Hiroaki Kobayashi

Experimental Study of a variable geometry axisymmetric air intake (inlet) for ATREX engine has been done at ISAS supersonic wind tunnel and NASA GRC 1-by 1-foot supersonic wind tunnel since 1993. More than 13knds of subscale intake models whose cowl inlet diameter is 123 mm are tested and intake aerodynamic performances such as total pressure recovery and mass capture ratio are obtained. Each intake has the peculiar characteristics such as high mass capture type, high total pressure type. Some of these intakes attained the target of the development study from the viewpoint of intake aerodynamic performances at the limited Mach number range. The configuration of the supersonic diffuser passage is designed using the computer program that employs the method of characteristics and the configuration of the subsonic diffuser passage is designed using the axisymmetric CFD. The performances under off-design condition are also investigated by the CFD in parallel with the wind tunnel tests. By several trials of design and tests, intake design method was established. Furthermore off-design performances such as the bleed pattern of the spike and the cowl, the shape of the spike and the cowl tip, spike boundary layer transition point, and the angle of attack are investigated. And several proposals to improve the aerodynamic performances are done. Because the boundary layer on the spike is thicker than the cowl, bleed from the spike is more important to improve the total pressure recovery. A boundary layer transition system at the tip of the spike is necessary for the flyable intake model.