence of Pelton turbines and air entrainment in pumps due to surge waves must be avoided by technical measures. The exist ...

Asce-Amer Soc Civil Engineers2014

Numerical investigation of the influence of leading and sequential bubbles on slug flow boiling within a microchannel

John Richard Thome, Mirco Magnini

Multiphase CFD simulations are presently employed to investigate the flow boiling of multiple sequential elongated bubbles in a horizontal microchannel. Most of the computational studies published so far explored the features of boiling flows within microc ...

Elsevier2013

Parametric study of water column separation in Francis pump-turbine draft tube

François Avellan, Christophe Nicolet, Sébastien Alligné

The paper presents the modelling, simulation and analysis of the transient behaviour of a 340 MW pump-turbine in case of emergency shutdown in generation mode with particular attention to the possible draft tube water column separation. First, the model of ...

Soc Hydrotechnique France2012

Simulation of water column separation in Francis pump-turbine draft tube

François Avellan, Christophe Nicolet, Sébastien Alligné

The paper presents the modelling, simulation and analysis of the transient behaviour of a 340 MW pump-turbine in case of emergency shutdown in turbine mode with focus on possible draft tube water column separation. The model of a pumped storage power plant ...

International Association For Hydraulic Research2012

Monitoring of Steel Lined Pressure Shafts Considering Water-Hammer Wave Signals and Fluid-Structure Interaction

Fadi Hachem

In the past, the safety margin for dynamic water pressure loads in steel-lined pressure tunnels and shafts was considered as acceptable by using conventional design safety factors. Due to high peak energy demands, existing plants are operating nowadays und ...

EPFL2011

Forced and Self Oscillations of Hydraulic Systems Induced by Cavitation Vortex Rope of Francis Turbines

Sébastien Alligné

With economical energy market strategies based on instantaneous pricings of electricity as function of the demand or the predictions, operators harness more hydroelectric facilities to off-design operating points to cover the variations of the electricity ...

EPFL2011

Constructal tree-shaped microchannel networks for maximizing the saturated critical heat flux

John Richard Thome, Rémi Revellin

A constructaltree-shaped microchannel network for maximizing the saturated critical heat flux in a disc-shaped planar body has been investigated. n(0) radial channels touch the center and n(p) channels touch the periphery. Designs with no pairing level (n( ...

Elsevier2009

Overload Surge Event in a Pumped-Storage Power Plant

François Avellan, Christophe Nicolet

At full load, pump-turbines operating in generating mode may experience a cylindrical cavitation vortex rope caused by the swirling flow in the draft tube cone. Under certain conditions, this vortex rope initiates both pressure and power oscillations. The ...

International Association For Hydraulic Research2006

Détection vibratoire de l'érosion de cavitation des turbines Francis

Cavitation erosion of Francis turbines continues to impose costly repairs and loss of revenues. This erosion is primarily caused by leading edge cavitation. A revue of the literature reveals the non-existence of an absolutely validated detection technique ...

EPFL2000