The experimental study of aerodynamics and flow structures of a wing with Gurney flaps in ground effect
XIAO Tao;Daichin;Shanghai Institute of Applied Mathematics and Mechanics,Shanghai University;Shanghai Key Laboratory of Mechanics in Energy Engineering,Shanghai University;
An experimental study on the lift/drag forces,tip vortices and wake flow of a NACA0012wing with Gurney flaps(GF)in ground effect is introduced.The goal of the study is to investigate the influence of the flow structure on the aerodynamics of the wing in ground effect.The experiment was carried out in a wind tunnel,the Reynolds number is 8×104 based upon the chord length of the wing.The lift/drag forces are measured on conditions of various ground heights and angles of attack.The velocity distributions of tip vortices are measured by a 7-holes probe scanning.The results show that the lift force of the Gurney flaps increases significantly compared with that of a wing in free space at same angel of attack.Compared with that of a clean NACA0012wing,the drag force of a wing with Gurney flap increases as well,leading to the decreasing of the lift-to-drag ratios of the Gurney flap than that of a clean wing,when the angle of attack is larger than 2°.However,an easy curve of the lift-to-drag ratios to the angle of attack without obvious peak value is observed,which implies the pitch stiffness of the wing with Gurney flaps is improved.The tip vortices of the wing is stressed due to the ground effect,and moves gradually to the wing tip outboard,therefore,the down-wash flow induced by the tip vortices is weakened.Moreover PIV technique was used to measure the influence of ground effect to the velocity distribution around the Gurney flap as well.
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