Numerical approach to reproduce instabilities of partial cavitation in a Venturi 8° geometry

28th IAHR symposium on Hydraulic Machinery and Systems

Charriere, Boris^1 ; Goncalves, Eric^2

Unviversity of Grenoble-Alpes, Laboratory LEGI, Grenoble, France^1

Department of Aeronautical Engineering ENSMA, Laboratory Pprime, Poitiers, France^2

关键词: Cavitation clouds;    Experimental and numerical studies;    Nonequilibrium state;    Numerical approaches;    Partial cavitations;    Periodic oscillation;    Reynolds-Averaged Navier-Stokes;    Transport equation;   

Others  :  https://iopscience.iop.org/article/10.1088/1755-1315/49/9/092001/pdf
DOI  :  10.1088/1755-1315/49/9/092001

来源: IOP

【 摘 要 】

Unsteady partial cavitation is mainly formed by an attached cavity which present periodic oscillations. Under certain conditions, the instabilities are characterized by the formation of vapour clouds, convected downstream the cavity and which collapse in higher pressure region. In order to gain a better understanding of the complex physics involved, many experimental and numerical studies have been carried out. These identified two main mechanisms responsible for the break-off cycles. The development of a liquid re-entrant jet is the most common type of instabilities, but more recently, the role of pressure waves created by the cloud collapses has been highlighted. This paper presents a one-fluid compressible Reynolds- Averaged NavierStokes (RANS) solver closed by two different equations of state (EOS) for the mixture. Based on experimental data, we investigate the ability for our simulations to reproduce the instablities of a self-sustained oscillating cavitation pocket. Two cavitation models are firstly compared. The importance of considering a non-equilibrium state for the vapour phase is also exhibited. To finish, the role played by the added transport equation to compute void ratio is emphasised. In case of partially cavitating flows with detached cavitation clouds, the reproduction of convective mechanisms is clearly improved.