Boundary layer transition measurements on the AEDC 10 degrees cone in three RAE wind tunnels and their implications

Abstract

The AEDC 10° cone has been tested in a large number of American transonic wind tunnels to investigate the influence of free stream pressure fluctuations on transition Reynolds numbers. Measurements made on the AEDC cone in three RAE wind tunnels are described in this Report. In the RAE 8ft x 8ft subsonic/supersonic tunnel the cone transition Reynolds numbers were relatively high and the pressure fluctuations low. In the RAE 3ft x 4ft high supersonic speed tunnel the transition Reynolds numbers were high and there were strong unit Reynolds number effects. In the RAE 8ft x 6ft tunnel transition was controlled by an effective roughness, either at the cone tip or the microphones; the tunnel pressure fluctuations varied appreciably with Mach number and were high at subsonic speeds. The results show that surface pressure fluctuation measurements at supersonic speeds are sensitive to the degree of smoothness of the surface, particularly in the transition region of the boundary layer. A tentative classification of the aerodynamics facilities used for transition tests is suggested.