Numerical simulation of oblique water-exit process of trans-media aerial underwater vehicle

Tan Junyi，Hu Junhua*，Chen Guoming，Yang Jian，Ge Yang School of Aeronautics Engineering，Air Force Engineering University，Xi'an 710038，China Abstract：［Objectives］ The oblique water-exit process of a Trans-Media Aerial Underwater Vehicle （TMAUV）is highly non-linear，unsteady and drastic in flow field. Based on the underwater configuration of a TMAUV，the two-dimensional numerical simulation of the process is carried out by using CFD fluid simulation software under the typical conditions.［Methods］The flow field variation characteristics and the load distribution of the vehicle at different stages of the water-exit process were analyzed，and the distribution of flow velocity field at two typical positions and characteristics of hydrodynamic forces acting on the vehicle in case of water-exit at different pitch and attack angles was compared. ［Results］ The simulation results show that the flow field and load on both sides of the vehicle will change dramatically when it crosses the water-air interface obliquely. The larger the pitch angle is，the smaller the range of the part of flow field under water will be affected，and the larger the impact on the part of flow field crossing and above the water will be. Compared with the case of water-exit at zero angle of attack，the oblique water-exit of the vehicle at an angle of attack will lead to high frequency and large-scale reverse oscillation of the hydrodynamic force acting on the surface and affect the stability of the vehicle when it exits water. ［Conclusions］ The results in this paper can provide ideas and theoretical reference for the study of water-exit of submarine-launched missiles，navigation of ships，cross-medium of submarines and other topics. Key words：Trans-Media Aerial Underwater Vehicle（TMAUV）；oblique water-exit process；fluid simu⁃ lation；flow field distribution；load characteristics