Boundary-layer measurements on 15-deg and 24.5-deg cones at small angles of incidence at M = 3.17 and 3.82 and zero heat transfer

Abstract

Transition measurements on 15-deg and 24.5-deg cones at MCD = 3.17 and 3.82 showed that the transition front was extremely sensitive to incidence, a fourfold variation occurring between transition Reynolds numbers on the leeward and windward sides of the 15-deg cone at 2-deg incidence. At zero incidence the transition Reynolds number was between 2.5 and 3.0 x 10power6 and no significant variation was observed over the test range of stagnation pressures from 2 to 5 atmospheres. Pitot traverses on the top generator of the 15-deg cone at MCD = 3.17 showed that the effects of small angles of incidence (- 2 deg to + 1 deg) on the characteristics of the laminar boundary layer were nearly linear and were in excellent agreement with the theory of F. K. Moore. The same results showed that small angles of incidence altered the thicknesses of both laminar and turbulent boundary layers, but did not affect the shapes of the velocity profiles. The alteration with incidence of the displacement thickness of the laminar boundary layer was large (agreeing with Moore's theory), and in amount was more than twice that found with a turbulent boundary layer.