Development study on axisymmetric air inlet for ATREX engine

A development study of variable geometry axisymmetric inlet has been done at ISAS since 1993. Total pressure recovery and mass capture ratio of the inlets are obtained by the wind tunnel tests at ISAS supersonic wind tunnel and NASA GRC 1-by 1-foot supersonic wind tunnel. In Feb 2000, a control test of an inlet is conducted at ONERA S3MA supersonic wind tunnel to accomplish an automatic operation of the inlet. As a result, we succeeded in controlling the inlet automatically and about 90% of the maximum inlet performances are achieved without manual operation. The configuration of the supersonic and subsonic diffuser is modified to increase the mass capture in the subsonic flight without the increase of the total pressure loss in the supersonic flight, and new type of inlet configuration is designed (Type-M). Although, type-M inlet can make 75% of total pressure recovery at Mach 3.5, it is necessary to improve the bleed system of the spike surface. A flyable inlet model whose cowl diameter is 740mm is now on the drawing board.