Effect of riblets on the performance of a supersonic nozzle

This paper describes the experimental study of the supersonic internal flow over the riblet surface mounted on the channel wall to reduce a pressure loss and improve the performance of a supersonic nozzle. The magnitude of the static pressure in the pressure-rise region observed in channels with riblet surface became lower than that for the case of smooth surface, and significance of its difference was indicated by uncertainty analysis estimated at 95% coverage. The Mach number distributions obtained by traversing a Pitot-tube showed that the separation point moved downstream and the size of a separation region became small by using riblets. Furthermore, it was found that the stagnation pressure loss reduction achieved up to 56% in the uniform supersonic flow field at a Mach number of 2.0, and 29% in the separation region.