Computational Study of Unsteady Cavitating Vortex Flow in Axisymmetric Submerged Water Jet

Abstract

Unsteady cavitating and non-cavitating flows of high-speed submerged water jet have been investigated numerically by applying an approach based on the two-phase cavitation model to clarify the behavior of cavitating vortex flow in the near field of jet. The cavitation intensity is calculated by VOF method accounting for expanding and contracting of cavitation bubbles with the barotropic relation and the unsteady flow is calculated by RANS method employing the RNG k-ε turbulence model under the assumption of locally homogeneous two-phase flow. Computations are focused on the behavior of starting jet, and the validity is confirmed by comparing with experimental data. The result shows that a starting vortex ring is generated around the jet periphery, and develops with the vortex formation time. The relative standoff distance of ring-like cavity of cavitation bubbles generated in the starting vortex increases with the dimensionless vortex formation time similarly under different injection velocities.