CFD Analysis of High-speed Cavitating Water Jet and Hydraulic Design of Jet Nozzle

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A mixture-flow bubble-cavitation model is proposed for unsteady cavitating flow computation by coupling a Two-Fluid Three-Pressure bubble dynamics model and a compressible two-phase flow computation. The fluid media of cavitating flow is treated as a mixture of liquid and spherical gas bubbles, those are supposed to disperse in the liquid phase uniformly. The average bubble radius in a local flow field is calculated by Rayleigh-Plesset equation and cavitation is evaluated by the volume fraction of gas included in bubbles. State equations of liquid and gas phases are employed to define the compressibility of two-phase mixture and a set of mean flow governing equations is developed by phase-averaging. The method is applied to treat flows in an orifice nozzle as well as a venture nozzle and the reliability of computation results is confirmed.