Numerical investigation on the infrared signature of shock vector controlling nozzle

The exhaust system is the main source that contributing to the total aircraft infrared signature. This paper analyses the infrared signature of shock vector controlling nozzle. Firstly, the contributions of different parts of the nozzle to the total infrared signature were discussed. The discussion shows that the core flow inlet has a marked influence on the total infrared radiation intensity when the azimuth angle of probe point is small. And the infrared radiation from the bypass flow inlet is small enough to be negligible. Then, the influences of the secondary flow and the injection position of the secondary flow on the infrared signature of shock vector controlling nozzle were investigated. The results demonstrate that the secondary flow can reduce the infrared signature significantly when the azimuth angle of probe point is large. The maximum relative reductions are 60.8% and 51.3% for probe points lying in the horizontal plane and the vertical plane, respectively. The injection position of secondary flow has a marked effect on the core length, and then affects the infrared signature at large azimuth angle.