A new hypothesis for transition on the windward face of the Space Shuttle

Abstract

This paper introduces the hypothesis that roughness induced transition of the attachment-line boundary layers is important for the flow over the windward face of the Space Shuttle. Attachment-line transition is described for the flow over a swept cylinder. The available knowledge is then used to model transition on a slender delta wing at large angles of incidence. This is compared with wind-tunnel data for roughness induced transition on the Space Shuttle. Agreement between the hypothesis and data is good and a simple transition onset criterion is proposed. This is completely general and can, in principle, be applied to vehicles of any shape. Finally, it is shown that the hypothesis provides an explanation for the instantaneous forward flash of the transition front that was observed on the Orbiter Columbia. Nomenclature A = constant b - semispan of delta wing d - diameter of circular trip wire k = characteristic dimension of roughness element L = length of Space Shuttle model M = Mach number Q = resultant velocity (U1 + V2)1/2 R = attachment-line similarity parameter Rk = roughness Reynolds number (Uk - k/v) r = leading-edge radius s = trip (roughness)-detector separation measured along the attachment line T = temperature U, V — velocity components in the x and y directions, respectively