Effect of Integration of Scramjet into Airframe on Engine Performance and Payload

Abstract

There are three typical configurations for integrating the scramjet into the airframe of aerospace planes. They are (1) the whole engine is on the windward ramp surface of the airframe, (2) the engine is located downstream of the forebody ramp where the surface of the airframe is parallel to the airframe axis, and (3) the inlet entrance is on the ramp surface with the following engine parts parallel to the airframe axis. To examine the effect of the integrating forms on the engine performance, several types of the inlet models were tested in a wind tunnel, and simulations of the scramjet engine and the flight of the aerospace plane were conducted. The experimental results showed that the first and the third configurations showed better mass capture. In the second configuration, the pre-compression effect was neutralized by the expansion fan from the corner of the downstream end of the ramp. All configurations showed similar levels of kinetic energy efficiencies. The simulation based on the experimental results showed that the third configuration produced the best engine thrust and the least airframe drag. On the other hand, in the second configuration, the payload became negative. Thus, it is recommended that the inlet should be located on the windward ramp surface of the vehicle to inhale the precompressed air, and the following engine components should be parallel to the airframe axis to reduce the cowl drag and to increase the thrust at the external nozzle.