Optimization Design And Dynamic Analysis Of Hydrofoil Mechanism Of Wave Glide

Wave glider is a new type of the sea surface unmanned observation platform,which is mainly composed of a surface float,a submerged glider and an umbilical cable.It can convert wave energy into its forward propulsion force,and electric energy can be obtained by using the solar panels installed in the surface float,which can realize largescale,unmanned,and long-range autonomous cruise.The speed of the wave glider is an important index to evaluate its performance.The greater the speed,the stronger the anti-ocean current ability and the higher the position control accuracy.However,the dual body structure of the wave glider causes the asynchronous movement of the surface float and the submerged glider,which produces the umbilical cable inclination angle.The wave energy and the forward speed of the wave glider are lost by the umbilical cable inclination angle.Therefore,it is a great significance to develop a submerged glider with special hydrofoil swing mechanism.Aiming at this problem,the following research work is carried out:Firstly,the working principle of the wave glider is introduced.To solve the loss of wave energy caused by the umbilical cable inclination angle,a mechanism named lower-limit mechanism is designed,which can automatically adjust the lower limit of hydrofoil swing(The maximum swing angle of hydrofoil in the counterclockwise direction)according to the umbilical cable inclination angle;the force on hydrofoils of the conventional hydrofoil swing mechanism in the rising and falling stages are systematically analyzed,the advantages of the lower limit follow-up mechanism and its motion mechanism in different sea conditions are systematically explained.Secondly,the three degree of freedom dynamic model of the wave glider is established by using Newton-Euler method,the un-synchronized movement of the wave glider in the vertical plane is analyzed by numerical calculation method,and the theoretical basis of simulation software and numerical simulation are briefly explained.Thirdly,the optimized hydrofoil mechanism is simulated by using the commercial Computational Fluid Dynamics(CFD)software FLUENT,the forward thrusts the swing angle of a pair of hydrofoils under different spring stiffness coefficients and follow-up angles are analyzed,and the simulation results are compared with the conventional submerged glider.Finally,the prototype is made through adding a set of parallelogram mechanism on the conventional submerged glider,and the follow-up of the lower limit of the hydrofoil swing and the umbilical cable is realized.The tank experiment of the prototype is carried out to verify the effectiveness of numerical simulation,and the superiority of the lower limit follow-up submerged glider under real sea conditions is verified by sea trial.The research provides a theoretical basis and a reference for the performance improvement of wave gliders.