Flare-Induced Interaction Lengths in Supersonic, Turbulent Boundary Layers

Abstract

Experimental results are presented for the effects of Mach number, Reynolds number, and corner angle on flare-induced separation of a supersonic, turbulent boundary layer. Measurements were obtained for upstream interaction distance ℓ_0 from the flare to the beginning of the interaction for Mach numbers 2≤M≤4.5, boundary-layer thickness Reynolds numbers 10^5 < R_δ < 10^6, and adiabatic wall conditions. Flares of angle α≤40° were attached to a hollow-cylinder model of 12 in. diam at either x_c= 14 or 18 in. downstream from the sharp leading edge. It was found that ℓ_0/δ_0 decreases with increasing Mach number and Reynolds number and increases with flare angle. For constant α, when ℓ_0/δ_0 is plotted vs the local skin-friction coefficient, C_(f0), the Mach number dependence disappears. From this observation, a simple correlation formula was obtained and used to compare results from other investigations, and also to correlate incipient separation data.

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