总焓模拟含水实验介质对双模态燃烧室过程与性能的影响分析

Analysis of Water-Vitiated Medium Effects on Dual-Mode Combustor Process for Enthalpy-Simulated Method

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

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

摘要:

为评估燃烧加热设备对冲压发动机地面结果的影响，采用经典准一维方法，考虑燃烧可能存在的化学平衡过程，结合所发展的工作过程物理模型，研究了地面模拟飞行马赫数4～7实验中、氢气-空气加热器采用总焓模拟标准时，含水实验介质对发动机释热与面积匹配、性能潜力的影响规律。结果表明，在模拟总焓条件下，使用略大的燃烧室，燃料比冲数据和纯空气条件较为接近，Ma4～6条件下偏差不超过±1%，Ma7时不超过+3.1%，最大比冲对应的特征马赫数也和纯空气条件相同；但燃烧室所需扩张比、燃烧效率、空气比冲均大于纯空气条件，其中Ma4～7时空气比冲的最大偏差分别达到+2.2%，+4.5%，+8.3%，+14.4%，燃烧效率的偏差分别为+0.7%，+1.9%，+4.2%，+9.4%。这些数据的巧合与矛盾说明，需要在理解实验介质影响规律的基础上，建立纯空气应用时释热工作过程的再设计能力。

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.