Incipient separation of a laminar boundary layer was experimentally investigated on a blunted cylinder-flare configuration at zero angle of attack. Conical flares with various angles were tested with each of three nose shapes in air at a nominal Mach number of 15. The nose shapes included a spherical-tipped cone, a hemisphere, and a flat face. Equilibrium stagnation temperature was about 36OO0 R, and the surface temperature of the models was about 550° R;thus the boundary layers on all models were highly cooled. The Reynolds numbers, based on free-stream properties for equilibrium flow and on cylinder diameter, were about 2400 and 6200. Incipient separation was believed to occur at a flare angle between 35° and 40° for all three nose shapes. A comparison of the present data with previously published data showed that the very low Reynolds number and substantial boundary-layer cooling of the present tests were highly favorable for maintaining an attached boundary layer for very large flow-deflection angles.
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