Study On The Hydrodynamic Characteristic Optimization Of Variable Hydrodynamic Shape Water Jet Hybrid Underwater Glider

The water-jet hybrid underwater glider(WJHUG)is a new type of hybrid underwater glider equipped with pump-jet propellers.It combines the advantages of traditional autonomous underwater glider(AUG)and autonomous underwater vehicle(AUV),can achieve saw-tooth gliding motion,fixed depth propulsion motion.Since the optimal hydrodynamic shape required in different sailing modes are not consistent,the single hydrodynamic shape configuration of the platform can no longer meet the application requirements of multiple-modes sailing.Inspired by flying fish’s variable-wing movement,the concept of variable hydrodynamic shape WJHUG was proposed.Through variable hydrodynamic shape structure,WJHUG can adjust its wings anytime according to different sailing status to adapt to different mission requirements,and in a result improving the hydrodynamic performance of platform and improving the sailing efficiency.The main development of this paper are as follows:1.Using the bionic flying fish foldable wing structure for reference,the conceptual design of the variable hydrodynamic shape WJHUG was proposed,and the feasibility of the conceptual design was verified.2.Based on the design requirements of the variable hydrodynamic shape and combining the existing buoyancy adjustment hydraulic system of the vehicle,the buoyancy adjustment system is integrated with the variable wing hydraulic drive system,and an integrated hydraulic system scheme is proposed.3.Aiming at the optimization of the fairing attachment of variable hydrodynamic shape structure,from the perspectives of design point set sampling,optimization model construction,and optimization algorithm,this paper proposes a comprehensive hydrodynamic optimization process based on the LHD sampling method,the Kriging response surface and the MOGA optimization algorithm.4.Based on the different performance requirements of WJHUG in different sailing modes,and from the perspective of hydrodynamic performance and vehicle stability,the optimization principle of the variable hydrodynamic shape WJHUG in AUG gliding mode and AUV propulsion mode is proposed.Combined with the genetic algorithm,the optimization of the variable hydrodynamic shape structure’s morphing strategy has been finished.The comparison between the optimization results and the original model shows that the hydrodynamic performance of the vehicle has been greatly improved,and the lift-to-drag ratio performance of the AUG gliding mode before optimization is increased by 9.4%;The sailing resistance of AUV propulsion mode is reduced by 7.2%.