喷管内壁多孔处理的圆口喷流大涡模拟

Large Eddy Simulation of a Round Jet From a Nozzle With Porous Inner Wall

本文对一亚音速圆口喷管内壁面施加盲孔,使其壁面多孔化,采用大涡模拟结合FW-H方法研究了马赫数M=0.6时喷管外的非稳态流场与远场噪声。研究结果显示,这种内壁小孔结构对喷管外流场的湍流脉动有一定的削弱作用。时空相关系数的对比表明,内壁小孔结构同时减弱了脉动量各自在时间和空间上的相关性,削弱了大尺度的涡结构。通过对涡强、膨胀率和Q涡识别准则的可视化分析,研究了剪切层中涡结构在喷流轴向的产生、发展与演化过程,结果表明内壁小孔结构抑制了涡配对现象,加强了流动掺混,从而加速了剪切层的发展。

In this paper, the inner wall of a subsonic nozzle is changed to be porous by adding blind holes. Large eddy simulation combined with the FW-H method are employed to study the unsteady flow field and far-field noise radiation at Mach number M=0.6. The results show that the porous wall of the nozzle has some effects on reducing the turbulence intensity. Comparisons of the turbulence correlation coefficients reveal that both the temporal and spatial correlations of the turbulent fluctuations are also suppressed by the porous inner wall. Large scale turbulence structures are weakened. The generation, development and evolution of vortices in the shear layer are studied by visualization and analysis of the vorticity, the dilatation and the Q-criterion. The results show that the pairing of vortices is suppressed and the flow mixing is enhanced by the porous wall, and as a result, the development of the shear layer is accelerated.