Influence of emissivity on infrared radiation characteristics of the two-dimensional nozzle

Abstract

In the case of the same outlet area, the two-dimensional (2-D) nozzle has a large aspect ratio compared to the axisymmetric circline nozzle, which enables it to reduce the visible area of high-temperature components such as the center cone and the flame stabilizer inside the nozzle. It can also strengthen the mixing effect of wake flow and outflow to achieve the effect of cooling. In this work, based on the calculation of the flow field of the 2-D convergent-divergent nozzle, the infrared radiation characteristics of its with different emissivity coatings and the coating under high-temperature coming off are calculated in the 3∼5um waveband. The results show that with the increase of emissivity, the mean value of infrared radiation intensity of the nozzle in the range of detection angle 0°-70° decreases to 68.80%, while the mean value of infrared radiation intensity in the range of detection angle 80°-90° rises to 136.55%. The nozzle coating coming off is caused by excessive temperature and its infrared radiation intensity even exceeds the infrared radiation intensity of the uncoated state when the coating comes off.