Effects of wind-tunnel disturbances on hypersonic boundary-layer transition. I, II.

An experimental investigation of the dependence on facility disturbance of transition on sharp cones has been made. In Part I, the sound radiated from the turbulent boundary layer on the walls of several facilities was measured with pressure transducers mounted flush with the cone surface. In Part II, a constant current hot-wire anemometer measured free-stream and cone shock layer disturbances in two hypersonic helium tunnels. Comparison of hot-wire results with surface pressure measurements in one of the helium tunnels indicate the latter data provide an accurate indication of the facility disturbance levels. Both studies show that transition Reynolds numbers correlate in terms of facility rms sound disturbance levels provided the laminar boundary layers on the models are similar.