Effect of Sides-Spillage from Airframe on Scramjet Engine Performance

Precompressionbythewindwardsurfaceoftheaerospaceplaneisnecessaryforthescramjetoperation.However, this precompression causes spillage from the high-pressure windward surface toward the sides of the aerospace plane. To examine the effects of the sides-spillage, performance of a scramjet engine was evaluated with a onedimensionale owmodel,and payloadto thelowEarthorbitwasestimated withthee ightsimulationofan aerospace plane.Priorto thesimulation, testswithscramjetinletmodelswereconducted in aMach 4 wind tunnel to grasp the primary features of the sides-spillage to support the simulation. The models were inclined from the e ow direction to simulate the skewed e ow near the side of the plane during sides-spillage. The experiments proved that the aerodynamic performance of the inlet was not affected by the inclination for the given entrance Mach number to the models. However, the mass capture ratio decreased as a result of the reduction of thedensity of aire ow through the expansion. In the numerical estimation the sides-spillage was modeled not to reduce the performance of the inlet, but to reduce mass e ow to the inlet. The resulting decrease of delivered aire ow to the engine as a result of the spillage reduced the thrust by 15%, while the corresponding payload decreased about 60%. Side fences were effective in preventing spillage.