A Hybrid Buoyancy Engine For Deep-sea Mobile Float:Design And Application Research

Buoyancy engine is the key technology in the development of profiling floats and underwater gliders.Profiling floats and underwater gliders are commonly applied in surface water of 0-2000 m.In recent years,the need of extending the application area of profiling floats and underwater gliders to the deep sea brings new challenges to buoyancy engine technology.From surface water to deep water,higher pressure-bearing ability and greater buoyancy regulation amount are required,and the energy consumption will be increased dramatically if adopting the traditional design of buoyancy engine,which will cause the reduction of the equipment endurance.In this paper,a hybrid buoyancy engine based on depth-varying ocean pressure was carried out,it can make full use of the depth-varying ocean pressure to achieve a more efficient profile motion of profiling floats and underwater gliders,reduce the energy consumption effectively,and provide key technical support for the development of large-depth ocean autonomous observation platform.This paper is divided into two parts.On the one hand,aiming at designing a low-power buoyancy engine for the newly developed multimode deep-sea mobile float,a hybrid buoyancy engine with compact structure,modularization,low power consumption,volume controllability and energy storage by using depth-varying ocean pressure,is designed based on the successful experiences of the existing buoyancy engines at home and abroad.The simulation tests are carried out based on the AMESim hydraulic simulation software,the results show that the hybrid buoyancy engine is capable to function normally under different pressure loads and meet the technical requirements.Therefore,the design is reasonable and feasible,which provides a basis for the further development of the system.On the other hand,aiming at application of the hybrid buoyancy engine in the deep-sea mobile float,the motion behavior of the float driven by the engine are theoretically modeled and simulated.Based on the working characteristics of the deep-sea mobile float,two modes of profiling float and underwater glider are studied with the consideration of the influences caused by the depth-varying ocean environment.In the study of the motion behavior of the deep-sea mobile float in profiling float mode,it is found that the energy accumulator accelerates the motion of floats,with only a smaller change of net buoyancy required to complete a profile motion,however,the nitrogen floats take longer time than the conventional ones to reach the same depth,with a weaker stability of depth keeping.In the study of the motion behavior of the deep-sea mobile float in underwater glider mode,it is found that energy accumulator has advantages to compensate the negative effects of depth-varying ocean environment on glider motion.