Study On Surface Sailing Characteristics Of The Wind Powered Vehicle With Deployable/Foldable Wing Sail

The Wind Powered Vehicle(WPV)is a new type of vehicle driven by wind energy.With the driving force provided by automatic sail,the WPV can achieve long-time inplace observations for the meteorological and hydrological parameters of large-scale ocean surface layer,only with a small number of battery to supply sensors and motors.As the driving module of the WPV,the wing sail has critical influence on its sailing characteristics.At present,the traditional wing sail module does not have the variable area,and thus fails to adapt to the changing wind speeds and directions.In this paper,a novel design scheme of deployable/foldable wing sail is presented to accommodate the changing wind speeds and directions.Based on the computational fluid dynamics(CFD)software ANSYS-FLUENT,the calculation method of sailing characteristics of the WPV is established by integrating wind model and force model of the vehicle.Meanwhile,the sailing characteristics of WPV with deployable/foldable wing sail are studied at different wind speeds,wind directions,angles of attack and areas of wing sail.Achievements of the present research can provide an important theoretical reference for design of the high performance WPV.Inspired by the deformation mode of marine swordfish dorsal fin,a novel design scheme of deployable/foldable wing sail with single degree of freedom is proposed to adapt to the changing wind speeds and directions on the sea surface.The deployable/foldable wing sail is composed of the wing sail structure,the self-locking mechanism and a wire-driven assembly.The wing sail structure can be locked in a specific position by the self-locking mechanism,so as to realize four kinds of area configurations of wing sail.In addition,a larger folding rate of 92% can be realized from the fully deployed to the fully folded state.With the variable area,the area and the angle of attack can be adjusted to achieve better aerodynamic performance according to different sailing conditions.Therefore,the WPV can sail autonomously in different wind conditions for a long time.Based on the steady-state sailing mechanism of the WPV,the wind model,force model in horizontal plane,and the moment model at the transverse section of the vehicle in the heeling state are established.The aerodynamic parameters of the wing sail and hydrodynamic parameters of the WPV are solved using the computational fluid dynamics(CFD)software ANSYS-FLUENT.Based on deformation mechanism of the deployable/foldable wing sail,the center-of-mass position of different forms of wing sail are calculated.The calculation method for sailing characteristics of the WPV is established through integrating the wind model and force model of the vehicle in the heeling state.The influence of angle of attack,area of the wing sail,outside wind speed and wind direction on the sailing characteristics is studied.The results show that the WPV can reach a higher speed and a suitable heel angle by adjusting the wing sail to a suitable angle of attack and area corresponding to different wind speeds and wind directions.Therefore,the WPV has a relatively stable sailing.The experimental model of the WPV is designed and the tank test is conducted.The sailing speeds and heel angles of the WPV during steady-state sailing are obtained at the conditions with specific wind speed,different wind directions,different angles of attack and areas of wing sail.Compared with results of the tank test,the errors of the sailing speeds and heel angles obtained from the proposed calculation method are within 20%.The tank test shows that the proposed calculation method for sailing characteristics is reliable and can be used to guide the following optimization design of the WPV.