In ventilated cavitating flow structure, two parameters are very important, Fr number and gas entrainment coefficient .The objective of this paper is to investigate the ventilated cavitating flow structure by numerical methods and verify with experimental results. The numerical simulation is performed by ANSYS-FLUENT and homogenous mixture model with a free slip velocity and DES turbulence model, and the gravity effect is considered. The results show when the gas entrainment coefficient Qv is constant, two typical mechanisms of the gas leakage exist at different Fr numbers, namely toroidal vortex mode and two hollow tube vortex mode .With the increasing of Fr, the cavity would transfer from the two hollow tube vortices to the toroidal vortices. Moreover, when the Fr number keeps constant, the enlargement of the cavity causes the gravitational effect to be more significant for the case of larger value of Qv. DES turbulence model is combined from two model, SST k – ω and LES model and is suitable for simulating of two hollow tube vortices mode

Keywords: Ventilated cavitating flow, Gas leakage behavior, Super cavitation

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