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Concept

Pressure head

Publications associées (26)

The influence of the gas on the dynamics of cavitation bubbles

Davide Bernardo Preso

Cavitation bubbles, extensively investigated in fluid mechanics, present enduring challenges in hydraulic machinery, while holding considerable potential for practical applications in biomedicine and sonochemistry. Despite more than a century of research, ...

EPFL2023

Bottom-Pressure Development Due to an Abrupt Slope Reduction at Stepped Spillways

Anton Schleiss, Michael Pfister, José Pedro Gamito de Saldanha Calado Matos, Mohammad Javad Ostad Mirza

Fluctuating bottom-pressures on stepped chutes are relevant for the spillway design. An abrupt slope reduction causes a local alteration of the bottom-pressure development. Little information is available regarding the air–water flow properties near an abr ...

2022

Plunging Circular Jets: Experimental Characterization of Dynamic Pressures Near the Stagnation Zone

Giovanni De Cesare, Pedro Filipe De Almeida Manso, Gregoire Aurelien Marie Jamet

Spillways are a requirement for dams’ safety, mainly preventing overtopping during floods. A common spillway solution involves plunging jets, which dissipate a considerable flow energy in the plunge pool. Energy dissipation has to occur in a controlled man ...

2022

Adiabatic two-phase pressure drop of carbon dioxide in different channel orientations

Jürg Alexander Schiffmann, Rémi Revellin, David Schmid

Adiabatic pressure drop measurements of two-phase Carbon Dioxide (CO2) have been carried out in horizontal, vertical upward and downward direction with a dedicated test facility at the European Organization for Nuclear Research (CERN). A database of more t ...

2022

Experimental and Numerical Study on Scour-Protection Methods in a Stilling Basin: Case Study of Chancy-Pougny Dam

Anton Schleiss, Giovanni De Cesare, Erik Bollaert, Sabine Chamoun, Davide Wüthrich

Chancy-Pougny is a run-of-river dam on the Swiss–French border constructed in the early 1920s. Since its commissioning, the operation of the four spillway gates has been responsible for a progressive erosion of the stilling basin. The future scour potentia ...

2021

Design and fabrication of a vigorous "cavitation-on-a-chip" device with a multiple microchannel configuration

Luis Guillermo Villanueva Torrijo, Mohammad Jafarpour

Hydrodynamic cavitation is one of the major phase change phenomena and occurs with a sudden decrease in the local static pressure within a fluid. With the emergence of microelectromechanical systems (MEMS), high-speed microfluidic devices have attracted co ...

SPRINGERNATURE2021

Temporal and spatial evolution of cavitating bubbles and coherent structures in a confined submerged jet shear layer

Sebastián Camilo Leguizamón Sarmiento

Purpose The study aims to display the bubbles' evolution in the shear layer and their relationship with the pressure fluctuations. Furthermore, the coherent structures of the first six modes are extracted, in order to provide insight into their temporal an ...

EMERALD GROUP PUBLISHING LTD2021

An experimental study on the upper part-load elliptical vortex instability in a Francis turbine

François Avellan, Elena Vagnoni, Andres Müller, Arthur Tristan Favrel, Ali Amini

This paper presents preliminary results of an experimental study on the occurrence and development of the upper part-load instability in a reduced-scale Francis turbine. The study includes draft tube pressure measurements, high-speed flow visualization, an ...

IOP Publishing2021

Physical Mechanism and Flow Control of Tip Vortex Cavitation

Ali Amini

Occurrence of cavitation in hydraulic machines is a challenging issue because it is often accompanied with loss of efficiency, noise emissions, vibrations, and erosion damages. Tip vortices, in particular, are an ideal site for the development of cavitatio ...

EPFL2020

Head motion measurement and correction using FID navigators

Tobias Kober, Maryna Volodimirivna Waszak

Purpose: To develop a novel framework for rapid, intrinsic head motion measurement in MRI using FID navigators (FIDnavs) from a multichannel head coil array. ...

WILEY2019

Rotating air-water ring in the vaneless gap of a pump-turbine operating in condenser mode

François Avellan, Elena Vagnoni, Loïc Andolfatto

The rotating air-water ring, featuring a bubbly flow, in the vaneless gap of a reduced scale physical model of a pump-turbine operating in dewatered condition is investigated. High speed visualizations are performed together with pressure fluctuation measu ...

2018

A new bioinspired method for pressure and flow sensing based on the underwater air-retaining surface of the backswimmer Notonecta

Goran Lovric

In technical systems, static pressure and pressure changes are usually measured with piezoelectric materials or solid membranes. In this paper, we suggest a new biomimetic principle based on thin air layers that can be used to measure underwater pressure c ...

2018

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

Computational Fluid Dynamics-Based Pump Redesign to Improve Efficiency and Decrease Unsteady Radial Forces

Linlin Cao, Ning Chu

In this study, a double volute centrifugal pump with relative low efficiency and high vibration is redesigned to improve the efficiency and reduce the unsteady radial forces with the aid of unsteady computational fluid dynamics (CFD) analysis. The concept ...

Asme2017

Experimental study on the influence of abrupt slope changes on flow characteristics over stepped spillways

Mohammad Javad Ostad Mirza

Application of stepped spillways increases the energy dissipation rate along the spillway and may reduce the dimensions of the terminal energy dissipation structure. This pronounced energy dissipation makes stepped chutes attractive under various condition ...

EPFL2016

Dynamics of the cavitation precessing vortex rope for Francis turbines at part load operating conditions

Arthur Tristan Favrel

The massive penetration of the existing electrical grid by renewable energy sources requires a continuous extension of the operating range of hydroelectric powerplants, which can lead to cavitation flow instabilities inducing undesirable mechanical vibrati ...

EPFL2016

Francis turbine draft tube modelling for prediction of pressure fluctuations on prototype

François Avellan, Arthur Tristan Favrel, Christian Landry, Sébastien Alligné

The prediction of pressure fluctuations amplitudes on Francis turbine prototype is a challenge for hydro-equipment industry since it is subjected to guarantees to ensure smooth and reliable operation of the hydro units. The European FP7 research project Hy ...

Iop Publishing Ltd2015

Air entrainment and pressure development in skimming flow on an abrupt slope change on stepped spillways

Anton Schleiss, Michael Pfister, José Pedro Gamito de Saldanha Calado Matos, Mohammad Javad Ostad Mirza

Numerous stepped spillways were built to date, namely on RCC gravity dams or on valley flanks besides embankment or rockfill dams, while some others are currently under design or construction. In some cases, slope changes may be required on stepped chutes, ...

2015

Analysis of the part load helical vortex rope of a Francis turbine using on-board sensors

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

The cavitation helical vortex rope arising at Francis turbine partial load induces pressure fluctuations at the rope precession frequency, which can be decomposed into two components; the convective one and the synchronous one. The latter acts as an excita ...

Iop Publishing Ltd2015

Pressure measurements and high speed visualizations of the cavitation phenomena at deep part load condition in a Francis turbine

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

In a hydraulic power plant, it is essential to provide a reliable, sustainable and flexible energy supply. In recent years, in order to cover the variations of the renewable electricity production, hydraulic power plants are demanded to operate with more e ...

IOP Publishing2014