An experimental investigation was conducted in a stream of Mach number 1.88 to determine the performance characteristics of a side inlet operating in the presence of initial boundary layer but alined at zero angle of attack and zero yaw with the free stream. The supersonic diffuser consisted of half of a 50°-conical-spike inlet mounted on a flat plate. The subsonic portion of the diffuser was faired into a cylindrical combustion chamber. Boundary-layer removal was accomplished upstream of the inlet by means of a ram-type scoop of variable height'. The initial boundary-layer thickness was also varied.nWith complete removal of the initial boundary layer upstream of ,the inlet, a total-pressure recovery of approximately 89 percent was obtained. Allowing all the initial boundary layer to flow into the inlet lowered the inlet total-pressure recovery to approximately 70 percent although the initial defect in total pressure in the boundary layer did not greatly affect the average total pressure upstream of the -inlet. Most -of the additional losses were determined to occur in the subsonic portion of the diffuser.nThe inlet pressure recovery with a simple ram-type scoop having a straight leading edge decreased markedly with decreasing boundary-layer-scoop mass-flow ratio. Several boundary-layer-removal systems were briefly investigated which greatly reduced this sensitivity.nThe inlet was subject to large total-pressure losses when operating at zero forward velocity and high throat velocities.
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