TITLE:
Unsteady Cavitation Analysis Using Phase Averaging and Conditional Approaches in a 2D Venturi Flow
AUTHORS:
Vincent Aeschlimann, Stéphane Barre, Henda Djeridi
KEYWORDS:
Unsteady Cavitation; Sheet Cavity; Optical Probes; Venturi-Type Flow; Turbo Pump
JOURNAL NAME:
Open Journal of Fluid Dynamics,
Vol.3 No.3,
September
18,
2013
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.