Research On Design And Hydrodynamic Performance Of "Seagull" Underwater Glider

Underwater gliders are a type of autonomous underwater vehicles which don't use external active propulsion systems.By changing its net buoyancy and the center of gravity position,it can glide in sawtooth motion and spiraling motion.As a novel underwater observing platform,underwater gliders are characterized with long endurance,low energy consumption,long range,low cost and easy operation.Nowadays,underwater gliders have been widely used in ocean environment monitoring,marine biology research,oil & gas industry engineering and so on.Therefore,developing underwater gliders is of great significance to the development of China's marine industry.In this study,a 500-meter-depth prototype underwater glider has been developed with the help of project support.It is capable of monitoring in vertical direction.Besides,this paper describes the system design and hydrodynamic calculation methods of “Seagull” glider in detail.The main research work is outlined as follows:The underwater glider includes buoyancy adjusting mechanism,attitude adjusting mechanism,control system,communication & position system and general structure.Moreover,the buoyancy adjusting mechanism is able to measure the volume of displacement accurately.The attitude adjusting mechanism can adjust both pitch angle and roll angle.Domestically developed Control system can control buoyancy adjusting mechanism,attitude adjusting mechanism and sensors,collect and store data.The general structure can meet the requirement of subsystems' layout and its structural strength is satisfied with operational requirement.The hydrodynamics force of an underwater glider include inertia hydrodynamic force and viscous hydrodynamic force.Both potential Hess-Smith method and CFD method which simulates Planar Motion Mechanism test are applied to obtain the inertia hydrodynamic force of “Seagull” glider.By describing principles and procedures of two methods and comparing the results,the advantage and disadvantages of two methods can be concluded.CFD method is applied to simulate the direct and oblique flights of “Seagull” glider in order to obtain the viscous hydrodynamic force.Furthermore,this paper describes the principles,equipment and procedures of model towing test.It verifies that the accuracy of CFD method is satisfied with the engineering requirement.In addition,the vertical motion and field experiments of “Seagull” glider are analyzed,which further verifiy the accuracy of hydrodynamic results.