Publication detail
Computational modelling of cavitation in simple geometries, but complex flows
RUDOLF, P. KOZÁK, J.
Czech title
Výpočtové modelování kavitace jv jednoduchých geometriích, ale komlexních prouděních
English title
Computational modelling of cavitation in simple geometries, but complex flows
Type
conference paper
Language
en
Original abstract
Cavitation occurs when local pressure in flowing liquid drops below saturated vapor pressure. If the resulting vapor bubbles are transported to regions of higher pressure then sudden condensation follows, which is accompanied by emission of pressure and acoustic waves. Above described process leads to cavitation erosion and consequently to shorter service time of the hydraulic machines. Cavitation can be modeled by current CFD tools with simplified cavitation models. Computational simulations revealed that proper capturing of the underlying one-phase flow field is crucial to obtain correct vorticity distribution. Clouds filled with vapor are born from regions of concentrated vorticity and shed downstream. Only advanced turbulence models (Reynolds Stress Model, Scale Adaptive Simulation) are able to predict vorticity field and development of the unsteady swirling flow. Increased vorticity generation in two-phase flows is caused by additional term in vorticity equation – baroclinic torque. Present paper dicusses relative magnitude of vorticity generation terms for cases of concentrated vortical structure and separated boundary layer over hydrofoil.
Czech abstract
Při poklesu tlaku v kapalině na úroveň tlaku nasycených par dochází ke vzniku kavitace (kavitačních bublin), které při dalším transportu do oblasti vyššího tlaku zpětně kondenzují. Tento jev je provázen šířením tlakových vln a akustickou emisí, důsledkem je kavitační eroze obtékaného povrchu. Kavitaci lze výpočtově modelovat prostředky CFD s vyižitím zjednodušených kavitačních modelů. Článek ukazuje, že pro korektní výpočet kavitujícího proudění je nutné určit správnou hodnotu vířivosti, ktereá je generována na rozhraní fází v důsledku tzv. baroklinického členu. Hodnota tohoto členu je dokumentována u dvou typů proudění: kavitující koncentrovaný vír, odtržené proudění na hydraulickém profilu.
English abstract
Cavitation occurs when local pressure in flowing liquid drops below saturated vapor pressure. If the resulting vapor bubbles are transported to regions of higher pressure then sudden condensation follows, which is accompanied by emission of pressure and acoustic waves. Above described process leads to cavitation erosion and consequently to shorter service time of the hydraulic machines. Cavitation can be modeled by current CFD tools with simplified cavitation models. Computational simulations revealed that proper capturing of the underlying one-phase flow field is crucial to obtain correct vorticity distribution. Clouds filled with vapor are born from regions of concentrated vorticity and shed downstream. Only advanced turbulence models (Reynolds Stress Model, Scale Adaptive Simulation) are able to predict vorticity field and development of the unsteady swirling flow. Increased vorticity generation in two-phase flows is caused by additional term in vorticity equation – baroclinic torque. Present paper dicusses relative magnitude of vorticity generation terms for cases of concentrated vortical structure and separated boundary layer over hydrofoil.
Keywords in Czech
kavitace, vířivost, baroklinický člen
Keywords in English
cavitation, vorticity, baroclinic torque
RIV year
2014
Released
03.11.2014
Publisher
FAV ZČU Plzeň
Location
Plzeň
ISBN
978-80-261-0429-2
Book
Computational mechanics 2014; book of extended abstracts
Pages from–to
1–2
Pages count
2
BIBTEX
@inproceedings{BUT111327,
author="Pavel {Rudolf} and Jiří {Kozák},
title="Computational modelling of cavitation in simple geometries, but complex flows",
booktitle="Computational mechanics 2014; book of extended abstracts",
year="2014",
month="November",
pages="1--2",
publisher="FAV ZČU Plzeň",
address="Plzeň",
isbn="978-80-261-0429-2"
}