Hypersonic Turbulent Boundary Layer with Pressure Gradients and Cross Flow

J experimental and theoretical investigation of the hypersonic compressible turbulent bounary-layer undergoing both normal and longitudinal adverse pressure gradients and cross flow is presented. The investigation is confined to the plane of symmetry on a compression flare in order to simulate the conditions existing at the centerline on an inlet of a jet engine. The cross flow is induced by connecting two lateral curved plates symmetrically on the sides of the flare. The integral equations of the compressible turbulent boundary-layer, which include terms referring to the cross flow, are solved numerically. Content The experiments were performed in a Mach 6 blowdown axisymmetric wind-tunnel, with a stagnation temperature of 800°R, a stagnation pressure of 1900 psia, and a freestream Reynolds number of 4.4 x 10 7 per foot. The model consisted of a streamlined centerbody followed by a compression flare 6.3 in. in length. The maximum turning angle of the flare was 43°. The over-all axial length of the centerbody, from the nozzle throat to the test section, was 77.3 in. The compression flare was equipped with pressure taps to measure the longitudinal and the peripheral pressure distributions, and thermocouples were used to measure the heat-transfer rates at the wall. The static pressure, total pressure, and total temperature profiles in the direction normal to the compression flare were measured with traversing probes at nine locations along the flare. Subsequently, the compression flare was cut laterally to connect two lateral curved plates symmetrically placed on each side of the flare to create an expansion in the peripheral direction and establish a favorable cross flow (C.F.), in addition to the normal and longitudinal pressure gradients. Because of the large variation in the turning angle of the flare, the wall pressure increases from the freestream static pressure to a value approximately fifty times greater. The tests show no separation of the naturally established thick turbulent compressible boundary-layer along the centerbody. With the same initial conditions at the beginning of the compression flare, an inviscid method of characteristi cs solution shows that the compression waves coalesce into a shock outside the boundary-layer at the terminal part of the compression flare.