An Inverse Method For The Design Of Airfoils With Supercritical Flow

An iterative-direct method is described for designing airfoils with regions of supercritical flow which are nearly shockless. The method uses a wave analysis diagram in the supercritical region to determine design values leading to near shockless characteristics. The pressure distributions are calculated using an available viscous, supercritical method which solves the full, non-linear potential equations for transonic flow. Repeated application of the method enables airfoils to be designed with good off-design behaviour. Results are presented for the design of an 18% thick airfoil and it appears that drag rise Mach numbers about 0.74 are feasible at a lift coefficient of 0.35.