Experimental and numerical investigation of aerodynamic performance for airfoils with morphed trailing edges

The aerodynamic performance of a NACA 0012 airfoil fitted with different flaps were studied experimentally and numerically. Comprehensive aerodynamic measurements including pressure distribution, lift and drag forces and wake flow for airfoils with different mean flap camber profiles were carried out over a wide range of angles of attack and chord-based Reynolds numbers. The results show that the mean flap camber profiles significantly affect the aerodynamic performance and the downstream wake development of the airfoil. It was found that the highly cambered flap profiles provide higher lift coefficients compared to the moderately cambered flap profiles, with an insignificant reduction in the overall lift-to-drag ratio. Furthermore, the Q-criterion iso-surface results show that the separation near the trailing-edge is further delayed at high angles of attack for airfoils with high mean flap camber. This study shows that the effective design space for flaps with morphing capabilities can be expanded by taking into account the optimal aerodynamic performance requirements. The study also suggests that in order to achieve optimum aerodynamic performance, an independent surface morphing of the suction and pressure surface camber will be required to delay the onset of flow separation.