大推力系数超声速反向射流流动结构研究

Flow Structure Analysis on High Thrust Coefficient Supersonic Opposing Jet

关键词:  反向射流  短穿透模式  流动结构  分离涡模拟  超声速流动

Key words:  Opposing jet  Shot penetration mode  Flow structure  Detached eddy simulation  Supersonic flow

摘要:

为了研究较大推力系数（C_t=4）情况下超声速反向射流的流动结构，使用分离涡模拟方法开展了超声速反向射流的数值模拟研究。以NASA Langley实验室的冷流实验为参考，选择单喷管构型进行数值模拟，并应用时均流动分析、流动结构显示等方法对流动特性进行了分析。结果表明，大推力系数情况下反向射流呈稳定的短穿透模式，射流呈现大角度锥形形状。剧烈膨胀的射流到射流激波盘处终止，并改变流动方向，形成圆锥剪切流动。圆锥剪切流动出现了K-H涡前期的流动特征，但并未观察到典型的K-H涡。通过流动显示技术观察到射流激波盘边缘处发生涡破碎现象，这是造成亚声速回流区气动扰动的重要来源。

Abstract:

Numerical simulation was carried out using detached eddy simulation（DES） method in order to research the flow structure of the supersonic opposing jet with high thrust coefficient （C_t=4）. A single nozzle configuration based on NASA Langley cold flow experiment was selected and post-process methods such as time averaging flow analysis and flow structure visualization were applied. The results show that under the condition of high thrust coefficient， the opposing jet presents a stable short penetration mode（SPM）， which presents a large-angle cone shape. The expanded jet terminates through a Mach disk（or the jet terminal shock） and reverses its orientation as a conical free mixing layer. Early K-H vortex flow characteristics appeared in the conical mixing layer but cannot observe the typical K-H vortices. Flow structure visualization techniques show vortices break up occurs at the edge of the Mach disk， which is a main source of aerodynamic disturbance in the subsonic reverse flow zone.