冲压发动机点火性能影响因素研究

An Investigation on Effects of Several Factors on the Ignition Characteristics in a Ramjet Combustor

为了考察来流参数对冲压发动机高空点火性能的影响,采用基于最小点火能量的分析方法,对亚燃冲压发动机高空直连式试验结果进行了分析。研究结果表明,燃烧室内来流参数的变化对点火性能具有较大的影响。温度升高导致最小点火能量迅速减小,其主要原因在于火焰传播速度随温度升高的逐渐增加。燃烧室内气流速度的增加导致最小点火能量的急剧增加,其中湍流脉动速度的增加导致了核心火团热量散失的增加,是导致最小点火能量增加的最主要因素。当密度增加时,燃烧室内的最小点火能量会大幅度的增加,其中燃料液雾的SMD的减小是点火能量增加的次要因素,而密度降低引起了化学反应速率降低,化学反应时间的增加则是其中的主要因素。

In order to investigate the effects of several factors on the ignition characteristics in a ramjet, minimum ignition energy analysis method was conducted with a result from ground direct-connect test com- bustor. The results show that the increase of temperature results in the increase of flame speed and a sharp decrease of minimum ignition energy. Further, the minimum ignition energy increases with the increase of flow speed which causes the enhancement of turbulent velocity, and leads to the increasing of heat loss in the combustor. Also, the minimum ignition energy increases with the decrease of density, because the en- largement of chemical reaction time and decreasing of reaction rate play more important roles on the mini- mum ignition energy, rather than the enlargement of SMD of spray in lower density conditions.