Concerning the annular air intake in supersonic flight

Abstract

The stability of an annular air intake at a Mach number of 1.4 and with Reynolds numbers of about 1.5 x 10power6 is considered in detail and a method is described whereby the experimental results might be extrapolated for preliminary full-scale design purposes. This extrapolation has yet to be checked experimentally, but suggests that a typical aircraft intake would have an overall isentropic efficiency of about 85 per cent. The results also indicate that both the stability and the efficiency of an intake could be improved by controlling the boundary layer on its nacelle, and as an alternative to boundary-layer suction a device which is described as a segregation ring is suggested. This, it appears, might raise the efficiency by some 2 or 3 per cent.