Accurate Numerical Solution of Infrared Radiation Signature from Aircraft Plume

The temperature of aircraft plume varies greatly due to the large amount of high-temperature gas generated by the aeroengine. At present, the narrowband models are widely used to calculate the infrared radiation signature of the aircraft plume. However, the classical narrowband models make large errors when applied to the gas with large thermal gradient. To improve the accuracy of calculation, the classical Malkmus narrowband model was extended based on the idea of fictitious gas. The radiation characteristic parameters of H2O,CO2, and CO2-H2O-N-2 mixture at different temperatures were calculated using the classical Malkmus narrowband model and the extended model, respectively. Compared with the classical Malkmus narrowband model, the calculated results of the extended model are obviously in better agreement with the measured data. Based on the extended Malkmus narrowband model, a line-of-sight method was used to calculate the infrared radiation signature of aircraft plume. And the infrared radiation intensity of the plume of a scaled aeroengine nozzle was calculated. The results showed that the relative error between the calculated intensity and the measured data is -2.41%.