Shock-induced separated flows on the lee surface of delta wings

Abstract

Experiments were conducted to study shock-induced separated flows on the lee surface of delta wings with sharp leading edge at supersonic speeds. Two sets of delta wings of different thickness (10° and 25° normal angle), each with leading edge sweep angles varying from 45° to 70°, were tested. The measurements, carried out in a Mach number range from 1.4 to 3.0, included oil flow visualisations (on both sets of wings) and static pressure distributions (on the thicker wings only). Using the test results, some features of shock-induced separated flows, including in particular the boundary between this type of flow and fully attached flow, have been determined. The experimental results indicate that this boundary does not seem to show any significant dependence on wing thickness within the limit of thicknesses tested. It is shown that this boundary can be predicted for thin delta wings using a well known criterion for incipient separation in a glancing shock wave boundary layer interaction, namely that a pressure rise of 1.5 is required across the shock. Comparison of the predicted boundary with experimental results (from oil flow visualisations) shows good agreement.

Possible types of flow on lee-surface of delta wings at supersonic speeds

“…The position of the shock wave calculated using the method given in Ref. 19 is shown in the figure as W/. This flow, termed type 5, has also been observed in earlier investigations.…”

“…In summary, it can be stated that a change in wing thickness does not result in qualitative changes in the types of flow that occur on the leeside of delta wings. The differences between thin and thick wings as evidenced by the earlier results of Miller and Wood" 3 ' and Szodruch 19 ' would seem to be due to differences in the interpretation of flow visualisation data. The present study does not suffer from this drawback since oil flow patterns on both the thin and thick wings were obtained using the same technique and furthermore, precisely the same criteria were used to interpret the results.…”