Air condensation effects measured in the R.A.E. 7 in. x 7 in. hypersonic wind tunnel

Abstract

It is important to study the effects of air condensation in hypersonic wind tunnels and to establish the degree of supersaturation achievable because savings in heating requirements or increase in Mach number may be achieved. The degree of supersaturation measured in this tunnel shows that with the present heater the upper limit on Mach number may be extended from M = 9 to M = 12. Proof testing of models is required to establish that results in supersaturated flow agree with those obtained in subsaturated flow because localised condensation effects in expansion regions may occur. Integrated pressure distributions on a Nonweiler wing show that sub- and super-saturated flows give similar results but that condensing flow shows differences in c~p on the suction side at low incidence and on the windward side at high incidence, which results in a decrease in L/D max without friction of about 10 per cent.