关键词: 冲压发动机，准一维方法，介质影响，性能与过程，总焓模拟

Abstract: To study the effects of vitiated facility on dual-mode scramjet experiment，the difference of dual-mode combustor gasdynamic process and the resulting performance in a water-vitiated test air and pure air is studied. A classical quasi-one dimensional method is used with consideration of possible chemical equilibrium process in combustion and with a self-developed dual-mode combustor gasdynamic process model. It is proposed a H2-air combustion heater provides an enthalpy-simulated test medium by considering the flight Mach number from 4 to 7. The results relate to heat release in different combustor section，the needed combustor dilatation，the possible maximum thrust and specific impulse of fuel. This study show equivalent specific impulse of fuel may be obtained under iso-enthalpy conditions with a little bigger combustors when some special gasdynamic process is realized. The disperse between the two media of fuel specific impulse is no more than 1% for flight Mach number from 4 to 6，and no more than +3.1% for flight Mach number of 7. The corresponding characteristic Mach number in the combustor may be the same for the two media. But the combustor dilatation，combustion efficiency and specific impulse of air are different from pure air condition. The disperse of air specific impulse is +2.2%，+4.5%，+8.3%，+14.4% when flight Mach number varying from 4 to 7，and the disperse of combustion efficiency is +0.7%，+1.9%，+4.2%，+9.4%，respectively. The coincidence and contradiction of the resulting performance values indicate an intense need to establish a fuel-combustor matching design ability with well understanding of test medium effect on the dual-mode ramjet performance and gasdynamic process.

Key words: Ramjet；Quasi-one dimensional method；Test medium effect；Performance and process；Total-enthalpy-simulated