Unsteady Cavitation Analysis Using Phase Averaging and Conditional Approaches in a 2D Venturi Flow

Vincent Aeschlimann, Stéphane Barre, Henda Djeridi

LAMH, Université Laval, Quebec, Canada.
LEGI, UMR 5519, Grenoble, France.
LPO, UMR 6523, Brest, France.

DOI: 10.4236/ojfd.2013.33022                

Abstract

The present study refers to a cavitating Venturi type section geometry characterized by a convergent angle of 18° and a divergent angle of about 8° where the sheet cavity presents typical self-oscillation behavior with quasi-periodic vapor clouds shedding. This work is an extension of previous works concerning void ratio measurements and velocity fields using double optical probe and constitutes a complete analysis of the two-phase structure of unsteady cavitating flow. This paper provides a new method based on conditional and phase averaging technique with wall pressure signal to treat experimental data in order to evaluate more precisely time-averaged and rms values of the void ratio and instantaneous velocity fields. Conditional analysis shows a different behavior of the two-phase flow dynamics leading to highlight high void ratio events linked to the break-off cycle. Unsteady phase averaging of the optical probe signal gives the evolution of the void ratio at each studied location in the venturi and shows that the fluctuations close to the wall (where the re-entrant jet is predominant) are in phase with the upper part of the cavity instead of the thickness of the cavity which is unchanged.

Keywords

Unsteady Cavitation; Sheet Cavity; Optical Probes; Venturi-Type Flow; Turbo Pump

Conflicts of Interest

The authors declare no conflicts of interest.

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