Numerical investigation on thrust characteristics of an annular expansion–deflection nozzle
Numerical investigation on thrust characteristics of an annular expansion–deflection nozzle
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DOI：
10.1063/5.0150129
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发表时间：
2023-05
影响因子：
4.6
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中科院分区：
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基于详细的流型模拟，研究了大膨胀比环形膨胀偏转（ED）喷嘴的推力特性。目的是在喷管内部流型和喷管推力性能之间架起一座桥梁。本工作沿着典型流线追踪流动参数以展示喷管流型，根据喷管出口平面的流动特征对喷管出口平面进行划分，以评估不同分区中每个推力系数贡献者的推力贡献，并监测22种喷管压力比下喷管出口平面的流动参数分布，以解释喷管推力系数的发展历史。目前的模拟表明，开放尾流模式中产生的冲击是不可避免且不可或缺的，而封闭尾流模式中产生的冲击对推力性能产生负面影响。明确了设计高性能ED喷管的三个基本要求，即确保喷管喉部的高质量膨胀、平滑开放尾流模式下的反射激波以及减弱封闭尾流模式下产生的强烈近壁激波。解释了一个有趣且反直觉的现象，即开尾流模式下反射激波的存在不仅消耗了排气流做功的能力，而且提高了喷管的整体推力性能。这是因为反射的冲击使横向排气流偏转至轴向方向。当反射冲击消失时，喷嘴推力系数历史会突然下降。
The thrust characteristics of a large-expansion-ratio annular expansion–deflection (ED) nozzle are investigated based on detailed flow pattern simulations. The purpose is to build a bridge between the nozzle internal flow pattern and nozzle thrust performance. The present work traces flow parameters along typical streamlines to demonstrate the nozzle flow pattern, partitions the nozzle exit plane based on its flow features to evaluate thrust contributions of each thrust coefficient contributor in different sub-areas, and monitors flow parameter distributions in the nozzle exit plane at 22 nozzle pressure ratios to interpret the developing histories of nozzle thrust coefficients. The present simulations show that the shocks generated in open wake mode are both inevitable and indispensable, while the shocks generated in closed wake mode contribute negatively to thrust performance. Three basic requests for designing a high-performance ED nozzle are clarified, which are to ensure high-quality expansion at the nozzle throat, to smooth out the reflected shock in open wake mode, and to diminish the strong near-wall shock generated in closed wake mode. An interesting and counter-intuitive phenomenon, namely, the existence of the reflected shock in open wake mode not only consumes the ability of the exhaust flow to do work but also improves the overall nozzle thrust performance, is explained. This is because the reflected shock deflects lateral-going exhaust flow to the axial direction. When this reflected shock disappears, a sudden drop in the nozzle thrust coefficient history takes place.