针对关于卫星推进器尾焰的红外特性研究较少的现状，对某双组元轨控推进器尾焰的红外辐射进行数值模拟。采用贴体坐标系下的有限体积法，联合求解较复杂形状的喷管扩张段和尾焰的辐射传递方程，得到尾焰的光谱和3～5 μm的波段辐射强度。为精确计算尾焰的红外辐射，全面评估了喷管扩张段的辐射对后端尾焰红外辐射的影响。通过对比分析，当天顶角θ＝7π/16时，距离喷口的位置越近，尾焰辐射受到扩张段的影响越剧烈；若扩张段内壁的发射率减小，尾焰在θ＝7π/16方向上的波段辐射强度则会变小；喷口近处的尾焰，在扩张段辐射影响下，计算得到的波段辐射强度数值远大于忽略扩张段的影响下得到的数值。得出结论：在考虑喷管扩张段辐射的影响下，能够很好地改善轨控推进器尾焰红外辐射的计算准确性。

As lacking study on satellite thruster plume infrared characteristics, the infrared radiation of a bi-propellant orbit thruster plume were numerical simulated. The radiative transfer equations of the plume and the relatively complex shape nozzle expanding segment were solved simultaneously by using the Finite Volume Method in body-fitted coordinate. The plume radiation spectral and 3～5 μm band radiative intensity were obtained. In order to accurately calculate the plume infrared radiation, how the nozzle exiting section radiation influenced the plume radiative intensity was evaluated. Through comparison and analysis, we found that, when the distance between the plume and the nozzle exiting section get close, the plume radiation at θ＝7π/16 will be affected by the nozzle expanding more and more; when the emissivity of the inside nozzle wall is reduced, the plume band radiative intensity at θ＝7π/16 will decrease; near to the nozzle exiting section, the plume band radiative intensity value influenced by the nozzle expanding is far lager than the value taking no account of the influence. It is concluded that the calculation accuracy of the orbit thruster plume infrared radiation is improved when taking account of the influence from the nozzle expanding segment.