Numerical Simulation Of Ventilated Supercavitation Flow Of Underwater Vehicle

The underwater vehicle is subject to great resistance in the process of traveling,and the speed is limited.The supercavitation covering most of the wall surface of the vehicle is formed by artificial ventilation,which can greatly reduce the resistance of the vehicle and thus improve the traveling speed of the vehicle.In this paper,the MIXTURE multiphase flow model was used to simulate the ventilated supercavitation flow formed by a typical flat-head chamfer cavitator.The main research contents are as follows:First,the natural cavitation flow of the hemispherical head model was simulated and compared with the experimental results to verify the accuracy of the Zwart-Gerber-Belamri cavitation model.Different turbulence models were used to simulate the ventilated supercavitation flow of flat-head cavitator,and compared with the semi-empirical formula to verify its accuracy.The most suitable RNG k-ε model was selected for subsequent simulation.Then the ventilated supercavitation flow of a vehicle with a typical flat chamfer was simulated,researching the evolution process of the ventilated supercavitation and the development and velocity distribution of the cavitation at the characteristic positions near the shoulders and tail of the vehicle.The development of the boundary of the cavitation and the change of the pressure and velocity near the wall surface of the vehicle were also studied.Meanwhile the resistance characteristics of the vehicle were analyzed.The effects of different vent flow rate,inlet velocity,vent direction and different head cavitation models on the vent supercavitation flow and vehicle resistance were compared and analyzed.The simulation results are as follows: the insufficient ventilation flow is difficult to form a complete and stable ventilated supercavitation wrapped vehicle.With the increase of the ventilation flow,the supercavitation profile increases,and the increase range was very small after reaching the second critical value,and the resistance changes were very small.With the increase of incoming flow velocity,the supercavitation profile decreases and the drag increased significantly.With the increase of ventilation direction,the supercavitation profile increased,the resistance increased,and after the ventilation Angle reaches 45°,the boundary of supercavitation became unstable.The cavitation with hemispherical head is not conducive to the formation of stable ventilation supercavitation,and the cavitation with conical head is better than that with flat head.Finally,the 2d and 3d ventilation flow of supercavitation were compared and analyzed.Three-dimensional supercavitation head outline were not completely conical axisymmetric.The maximum profile section and minimum profile section of the head were selected for comparison with the two-dimensional ones,and the overall difference was similar.Meanwhile,the velocity distribution trend near the wall surface of the vehicle was consistent,and the velocity of the three-dimensional flow field in the main part of the vehicle was smaller.