Mach Effects On Circulation Control and Jet Flap Airfoils

I. Abstract This work presents a continuing effort to explore the capabilities of circulation control technology. A validation for the NCCR 7067 airfoil is presented to support Computational Fluid Dynamics simulations for elliptic circulation control airfoils. Mach effects on the performance of an elliptic circulation control airfoil is presented. Simulations were conducted up to a Mach number of M = 0.5. The well known Pandtl-Glauert compressibility correction is found to be suitable for application on circulation control lift curves (with respect to the jet momentum coefficient). It is shown that the time characteristics of the elliptic airfoil in response to a step input in the momentum coefficient are similar to those of the closed forsolution of Wagner for the response of a flat plate to a step input in the angle of attack. This results is not affected by Mach number or jet momentum step amplitude. On a jet flap airfoil, a certain jet momentum coefficient was found to be required to attach the flow on a 40 ◦ flap deflection. The critical jet momentum coefficient was found to be increasing with the Mach number. The step like behavior suggests that non-linear