多股流 S 弯喷管红外辐射特性研究

A numerical simulation was carried out to investigate the spatial distribution characteristics of infrared radiation intensity of a multi-stream serpentine nozzle for an adaptive engine under both design and off-design conditions. The underlying mechanisms and influencing factors of the IR radiation characteristics were comprehensively analyzed. The results revealed that under design conditions，the curvature of the mainstream shape caused a hot spot to form on the upper wall of the nozzle outlet，resulting in the wall infrared radiation intensity accounting for up to 54% of the total radiation at a negative detection angle on the vertical plane. The gas infrared radiation intensity was identified as the main source of radiation at other angles，and the gas radiation intensity within the nozzle was significantly higher than that of the plume radiation intensity. Under off-design conditions， the wall infrared radiation intensity remained relatively constant. An increase in the pressure ratio led to changes in the internal gas pressure and exit shock waves shape of the nozzle，resulting in an enhanced gas infrared radiation intensity within the nozzle， and a weakened plume infrared radiation intensity. The gas infrared radiation intensity was jointly affected by internal gas and plume radiations.