NOx Formation Mechanism in engines of next generation aircraft and Effects of Emission of NOx on Global Atmosphere

对25 km高空平流层飞行排气羽流对臭氧的消耗进行了数值分析。采用膨胀箱法模拟了平流层烟气羽流的扩散过程。用五阶BDF法估计了化学物质的浓度和臭氧浓度对反应的归一化敏感性。化学动力学包括NOx， Hex和Ox化学。结果是，羽流中的臭氧浓度需要两天才能达到1 ppb以内的环境水平。臭氧扰动受羽流发射时间的影响而改变，且白天比夜间更大。臭氧浓度对反应的敏感性分布也随羽流排放时间的变化而变化。在废气羽流中，氮氧化物对臭氧的消耗大于HOx。为了研究液体煤油在超燃冲压发动机燃烧室中的燃烧方式和着火极限，进行了液体煤油在超燃冲压发动机燃烧室中的燃烧实验研究。使用了三个燃烧器，它们都有一个后台阶，其中一个有一个空腔，可以在台阶的上游注入气态氢。在2.0马赫的高焓气流中正常喷射煤油，用CCD相机观察煤油的喷射和燃烧过程。根据燃烧室顶壁上的静压分布来判断燃烧模式。因此，在超声速气流中，雾化行为对液体燃料的点火起着重要的作用。在任何主流总温度下，喷油器内径为0.3 mm时均未发生点火和稳定燃烧。喷油器内径为0.5 mm时，在主流总温度2300K以上发生点火。

Numerical analysis of ozone depletions by exhaust plume from stratospheric flight at the altitude of 25 km was conducted. Expanding box method was employed to simulate a diffusion of exhaust plume in the stratosphere. Concentrations of chemical species and normalized sensitivities of ozone concentration for reactions were estimated by fifth-order BDF method. Chemical kinetics include NOx, Hex and Ox chemistry. As results, it takes over two days that ozone concentration within a plume becomes ambient level within 1 ppb. Ozone perturbations were changed by an effect of plume-emission time, and they are bigger in daytime than in nighttime. Distributions of sensitivities of ozone concentrations for reactions are also changed for plume-emission time. Ozone depletion is greater by NOx than HOx in an exhaust plume.An experimental research on combustion of liquid kerosene in a scramjet combustor was conducted in order to investigate combustion modes and ignition limits. Three combustors, which had a backward step, were used, and one of these had a cavity and could inject gaseous hydrogen at the upstream of the step. Kerosene was injected normally into a Mach 2.0 high-enthalpy airflow, and the injection and combustion of kerosene were observed by a CCD camera. Combustion modes were judged from a distribution of static pressure on the top wall of the combustor. As a result, atomization behavior is an important role for the ignition of liquid fuel in a supersonic air flow. The ignition and stable combustion is not observed when the inner diameter of fuel injector is 0.3 mm for any total temperatures of the main flow. The ignition occurs for above 2300K of the total temperature of the main flow when the inner diameter of the fuel injector is 0.5 mm.