INVESTIGATION OF TWO MECHANISMS GOVERNING CLOUD CAVITATION SHEDDING: EXPERIMENTAL STUDY AND NUMERICAL HIGHLIGHT

Cavitation is a phenomenon of classical interest which can be observed in various applications. It consists in a transition of phase due to a pressure drop under the saturation pressure of a liquid. The unsteady behavior of this phenomenon leads to generate some issues such as erosion, noise or vibrations: as a result the comprehension of the cavity dynamics remains of crucial importance. Unsteady cavitation has been investigated in numerous studies and a mechanism of re-entrant jet has been firstly identified as responsible of the cavity shedding process. Recently, a second shedding mechanism, induced by a shock wave propagation due to the condensation of vapor structures, has been experimentally highlighted with X-ray measurements [1]. The present paper focuses on the experimental detection, with a wavelet method, of these two shedding features on 2D image sequences recorded with a high-speed camera about a double transparent horizontal Venturi nozzle with 18 degrees/8 degrees convergent/divergent angles respectively. A compressible two-phase flow numerical 3D model is performed in complement in order to illustrate some phenomena hardly perceptible experimentally.