Some readily quantifiable aspects of scramjet engine performance

The quantitative treatment of the operation of scramjet engines is examined emphasizing the operational parameters that can be modeled and used to assess engine performance. The thermofluid dynamics of the scramjet are analyzed with consideration given to the effects of real-gas chemistry, combustion, and expansion kinetics. Modeling assumptions are described for the inlet, mixer, combustor, and nozzle flow, and results are given for different flight trajectories and Mach numbers. A combustor inlet Mach number is derived for the condition of insufficient recombination in the nozzle which maximizes Isp for flight Mach numbers over 10. The inlet Mach number is related to other operational parameters which demonstrate that the upper limit of the ratio of mass fraction to orbital speed is about 0.25. The analysis is shown to give the upper limits for performance -defined as mass ratio delivered to orbital speed - of scramjet operation. (C.C.S.)