Experimental and Numerical Investigation of Aerodynamic Performance of Airfoils Fitted with Morphing Trailing-edges

Experimental and numerical studies to characterize the aerodynamic and aeroacoustic performance of a simple NACA 0012 airfoil fitted with various morphing flaps have been successfully carried out. The airfoil was tested with various flap configurations having different camber profiles with a flap deflection angle of β = 10^◦. Comprehensive aerodynamic measurements including lift and drag forces, wake flow and pressure distribution over a wide range of angles of attack and chord-based Reynolds numbers were carried out. A detailed Detached Eddy Simulation (DES) has been performed for two angles of attack α = 0^◦ and 4^◦ and two types of flaps to further investigate the airfoil’s flow behaviour and the noise generation mechanism. The experimental and computational results show that the camber profiles of the morphing flaps significantly affect the aerodynamic and aero-acoustic performances. Flow measurements showed that the downstream wake development can also be influenced as a result of changing the flap profile. It was found that highly cambered flap profiles provide higher lift coefficients and increased maximum lift coefficient compared to moderately cambered profiles while the lift-to-drag ratio slightly decreases. Contour plots using iso-surfaces of Q-criterion show that the separation near the trailing-edge is further delayed at high angles of attack for airfoils with highly chambered morphing flap. The far-field noise was calculated using Curle’s analogy and it showed an increased noise for highly cambered flap, which corresponds to the increased pressure distribution, turbulence and wall-spectral levels. This study shows that the effective design space of the morphing flaps can be expanded taking into account the optimal aerodynamic performance requirements. The study also suggests that in order to achieve optimum aerodynamic performance, independent surface morphing of the suction and pressure surface camber will be required to delay the onset of flow separation.