Abstract：Four turbulent models of RNG k-ε、Realizable k-ε、k-ω and SST k-ω were employed to simulate the internal flow field of low-pressure self-excited pulsed cavitation jet nozzle and then verified the well-posedness of the selected models. The simulation results of three-dimensional unsteady flow field inside the nozzle show that the RNG k-ε turbulence model can simulate the pulse flow of cavitation nozzle accurately and it is easy to converge. Grid independence and time step optimization are also presented that time step can be as minor as possible. The gravity factor is taken into account to carry out the evolution process of the interior flow in one cycle by using the dynamic variables of pressure, velocity, water vapor volume fraction and temperature during the cavitation inception, energy concentration and energy release. The occurrence mechanism of the low pressure and large flux self-excited pulsed cavitation jet and the flow field evolution characteristics are also illustrated. Comparing the numerical simulation with the experimental results, it is verified that the selected turbulence model is appropriate and the evolution of the flow in the chamber is reliable. Considering the influence of gravity, the simulation results in the nozzle more coincide more with the actual situation in the engineering practice.
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