Analysis for Obtaining High Lift Pressure Distributions for Transonic Airfoils.

This report describes the development of a method for obtaining an optimum pressure distribution over the suction side of an airfoil operating in the transonic speed regime. The pressure distribution is optimum in the sense that maximum lift on the airfoil section is desired while the flow over the airfoil remains fully attached. The development allows for shocked and shock free flows over the airfoil with a compressible and mixed laminar-turbulent boundary layer. The boundary layer is typically maintained on the verge of incipient separation over the rearward stretch of the airfoil. The pressure recovery distribution is obtained from a compressible extension of Stratfords incompressible turbulent boundary layer separation criterion which is also given in the report. A variational problem for maximum lift is formulated and solved to yield the location of the onset of the pressure recovery and the pressure distribution forward of this point. Author