Hydrodynamic performance of a water-air trans-media flying submersible vehicle.

Water-air trans-media flying submersible is a new type of unmanned vehicle with important engineering applications. This paper describes pool towing experiment and numerical calculation methods conducted to study the influence of the submersible's velocity on the free water-surface, the hydrodynamic characteristics, and the flow field structure. The working conditions researched in this paper include the water-surface navigation and underwater diving. The results show that the lift and drag of the submersible increase with velocity, but the trend and range are greatly affected by the water depth, especially those of the lift. The high-pressure area on the surface is mainly distributed in the bow and appendage structure inflow area, and the low-pressure area is distributed behind the high-pressure area and the back-flow area. The influence of the free water-surface causes the wake field to dissipate rapidly and become asymmetric when water-surface navigation. The free water-surface is a Kelvin wave system. The Kelvin angle decreases and the wavelength and amplitude increase with velocity. When navigating on the water-surface, the bow wave and tail wave form a double-row Kelvin wave. When diving underwater, a Bernoulli dome appears on the water-surface above the bow, and the surface forms a regular single-row Kelvin wave. • Hydrodynamic performance of a water–air trans-media flying submersible vehicle is studied. • The free water-surface evolution of the flying submersible vehicle at different velocities is analyzed. • The flow structure over the vehicle and the force of the vehicle are discussed. [ABSTRACT FROM AUTHOR]