Coupling Effect of Vehicle Body and Waterjet Propulsion on Hydrodynamic Performance of Amphibious Vehicle
Different from traditional surface ships,amphibious vehicles involve two working modes:land walking and water navigation,so that the interaction between vehicle body and waterjet propulsion is essential to explore and understand.Based on the computational fluid dynamics(CFD)method,a coupling numerical simulation method of amphibious vehicle and waterjet propulsion is established to simulate the navigation characteristics of amphibious vehicles under constraint conditions.The influence of inlet duct and impeller-guide vanes on the stability and resistance of the vehicle body is studied.By comparing the numerical results with the model towing test,the validity of CFD method in hydrodynamic performance prediction of amphibious vehicles is verified.The results show that inlet duct and impeller-guide vanes have significant impact on the hydrodynamic performance of amphibious vehicles.Due to the influence of the inlet duct and impeller,at speed Fr=0.953 and pitch angle θ=10°,the difference between the calculated results and those of the bare vehicle body is 2.03％and 4.77％,respectively.The uniformity of inlet flow is affected by the blunt body structure of amphibious vehicles,and the difference between the surrounding flow field and the inner flow inside increases with the increase of speed and trim.The vortex in the flow separation zone is obviously offset due to the impeller operation,which affects the outlet flow field.
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