Numerical simulation research on hydrodynamic characteristics of HAG-UUV hung under aircraft wing

A series of numerical simulations were carried out to investigate hydrodynamic characteristics of the high-altitude glider underwater unmanned vehicle (HAG-UUV) hung under the aircraft wing. In the horizontal plane and the vertical plane, the flow disturbance acting on the HAG-UUV was analyzed. Considering the coupling of the HAG-UUV and the wing, numerical simulations were completed using Ansys CFX. The conditions of different distances between the center of buoyancy of the HAG-UUV and the aircraft wing from 540 mm to 940 mm, different attack angles from -5° to 20° and different sideslip angles from -15° to 15° were investigated. Then, the curves of the fluid forces and torques were drawn. Results have shown that when the distance between the center of buoyancy and the wing is smaller than 760 mm, wall effect is significant, and the fluid forces acting on the HAG-UUV in the vertical direction rapidly increases. The attack angle greatly enhances the hydrodynamics of the HAG-UUV. When the sideslip angle changes from -15° to 15°, the hydrodynamics acting on the HAG-UUV are not asymmetrical about 0° sideslip angle. When the sideslip angle is 0°, the HAG-UUV is still disturbed by the lateral force and yaw moment. The reason for this phenomenon lies in the sweepback wing, resulting in lateral induced velocity of the flow field.