Concept

Water hammer

Related publications (10)

Gyroid porous inserts as a novel flow control to mitigate tip vortex cavitation

Tip vortices generated at the tip of lifting surfaces pose significant challenges in fluid dynamics, causing induced drag, noise, and cavitation erosion risk across aerospace and hydraulic applications. Among the various mitigation strategies, porous tips have been explored with mixed results, showing limited effectiveness in diffusing concentrated vorticity. In this study, we introduce a gyroid-based porous tip as a novel passive flow control device for tip vortex mitigation. A gyroid is a triply periodic

Springer Science and Business Media LLC2026

Steadily moving semi-infinite fracture in plane poroelasticity

We present a boundary integral formulation for steadily propagating semi-infinite plane strain tensile and shear fractures in poroelastic media. By combining fundamental solutions of plane strain poroelasticity for an instantaneous fluid source and instantaneous edge dislocations (normal and slip modes) with temporal and spatial superposition principles, we derive boundary integral equations for steadily moving fractures under the adopted hydraulic boundary conditions. These equations relate the tractions (

Elsevier2026

Dynamic Characterization of Transient Cavitation in a Kaplan Turbine Model during Large Grid Frequency Disturbances

Tip leakage vortices are known to plague Kaplan turbines resulting in flow instabilities, noise, and cavitation erosion. This study investigates the tip leakage vortex cavitation (TLVC) experimentally on an emulated grid-coupled lab-scale Kaplan turbine during transient power stepping operations under two cavitation numbers, namely

(\sigma = 1.0)

and

(\sigma = 0.6)

. The two turbine power-stepping modes consist of runner rotational speed and blade angle variations. This is to characterize the behavio

Research Square Platform LLC2025

Impedance pumping as a non-invasive treatment for underactive bladder? An ex-vivo proof-of-concept-study in porcine bladders

Yves Perriard, Yoan René Cyrille Civet, Francesco Clavica

In patients suffering from underactive bladder (UAB), the contraction of the detrusor muscle has insufficient strength or duration to ensure efficient bladder emptying. Although catheterisation is currently the most effective method to empty the bladder, i ...

2019

Unsteady hydraulic simulation of the cavitating part load vortex rope in Francis turbines

François Avellan, Arthur Tristan Favrel

For Francis turbines at part load operation a helical vortex rope is formed due to the swirling nature of the flow exiting the runner. This vortex creates pressure fluctuations which can lead to power swings, and the unsteady loading can lead to fatigue da ...

2017

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

François Avellan, Christophe Nicolet, Nicolas Ruchonnet, Antoine Béguin

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

Surge tank throttles for safe and flexible operation of storage plants

Anton Schleiss, Giovanni De Cesare

Throttle surge tanks are a part of high head powerplants. The main consequence of a throttle placement is to introduce head losses by accelerating the flow. They make it possible to manage extreme water levels during mass oscillations while increasing water surge, e.g. water hammer, in the headrace tunnel. This phenomenon happens every time the flow discharge is changed in the waterway. Either throttle is placed during construction to reduce costs or its placement is needed following a refurbishment to adap

2016

Numerical and experimental evidence of the inter-blade cavitation vortex development at deep part load operation of a Francis turbine

François Avellan, Arthur Tristan Favrel, Christian Landry, Andres Müller, Keita Yamamoto

Francis turbines are subject to various types of the cavitation flow depending on the operating condition s. In order to compensate for the stochastic nature of renewable energy sources, it is more and more required to extend the operating range of the gen ...

International Association For Hydraulic Research2016

Computational Study of Saturated Flow Boiling Within a Microchannel in the Slug Flow Regime

John Richard Thome

This paper presents a fundamental study of the flow dynamics and heat transfer induced by a slug flow under saturated flow boiling in a circular microchannel. Numerical simulations are carried out by utilizing the commercial CFD solver ANSYS FLUENT v. 14.5, with its built-in volume of fluid (VOF) method to advect the interface, which was improved here by implementing self-developed functions to model the phase change and the surface tension force. A continuous stream of bubbles is generated (by additional u

American Society of Mechanical Engineers2015

Experimental investigation of the local wave speed in a draft tube with cavitation vortex rope

François Avellan, Christophe Nicolet, Arthur Tristan Favrel, Christian Landry, Andres Müller, Keita Yamamoto

Hydraulic machines operating in a wider range are subjected to cavitation developments inducing undesirable pressure pulsations which could lead to potential instability of the power plant. The occurrence of pulsating cavitation volumes in the runner and t ...

IOP Publishing Ltd2014

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