Launch characteristics of autonomous underwater vehicle into water and suction characteristics of tail propeller in near free liquid position

Airborne autonomous underwater vehicles (AUVs) are transported over a specific sea area using a consignment device and enter the water for operations by airdrop. During entry into the water, a series of pressure pulsations are created on the surface of the airframe due to the impact of the airframe against the current, these pressure pulsations can propagate to the components loaded inside the AUV and cause the device to malfunction. On the other hand, when the AUV is operating near the surface, the suction effect of the tail propeller can cause a significant reduction in propulsion efficiency. In this paper, a series of numerical experiments are carried out to investigate the launch characteristics of the AUV into the water and the suction characteristics of the tail propeller. The numerical prediction of the AUV entry process at different angles and speeds is carried out using the overset grid method, and the response curves of the AUV entry aerodynamic characteristics with different launch parameters are obtained. The evolving mechanism of the vacuole of the AUV under 30 degrees water entry conditions is discussed in detail. The suction characteristics of the propeller at different sinking depth positions are calculated using the slip grid method. The calculation results show that the propulsion efficiency of the propeller is related to both the inlet speed coefficient and the different sinking depths. The above numerical models are built using OpenFOAM as the basic framework.