| Underwater glider has the advantages of low energy consumption,long endurance,low noise and low cost,which is thus used in various ocean explorations.In addition,the complexity of the marine environment puts forward higher requirements for the motion performance of underwater glider.With the increasing demand for underwater glider in marine application,how to improve the prediction accuracy of underwater glider’s motion performance has become an urgent problem.The prediction accuracy of underwater glider’s motion performance depends on the accuracy of hydrodynamic coefficient.The accuracy of added mass,which is directly affects the prediction accuracy of dynamic model.In this paper,the Petrel-L underwater glider independently developed by Tianjin University is taken as the research object,the dynamics model in a six DOF space is established,and the numerical simulation method of added mass of underwater glider based on computational fluid dynamics(CFD)is studied,which meets the requirement for fast and accurate solution of added mass.The research contents and achievements of this paper are as follows:Firstly,the six DOF space dynamic model of the Petrel-L underwater glider is established.In this model,the underwater glider is regarded as a variable mass body with a fixed profile.At the same time,the model considers the influence of sea water density on the motion of underwater glider,which improves the prediction accuracy of the dynamic model.Secondly,a method of solving the added mass of underwater glider based on the low speed,small amplitude periodic motion CFD numerical simulation is proposed.The commercial CFD software STAR-CCM+ is used to calculate the added mass of the Petrel-L.Compared with the Hess-Smith panel method based on the potential flow theory,the relative error of the added mass is less than 5%.Compared with the pool test results of the underwater glider,the relative errors of the added mass except those perpendicular to the direction of the wing of the underwater glider are within 6%,which is better than the CFD numerical simulation of the plane motion mechanism test.Finally,the dynamic model of underwater glider in longitudinal plane is simplifyed,and the simulation results with different added masses are compared with the sea trial data.The results show that the motion of underwater glider is consistent with the sea trail data under the accurate added mass.At the same time,this paper discusses the principle of spiral motion of underwater glider,and compares the characteristics of spiral motion of underwater glider with different added mass. |
