Theoretical and experimental internal flow characteristics of a 13.97-centimeter-diameter inlet at STOL takeoff and approach conditions

The theoretical and experimental internal flow characteristics of a 13.97-cm-diam inlet with centerbody retracted and extended are presented at STOL takeoff and approach operating conditions. The theoretical results were obtained from incompressible potential flow corrected for compressibility and boundary layer. Comparisons between theoretical internal surface static-pressure distributions and experimental data are presented for free-stream velocities of 0, 24, 32, and 45 m/sec for a range of inlet incidence angles from 0 to 50 deg. Surface static-pressure distributions are illustrated at circumferential locations of 0, 60, 120, and 180 deg. Surface Mach number distributions from the stagnation point to the diffuser exit are presented along with turbulent boundary-layer shape factors. In general, good agreement was found between the theoretical and experimental surface static pressure distributions.