Research Of Supercavitation Flows And Underwater Vehicle Trajectory Characteristics

Supercavitating technology is a kind of underwater drag reduction technology which canreduce the friction drag through forming a cavity and enwrapping the vehicle with the actionof cavitator、 low pressure vaporization and artificial ventilation. The studied ofsupercavitating flow numerical simulation with considering the phase transition model,turbulence and compressibility effects and the trajectory characteristics of supercavitationvehicle were carried out.The cavitation source term was studied under the condition of with and withoutconsidering the compressibility of mixed multiphase. The nature and ventilated cavitationsource term which dimension is consistent with the transport equation of vapor phase wereestablished based on the R-P equation under the condition of with and without considering thecompressibility of mixed multiphase. The steady cavitation flows, the cavity developmentcharacteristics of unsteady cavitation flows and the3D effects of cavitation flows werestudied and compared with experimental data of references. The validity of the formulas andalgorithms were verified based on the simulation results.The cavity shape and cavitation drag characteristics of sub and supersonic cavitationflow in water were studied based on the slender body theory. The results shows that the valueof cavity slenderness ratio and cavitation drag is increases and decreases with the Machnumber increases in subsonic and supersonic region respectively and the influence of Machnumber to the cavity slenderness ratio is smaller than the cavitation number’s. The subsonicwith considering the compressibility effect of water and vapor were numerical simulated inwater. The results shows that the value of pressure and water density are increased evidentlyin bow region of the vehicle head in the subsonic supercavitation flows in water with theMach number increases.The gas balance equations in cavity、equations of cavity section expression、positionrelationship between the vehicle and cavity、hydrodynamic calculation methods and vehicledynamic equations were considered. The trajectory characteristics of vehicle high-speed waterentry with supercavitation in vehicle vertical plane were studied. The trajectory characteristicsof vehicle with and without control scheme in ventilation accelerated motion stage（VAMS）and cruise stage were studied. The vehicle trajectory characteristics of horizontalmovement and6-DOF movement were studied. The results show that the water entry cavityunsteady phenomena will be arosed with considering the gas elasticity, and the wall-wavephenomena will be appeared; the vehicle mass centre remains in the fixed deep positionwithin a small deviation with considering the control scheme; the vehicle gesture in horizontalplane are damped oscillation with small amplitude and big frequency with considering thegravity and V-shape supercavitating hydrofoil stabilization schemes.