Supersonic Testing of Natural Laminar Flow on Sharp Leading Edge Airfoils. Recent Experiments by Aerion Corporation

Abstract

Though inviscid drag can be the biggest component of drag on supersonic aircraft, viscous drag reduction can account for a major improvement in total drag. A significant reduction in viscous drag can be achieved by extensive laminar flow on the wings, which can be obtained by carefully designing the airfoil’s pressure gradients. This tailoring of the design is more difficult if supercritical airfoils in conjunction with high leading edge sweep are adopted. In such case the extent of laminar flow is reduced due to either adverse pressure gradient early in the boundary layer development and/or growth of cross flow instabilities. A way of avoiding these issues is to unsweep the wing and adopt biconvex-type sharp leading edge airfoils. This concept has been tested and adopted by Aerion Corporation and test results showing extensive runs of natural laminar flow (NLF), both in ground facilities and in flight, are summarized.