Experimental investigation on the influence of a Mini-TED on the flow separation of an airfoil at low Reynolds number using PIV

The wind tunnel experimental results of flow structures of a NACA23012 airfoil mounted with a rearward Mini-TED for low Reynolds number situations are introduced in this pa-per.The PIV technique was applied to capture the velocity fields around the airfoil for different angle of attack,and the detailed vortex structures near the trailing edge were measured as well. The velocity measurement results are compared with those of NACA23012 prototype airfoil,so as to investigate the influence of the Mini-TED on the flow separation characteristics above the airfoil surface.The Reynolds number is Re≈1.3×105 based upon the chord length of the airfoil. The results show that the flow separation on the suction surface of the airfoil,especially for the case of larger angle of attack,is obviously depressed due to the installation of Mini-TED,and the flow speed on the suction surface is much higher than that of NACA23012 prototype airfoil.A low speed region is locally formed in front of the Mini-TED,which leads to the increase of static pressure.Meanwhile,a double-vortex structure with low pressure is observed behind the Mini-TED.The resulting pressure difference causes the extra lift increment near the trailing edge of the airfoil,and the pitching moment is increased as well.The velocity differences between the suction surface and the pressure surface of airfoil with the Mini-TED are higher than those of the NACA23012 prototype airfoil,which can contribute to the increment of lift force.