采用反向蒙特卡罗法(Reverse Monte-carlo,简称RMC)结合窄带模型计算了模型涡扇发动机(不带加力)排气系统的红外辐射强度。考虑了金属壁面的发射和反射以及燃气中CO2,CO和H2O等组分的吸收、发射和透射,组分的吸收系数由NASA SP3080数据库获得,并对判断射线归宿的过程进行了改进,开发了计算程序。实验测量了模型涡扇发动机排气系统的中波红外光谱辐射强度及其空间辐射强度分布。结果表明:计算得到的3～5μm波段内的光谱辐射强度以及空间辐射强度分布与实验值吻合较好,最大误差为10%左右,本文的计算方法能比较准确地反映涡扇发动机排气系统在非加力状态下的中波红外辐射特征。

Reverse Monte-Carlo method(RMC) combined with narrow band model is adopted to calculate the infrared characteristics of a turbofan engine exhaust system model without afterburning.The processes of emission and reflection of metal surfaces,and the processes of emission,absorption and transmission of CO2、CO and H2O in gas are considered,and the absorption coefficients of the species are obtained from NASA SP3080 database.The method of searching the absorption location is improved,and the relevant computer code is developed.The distributions of spectral and spatial infrared radiation intensity of the exhaust system model are measured.The results show that the computed spatial and spectral infrared radiation intensity in 3~5μm waveband agrees with the experimental data quite well,and the maximum error is about 10%.The numerical method of this paper could accurately calculate infrared radiation intensity of 3~5μm waveband of turbofan engine exhaust system without afterburning.

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