Research On Hydrodynamic Performance Of A Underwater Vehicle And Its Ducted Thruster Using The Hybrid Technique For Combining Dynamic With Sliding Meshes

The CFD method and the hybrid technique for combining dynamic with sliding meshes are utilized to numerically simulate the main body resistance of an underwater vehicle and thrust of a ducted propeller when the vehicle is in a straight line motion, in which the ducted propeller acts as a major control mechanism for the vehicle. Then, the effect of main body trailing vortex caused by lateral currents on thrust characteristics of the ducted propeller is observed, the hydrodynamic interactions among the main body resistance, thrust from the ducted propeller and the lateral current are analyzed. The numerical method applied in this research has the advantages of simple mesh updating, no negative mesh volume emerging and little impact on computational errors in the regions intensive vortex flow taking place. Simulation results indicate that(1) there is a noticeable disturbance of lateral current on the flow fields of components of the vehicle;(2) a non-ignorable influence of the trailing vortex caused by lateral currents on the main body resistance and the thrust from the ducted propeller can be found, the alternating cyclic forces caused by the trailing vortex on the conjunction between the main body and the ducted propeller are the major factor affecting the characteristics of the resistance and the thrust, to maintain a good course stability and maneuverability to an underwater vehicle during operations become a great challenge to designers users of the vehicle because of these cyclic forces;(3) numerical forecast on the hydrodynamic performance of an underwater vehicle can be made objectively only on the condition that the main body of the vehicle and the ducted propeller are combined as an integrated assembly in mathematical model, and numerical simulation should be conducted with such an integrated assembly in a specific running environment.