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为了研究横向射流注入后飞机发动机排气系统红外辐射的变化情况,设计了不同横向射流注入方案。实验探测了在喷口处注入横向射流后,排气系统在水平探测面上,3~5μm波段内的红外辐射强度。分析了排气系统的光谱辐射强度和积分辐射强度的变化情况,并结合速度分布图及红外热像图给出了解释。由于射流能够挤压尾喷流,提高主流剪切层脉动强度,强化其与冷气流的掺混,不同方案横向射流的注入,均能引起排气系统红外辐射强度的降低;在同一个探测面上,探测器能探测的红外辐射强度因不同射流方案对尾喷流的挤压方向不同而有较大差异,探测到的红外辐射由强到弱的方案依次:垂直注入、周向四股注入和水平注入;对尾喷流而言,相比于无横向射流注入状态,采用横向射流双股、单股垂直注入时,其红外辐射强度分别下降了60%,45%;横向射流双股、单股水平注入时,分别下降了5.1%,5.3%;采用周向四股注入时,下降了24.7%。
In order to study the variation of infrared radiation of aircraft engine exhaust system after lateral jet injection, different lateral jet injection schemes were designed. The experiment explored the infrared radiation intensity in the 3 ~ 5μm band on the level detection surface of the exhaust system after injecting the transverse jet at the nozzle. The changes of the spectral radiation intensity and the integral radiation intensity of the exhaust system are analyzed, and the explanation is given based on the velocity distribution map and the infrared thermogram. Because the jet can squeeze the tail jet, improve the pulsating strength of the mainstream shear layer and strengthen its mixing with the cold air flow, the injection of the transverse jet of different schemes can cause the decrease of the infrared radiation intensity of the exhaust system. In the same detection plane , The intensity of the infrared radiation detected by the detector is greatly different due to different squeezing directions of the jet flow to the tail jet flow. The schemes of detecting the infrared radiation from strong to weak are in turn: vertical injection, Compared with the state of no transverse jet injection, the lateral jet jet has a 60% and 45% reduction in the intensity of infrared radiation when using double-jet and single-jet vertical injection, respectively. Unit level injection, respectively, down 5.1%, 5.3%; use of circumferential injection of four strands, down 24.7%.