Delay or control of flow separation for enhanced aerodynamic performance using an effective morphed surface

This paper investigates an improvement of the aerodynamic performance of a wing at high, including post-stall angles of attack by re-designing its camber line to control the separation of its boundary layer. This is experimentally implemented using an Aluminum secondary skin on the wing surface, which aligns itself to the separated boundary layer at high angles to attack, such that the flow remains attached to it, which otherwise would have separated on the baseline configuration. The shape of the skin, which is now regarded as the active flow surface, is essentially a morphed version of the baseline shape of the wing and is predicted numerically using an in-house code based on a ‘decambering’ technique that accounts for the local deviation of camber by accounting for the difference in the coefficients of lift and pitching moment predicted by viscous and potential flows. This technique is tested on a rectangular planform using different wing sections, NACA0012, NACA4415, and NRELS809. The effective morphed flow surface is also used for the baseline wing to operate at a design local 2D Cl, which is obtained by incrementing the baseline Cl by a user defined percentage at design pre and post-stall angles of attack. Aerodynamic characteristics of the effective morphed configurations using numerical analysis, CFD, and wind tunnel experiments are reported.