面向飞/发一体化设计的高温尾喷口流场分析

Analysis of high temperature nozzle exhaust flow towards aircraft-engine integrated design

结合飞/发一体化设计理念,以提升红外隐身性能为目的,引入横向掺混技术进行尾喷管构型设计。应用计算流体力学(CFD)数值仿真方法,分别分析了圆形喷管和矩形喷管流场温度分布,并提取矩形喷管中心面,研究喷管带小孔壁板偏折角对尾流冷却效果的影响。研究结果表明:相对于入口热流温度,矩形喷口降温率约为30%,尾气流喷出后偏向两侧流动,高温核心区体积快速衰减;圆形喷口降温率约为10%,尾气流喷出后沿轴向一直保持圆柱形,高温核心区体积衰减缓慢。矩形喷口主动冷却效果明显高于圆形喷口,更有利于实现飞/发一体化的热管理及红外隐身。同时,中面带小孔壁板偏折角的大小与主动冷却效果也存在密切关系。

Combined with the aircraft-engine integration concept, transverse jet mixing technology is introduced to conduct the nozzle design in order to improve infrared stealth performance. The temperature field of circular and rectangular nozzle exhaust flow is analyzed by computational fluid dynamics （CFD） numerical simulation method, and we extract the central face of the rectangular nozzle to observe the cooling effect of transverse jet walls along with different angles. The results show that compared with the inlet temperature, the cooling ratio of rectangular nozzle reaches 30% approximately, the ex- haust plume flows to both sides, and the volume of the core high temperature flow decreases obviously; circular nozzle cool- ing rate is about 10% ,the exhaust plume keeps cylindrical along the central line, and the core jet volume attenuation is slow. Consequently, the rectangular nozzle cooling efficiency is significantly higher than that of the circular nozzle and is more ad- vantageous to realize aircraft-engine integrated thermal management as well as infrared stealth. Additionally, active cooling effect also has close relationship with the deflection angle magnitude of the mid wall with transverse jet.