关键词: 水陆两栖车辆, 泵车一体化, 水动力特性, 浅水效应, 计算流体力学

Abstract: The water jet propeller is the main force of amphibious vehicle when it navigates on the surface, and there are large differences between the vehicle body attitude and propeller inlet conditions at different navigation depths in the land-water interface zone, which significantly affects the propulsion performance. In order to study the interaction between amphibious vehicle and water jet propulsion under water depth conditions, this paper takes water jet propulsion amphibious vehicle as the research object, and adopts the finite volume method, SST turbulence model, VOF two-phase flow model and DFBI motion model to carry out numerical calculations on the hydrodynamic performance of amphibious vehicle and propulsion integration under different speeds of water jets and different water depths. The grid uncertainty analysis is completed, and the accuracy of the algorithm is verified by comparing the calculated values with the experimental results, and the motion law, flow field distribution characteristics and hydrodynamic performance of the pump-car-integrated amphibious vehicle under different navigation conditions are obtained. The results show that: in the deep water environment, the amphibious vehicle is in the drainage sailing state, the longitudinal inclination angle and the amount of lift and sink slowly increase with the increase in speed; the vehicle body attitude changes greatly in low-speed sailing, which affects the stability of the axial flow of the fluid in the propeller, and the separation of the inter-lobe flow is enhanced; the vehicle body sailing state is relatively stable with the propeller's flow rate and lift in the high-speed sailing. In the shallow water environment, the amphibious vehicle is in the subcritical state when sailing at low speeds, with a larger longitudinal inclination under the effect of pressure difference between the bow and the stern, and a larger amount of sinking, and the resistance of the vehicle body increases by 13.65% on average compared with the deep-water condition; the vehicle body enters into the supercritical state when sailing at high speeds, and the increase in the dynamic lift causes it to float rapidly, and the sailing speed is on a par with that of the deep-water condition, and the change in the attitude of the vehicle under this state is small, and the performance of the thrusters is improved. Stability is improved. Therefore, when the amphibious vehicle passes through the shallow water area, the output power of the propellers should be increased to avoid the increase of resistance and deterioration of propulsion performance caused by the shallow water effect under the low-speed navigation, and enter the supercritical state quickly to obtain better navigation performance.

Key words: amphibious vehicle, pump-vehicle-integration, hydrodynamic characteristics, shallow water effects, Computational Fluid Dynamics