Research On Maneuverability Of Submersible Amphibious Vehicle

Traditional amphibious vehicles can only sail on land and water,increasing the submersible performance of amphibious vehicles,avoiding wind and waves at sea,effectively reducing navigational resistance,increasing the concealment of vehicles,and significantly improving reconnaissance capabilities and operation time.Therefore,the maneuverability of amphibious vehicles under water has important research significance and application value This article refers to the American amphibious chariot AAAV,and establishes a submersible amphibious vehicle scheme with a symmetrical wedge-shaped body as the main body,a waterjet as the propulsion device,a fuel cell as its power device,and a vector nozzle as its control device.The maneuverability of underwater navigation under this scheme is studied.Firstly,the resistance performance of submersible amphibious vehicles was researched by the viscous flow CFD method.The calculation strategy of the viscous flow CFD method to calculate the navigation resistance of the amphibious vehicle under underwater conditions was discussed and verified.The head and tail profile changes were analyzed based on the calculation strategy.The influence on the resistance performance is based on the optimal design of the body shape of the optimal resistance body,the navigation resistance of the amphibious vehicle under different operating conditions at different speeds is calculated,and the analysis of the potential depth on the resistance performance and the wake caused by the free surface wave Impact of stealth performanceSubsequently,the water-jet propulsion performance of the amphibious vehicle was studied,and the flow velocity at the nozzle exit was numerically simulated according to the momentum theorem.The influence of different nozzle shapes on the velocity of the ejected fluid was discussed.The effect of the injection velocity of the deviceAccording to the shape characteristics of amphibious vehicles,the maneuverability of amphibious vehicles under underwater conditions is further studied.Based on the viscous flow method,numerical simulations of the underwater wedge test and plane motion mechanism tests of the symmetrical wedge-shaped vehicle body were carried out.The feasibility of the method was verified by numerical simulation and theoretical calculation of the ellipsoid model.By this method,the hydrodynamic changes of the vehicle body at different drift angles and speeds are obtained,and the viscous hydrodynamic derivatives are obtained.For the hydrodynamic derivatives that cannot be obtained by this method,refer to the solution of the submarine nonlinear hydrodynamic derivatives.Based on the maneuverability equation,the rotation of the car body with different nozzle arrangements is simulated.Compared with the numerical simulation of the car body rotation motion,the accuracy is verified and the optimal arrangement of the nozzle arrangement is analyzed.In order to further understand the stability of amphibious vehicles when underwater,the roll and pitch angles were stabilized within a certain range.By establishing a total of four ballast tanks in front,rear,left,and right to adjust the pitch and roll angles,the relationship between the change of the tilt angle and the time of the car body when there is no speed under water is discussed.The simulation analysis shows that it is possible to Maintain good stability.