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

点击翻译按钮获取中文摘要

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.