Improvement of the performance of a supersonic mottle by riblets

This paper describes an experimental study of supersonic internal flow over a riblet surface mounted on a channel wall to reduce pressure loss and imp rove the performance of a supersonic nozzle. The magnitude of the static pr essure in the pressure-rise region observed in channels with riblet surface became lower than that for a smooth surface, and the significance of its d ifference was indicated by uncertainty analysis estimated at 95 percent cov erage. The Mach number distributions obtained by traversing a Pitot-tube sh owed that the separation point moved downstream and the size of the separat ion region became small when using riblets. Furthermore, it was found that the stagnation pressure loss reduction was as large as 56 percent in the un iform supersonic flow field at a Mach number of 2.0, and 29 percent in the separation region. [S0098-2202(00)00103-6].