Experimental investigation of a cavitating backward-facing step flow

27th IAHR Symposium on Hydraulic Machinery and Systems

Maurice, G.^1,2 ; Djeridi, H.^1 ; Barre, S.^1

Laboratoire LEGI, Domaine Universitaire, BP53, Grenoble CEDEX, 9

38041, France^1

Centre National d'Études Spatiales, France, France^2

关键词: Backward-facing step flows;    Experimental investigations;    High Reynolds number;    Laser Doppler Velocimetry;    Liquid velocities;    Physical analysis;    Vortex structures;    Vortical structures;   

Others  :  https://iopscience.iop.org/article/10.1088/1755-1315/22/5/052008/pdf
DOI  :  10.1088/1755-1315/22/5/052008

来源: IOP

【 摘 要 】

The present study is the first part of global experimental work which is intended to produce a refined database of liquid and vapor phases and to improve CFD modeling of turbulent cavitating flows which can occur in rocket engine turbo-pump inducers. The purpose of the present experimental study is to get a better understanding of the dynamics of the liquid phase in a cavitating backward facing step flow and provide a refined database for the physical analysis of interaction between turbulence and cavitation. The backward facing step flow provides us a well-known test case to compare vortex dynamics and a realistic industrial configuration such as backflow in turbo machinery. Experiments were conducted in the hydrodynamic tunnel of CREMHyG at Grenoble,which was especially designed to study cavitating shear flows at high Reynolds numbers. To highlight the liquid phase topology and dynamics such as large vortex structures, free shear layer instability, reattachment wall interaction and reverse flow, the flow is characterized by Laser Induced Fluoresence Particles Image Velocimetry (PIV-LIF) measurements techniques and by Laser Doppler Velocimetry (LDV) techniques using spectral analysis to characterize the vortex shedding dynamics. The liquid phase was analyzed at different cavitation levels corresponding to 1% to 45% of void ratio range inside the shear layer, recirculation area and reattachment zone. The mean and fluctuating liquid velocities are clearly modified by the vapor phase and the scale of the vortical structures tends to be smaller inducing a destructuration of turbulence by cavitation.