Test Techniques for High-Lift, Two-Dimensional Airfoils with Boundary Layer and Circulation Control for Application to Rotary Wing Aircraft.

Abstract : Extensive testing experience with very high lift mono-element blown airfoils to be employed by rotary wing aircraft has necessitated the development of unconventional two-dimensional test techniques. Both experimental and analytical results are presented which should assist future investigators in conducting similar tests accurately. The primary problem of high lift two-dimensional testing, wall boundary layer separation due to severe adverse pressure gradients on the model, is discussed as are the serious errors introduced by this phenomenon. A detailed discussion is presented concerning the additional considerations which must be given to blown airfoil testing. Such additional test problems as wall and blockage corrections, Reynolds number effects, leading edge separation, and flow visualization are addressed.