Numerical Simulation of Unsteady Cavitation in a Submerged Water Jet by Compressible Bubbly Mixture Flow Method

Focused on the unsteady behavior of high-speed water jets with intensive cavitation a numerical analysis is performed by applying a compressible mixture-flow bubble-cavitation model. The mean flow of two-phase mixture is calculated by URANS for compressible flow and the intensity of cavitation in a local field is evaluated by the volume fraction of gas phase varying with the expansion and contraction of bubbles. High-speed submerged water jet issuing from a sheathed nozzle is treated when σ=0.1 and Re = 4.5×10⁵. The distribution of cavitation clouds predicted approximately agrees with experiment data of visualization observation and the unsteady behavior of cavitation cloud shedding is captured acceptably. Computational results reveal that cavitation occurs at the entrance of nozzle throat and bubble clouds develop and flow downstream along the boundary layer. Developed bubble clouds split into small blocks and shed downstream periodically near the exit of sheath.