Comparative Analysis of Infrared Signatures of Turbofan Engine Exhaust System With or Without Afterburning

The flow fields and infrared signatures of a turbofan engine axisymmetric exhaust system with or without afterburning have been numerically investigated. The flow fields of the exhaust system have been calculated using a commercial numerical simulation software, whereas the infrared signatures have been calculated by the software nuaa-ir (numerical analysis of aircraft's infrared signature) developed by the current authors' research team. The spectral and integral radiation intensity in the waveband of 3-5 & mu;m of the axisymmetric exhaust system have been calculated and analyzed. The results show that the thrust of the axisymmetric exhaust system with afterburning is increased by 55% as compared with nonafterburning. The main infrared radiation source of the exhaust system with afterburning is the plume. The infrared radiation of the plume accounts for 65% of the total infrared radiation of the exhaust system in the downstream axial direction. The maximum integral radiation intensity of the exhaust system with afterburning is nearly seventeen times that of without afterburning. The integral radiation intensity of the exhaust system in the downstream axial direction with afterburning is about four times that of without afterburning. The integral radiation intensity of the exhaust system in the lateral direction is about 54 times higher than that without afterburning.