A practical mixture flow method is proposed for numerical simulation of high-speed cavitating flow by coupling a bubble cavitation model and a compressible two-phase mixture flow computation. Two-phase fluid media are treated as a mixture composed of a liquid and spherical gas bubbles dispersing in the liquid phase uniformly. Mean flow of the two-phase mixture is calculated by neglecting the slip between bubbles and the liquid phase under the assumption of locally homogeneous medium. Navier-Stokes equations for compressible fluids are used to describe the unsteady flow field of bubble-liquid mixture considering the compressibility of cavitating liquid caused by bubble expansion and contraction, and the RNG k-ε model is adopted for modeling of flow turbulence. The intensity of cavitation in a local field is evaluated by the volume fraction of gas phase varying with the mean flow. Submerged water jet flows in a Venturi nozzle are treated under different cavitation numbers. The result demonstrates that pressure decreases from the inlet to the throat corresponding to the flow convergence and cavitation occurs in the low-pressure region between the wall and the shear layer. Under the influence of cavitation the discharge coefficient decreases to about 60% when σ = 0.1 compared to the case of no-cavitating flow.
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