Research On Hydrodynamic Analysis And Rapid Diving Motion Of Multi-Mode High-Speed Platform

In view of the security pressure faced by our country in the ocean direction in recent years,a new concept which named Multi-Mode High-Speed Platform(MMHSP)was proposed.The platform can make high speed advance and fast fire support on the surface of the water,contact the enemy covertly while submerging and perform tracking and reconnaissance tasks,and conduct "frog leap" type anti-submarine searching relying on its rapid diving ability.The platform scheme design was completed according to the technical performance characteristics,and the hydrodynamic performance of the initial scheme and the improved scheme on the surface of the water and underwater were studied based on the CFD method.Besides,according to the numerical simulation results of the rapid diving motion process of the platform,the effects of diving mode,speed and rudder angle on the diving motion were discussed,and obtained the motion laws.The main research contents are as follow:First of all,two standard ships DTMB 5415 and SUBOFF-2 were selected and then numerically simulated the hydrodynamic performance in the hydrostatic field on the surface of the water and underwater,and obtained some hydrodynamic coefficients.The reliability of the numerical calculation method in this paper was verified by comparing with the results of Taylor Tank.Besides,the initial scheme design was completed according to the performance characteristics,and the hydrodynamic performance on the surface of the water and underwater were numerically simulated based on the CFD method.The motion performances and characteristics of the resistance were analyzed and the flow field distribution around the platform was discussed in this paper.Based on the discussions above,some suggestions of the initial scheme were put forward and formed the improved scheme.Based on the numerical simulation results of the improved scheme,the hydrodynamic performance was analyzed,and the comprehensive comparative analysis of the two schemes above was made at the end.In addition,based on the kinematics and dynamics analysis of the motion of the platform in the vertical plane,the 3-DOF diving motion equation was obtained.Because the platform needs to manipulate the bow or stern rudder during the rapid diving progress,the hydrodynamic performance of the single rudder at different angles of attack were also studied based on CFD method,and obtained the variation laws of lift coefficient and drag coefficient,and accordingly obtained the maneuvering characteristics of the bow and stern rudder.At last,the mathematical models of the rapid diving system were established according to the diving mode of the platform.And the numerical simulations of the diving motion process based on the interaction of the single rudder and the ballast tank were completed by CFD method.The changes of the depth and the pitch angle of the platform during the diving progress were obtained,and then analyzed the effects of speed,rudder angle and other factors,and obtained the rapid diving laws of the platform.