Flight Testing of Laminar Flow Control in High-Speed Boundary Layers

Abstract : This paper presents data from a series of laminar-flow flight tests at NASA Dryden flight Research Center on the F-15B. It is shown that periodic discrete roughness elements near the leading can increase the laminar flow region at both supersonic and subsonic flight Mach numbers. Infra-red thermography was used to visualize laminar-turbulent transition. Although the experiment was designed for Mach 1.85, it was possible to obtain data at other Mach numbers as well. the results at Mach 1.85 and 0.911 are presented. Unfortunately, flowfield nonuniformities limited the Mach number range and the extent of observed laminar flow. The results are encouraging that periodic discrete roughness elements near the leading edge can be used as a laminar flowing control technique.