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- 2018
二次流引射对保形非对称喷管性能的影响Abstract: 发动机与飞机后体结构设计合理与否直接影响发动机的部件匹配和性能。利用三维雷诺平均N S方程和k-ω SST湍流模型对飞翼布局无人机保形非对称喷管在典型飞行状态下开展了内外流流场特性的数值分析,获得了后体尾喷管推力性能和三维流动特征随二次流压力比的变化趋势。结果表明:发动机喷管落压比条件一定的前提下,通过合理优化二次流通道、增大二次流压力比,可以有效改善后体/喷管主流流场特性;当二次流与主流的流量比在0.2%~1.86%内时,后体尾喷管轴向推力系数的变化幅度大约为3%,在一定程度上能够减弱发动机主流的过膨胀程度,减小发动机推力损失,无人机后体尾喷管性能得到显著提高。The reasonability of the structure design of aircraft engine and after-body directly affects the components matching and performance of the engine. The numerical analysis for the internal and external field characteristics of the conformal asymmetric nozzle of flying-wing unmanned aerial vehicle in the typical flight condition was carried out by adopting the 3D Reynolds-averaged N-S equation and k-ωSST turbulence model. The thrust performance of after body nozzle and also the variation trend of the 3D flow characteristics against the blow-down ratio of secondary flow were obtained. The results show that under a fixed blow-down ratio of the engine nozzle, the main flow field characteristics of the after-body nozzle can be effectively improved by reasonably optimizing the secondary flow channel and increasing the blow-down ratio of secondary flow;when the flow rate of secondary flow and main flow is within the range of 0.2% to 1.86%, the changing range of nozzle axial thrust coefficient is about 3%. Overexpansion of the engine′s main flow is weakened to a certain extent and thrust loss of the engine is decreased. Therefore, the blow-down ratio of secondary flow has great influence on the performance of the after-body nozzle of unmanned aerial vehicle.
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