Research on positive buoyancy underwater glider and its sailing efficiency

Abstract Underwater glider can achieve marine data through profile motion, which has become an important means of ocean observation. This paper proposes a positive buoyancy underwater glider, which retains the wings and internal moving mass of traditional glider, but has no variable buoyancy system. The glider maintains positive buoyancy during the profile motion and the diving process is realized by a thruster. The positive buoyancy glider can achieve a higher sailing efficiency when the zero angle of attack of the vehicle is achieved by setting a certain installation angle of the wings. In addition, since the positive buoyancy glider has no complicated variable buoyancy system and the oil-pumping process, and achieves profile motion by directly changing the attitude, it is more suitable for shallow-water survey and provides reference for the development of large-scale gliders. In this paper, energy consumption per meter is used as an indicator of sailing efficiency. The effects of glide angle, installation angle and net buoyancy on sailing efficiency are studied and the optimal installation angle is calculated. It is theoretically proved that the energy consumption per meter is equal in four glide modes of the positive buoyancy glider. When the glide angle of the traditional glider is steeper than the energy-consumption-equivalent glide angle, the positive buoyancy glider has a higher sailing efficiency, whose energy consumption per meter is irrelevant to the glide angle.