Influence of Rotor Dimple Geometry on Cavitation Characteristics of Rotational Cavitation Generator

Abstract

The current investigation is aimed to simulate the internal flows in a rotational cavitation generator with a rotor and a stator by using the RNG k-ε turbulence model and Zwart-Gerber-Belamri cavitation model. The design of the cavitation generator is that the rotor is provided with surface dimples. A detailed analysis of the pressure distribution, vapor volume fraction distribution and velocity distribution in cavitation generator with five different structures (5 different depth of rotor dimples h=25mm, 35mm, 45mm, 55mm, 65mm) under the same operation condition, is presented. The simulation results demonstrate that the characteristics of velocity and pressure area and cavitaion area are quite different based on the magnitude of the dimple depth of the rotor. It is showed that with the rotor dimple depth increase, cavitation area appears in the low pressures area at the bottom of the dimple and expands rapidly inside dimple; near the top of the dimple, the pressure gradient becomes larger and larger and velocity gradient changes dramatically; which induces strong flow disturbance at the top of the dimple and on the surface of the rotor, the water vapor exchange effect is enhancing, and the cavitation effect is getting stronger and stronger. The cavitation effect of the rotational hydrodynamic cavitation generator can be enhanced by increasing the depth of the rotor dimple.