Experimental investigation of single expansion ramp performance

Abstract

The performance, in terms of thrust augmentation, of a single expansion ramp nozzle (SERN), attached at the exit of a half-covergent-divergent (C-D) nozzle, was investigated experimentally. The nozzle exit Mach number tested was 1.7. The ramp exit was designed for a theoretical Mach number 3.5, based on inviscid theory. Pressure measurements all along the centerline of the ramp plate, with and without side fence, were carried out for half-nozzle operating pressure ratios of 3 to 8. In addition to the pressure measurement, the flow over the ramp plate was visualized with shadowgraph and surface coating. Results show that the thrust augmentation obtained is much lower than the inviscid theoretical prediction. This is because of the flow separation over the ramp and the associated curved shock formed downstream of separation bubble.