Numerical Simulation Of The Front-mounted Engine Supercavitation Torpedo Flow Field

The underwater vehicle has higher resistance and lower speed.Using supercavitation technology can significantly increase the speed of the underwater vehicle.At present,there is little research on the front-mounted engine supercavitation torpedo at home and abroad.The integration of propulsion and drag reduction can be achieved by putting the engine forward.In this paper,the Mixture multiphase flow model is coupled with the “full cavitation” model to simulate the ventilated supercavitating flow field of the front-mounted engine torpedo and the flow field considering the secondary jet of the nozzle.And the influence of different factors on the flow field and the force on the body is analyzed.Firstly,the typical ventilated supercavitating flow of disc cavitator is simulated to verify the rationality of mathematical model and method.In addition,comparing the accuracy of different turbulence models and pressure-velocity coupling modes for the calculation of ventilated supercavitating flow,the RNGk-? model and PISO algorithm were finally selected.Those lay the foundation for the subsequent simulation.Secondly,the flow field of ventilated supercavitation torpedo without nozzle secondary jet is simulated,and the evolution process of cavity,the change of the thickness of cavity at the characteristic positions of the body,the change of pressure,gas density,temperature and gas Mach number in scarfed nozzle and on the surface of the body are analyzed.The resistance and thrust characteristics of the body are also analyzed.The effects of the ambient flow velocity,the total temperature of head ventilation,the mass flow rate of head ventilation,the oblique tangent angle of nozzle and the cavitator angle on the flow field and the force on the body are considered.From the analysis of the simulation results,the conclusions are obtained.Resistance of body increases with the increase of the ambient flow velocity.With the increase of the total temperature of the head ventilation,the pressure drag decreases,the friction drag increases and the thrust increases slightly.As the mass flow rate of head ventilation increases,the resistance decreases and the thrust increases,when the mass flow rate reaches a certain critical value,the thrust and resistance basically remain the same.The scarfed nozzle has an optimum oblique tangent angle,so that the thrust reaches the maximumvalue.With the increase of cavitator angle,the lift increases rapidly,while the resistance decreases.Finally,the ventilated supercavitating flow field with nozzle secondary jet is simulated,considering the influence of the diameter of secondary jet tube,the injection position and the injection angle of secondary jet on the flow field and the lateral force and thrust of the body.From the analysis of the simulation results,the conclusions are obtained.With the increase of the diameter of the secondary jet tube,the lateral force increases and the axial thrust decreases.The closer the injection position of the secondary jet is to the upstream of the nozzle,the greater the lateral force,the smaller the axial thrust.As the injection angle of the secondary jet increases,the lateral force increases and the axial thrust decreases.