化学反应机理对液氧煤油发动机尾焰红外特性影响研究

提出了一种液氧煤油发动机尾焰红外辐射特性计算方法，首先采用计算流体力学软件对液氧煤油发动机内流场进行计算，然后以获得喷管喉部截面参数作为入口边界条件计算发动机尾焰流场，最后以发动机尾焰流场参数分布为基础，采用有限体积法对发动机尾焰红外光谱辐射特性和成像特性进行计算，并对比验证了模型和方法的准确性。在此基础上，研究了化学反应机理和复燃反应过程对尾焰红外辐射特性影响。结果表明，采用多步化学反应能够准确模拟液氧煤油发动机内流场，温度相比热力学计算大3.34%，压力相比试车测量大2.89%；考虑复燃反应使尾焰红外辐射强度增强显著，在采用单步化学反应和多步化学反应两种工况下2~5波段红外辐射强度分别增大50%~100%和150%~170%，但不会影响尾焰红外光谱辐射特性和红外总辐射强度随探测角变化趋势；采用单步化学反应和多步化学反应都能够获得清晰结构的红外成像图像，但是前者2~5尾焰红外辐射强度要比后者增大90%~190%，且两种工况下发动机尾焰红外光谱辐射特性差别很大，尾焰红外总辐射强度随探测角变化趋势也不同。

Study on the Influence of Chemical Reaction Mechanisms on the Infrared Radiation Characteristics of the LOX/Kerosene Rocket Engine Plume

In this paper, a method to calculate the LOX/kerosene rocket engine plume infrared radiation characteristics is proposed. First of all, the simulation of engine internal flow field is carried out, and the nozzle throat section parameters are obtained as the inlet boundary condition. Then the calculation of single nozzle and multi-nozzle engine exhaust plume flow field are carried out, infrared spectral radiation characteristics and radiation imaging characteristics of the engine plume are calculated with the finite volume method (FVM) based on the field parameters. The accuracy of the method and the model are proved. On this basis, studies on the influence of chemical mechanisms and the reaction on the plume infrared radiation characteristics are carried out. It is found that the internal combustion field of the LOX/kerosene engine are simulated accurately with the multi-step chemical reaction model, the temperature is 3.34% higher than that from the thermodynamics calculation and the pressure is 2.89% greater than that from the engine test result. The reaction can enhance the infrared radiation of the plume, and the increase ratio in the 2~5 μm band of the two condition of the single-step chemical reaction and the multi-step chemical reaction achieve 50%~100% and 150%~170%, but it can’t affect the infrared spectral radiation characteristics and the variation trend of infrared total radiation intensity with detection angle. The clear infrared images are obtained with both the single-step chemical reaction and the multi-step chemical reaction, the infrared radiation intensity of the former is 90%~190% greater than that of the later, but the infrared spectral radiation characteristics and the variation trend of infrared total radiation intensity with detection angle vary widely with different chemical reactions.