A study of the grid dependence of the flow field and noise of subsonic jets
A study of the grid dependence of the flow field and noise of subsonic jets
复制标题
亚音速射流流场和噪声的网格相关性研究
DOI：
10.2514/6.2016-0261
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发表时间：
2016
影响因子：
2.6
通讯作者：
O. Marsden
中科院分区：
文献类型：
--
作者：
C. Bogey;O. Marsden
采用大涡模拟方法计算了马赫数为0.9、直径雷诺数为10的三个等温圆射流，采用三种分辨率递增的网格，研究了射流流场和噪声的网格依赖性。射流对应于两个初始完全层流射流和一个初始强烈扰动射流在以前的数值研究中考虑。在半径为r0的喷管出口处，z = 0时，它们表现出厚度为0.2r0、0.025r0和0.15r0的层流边界层平均速度剖面，峰值湍流强度分别接近0.2%、0.3%和9%。网格包含多达10亿个点，与以前的研究中使用的网格相比，它们在轴向（z ≥ 5r0）和径向（射流混合层外部区域）上要精细得多。通过数值模拟得到了主射流流场和噪声特性，包括混合层厚度、中心线平均速度、喷嘴唇线和射流轴线上的湍流强度、射流中的速度谱以及近场和远场压力谱。对于初始层流射流与薄边界层和初始扰动射流，显着差异被发现相对于以前的研究结果。喷流发展更快，由于更强的大尺度结构的存在，势核端部的上游和下游的湍流强度更高，并且产生更多的低频噪声。然而，对于三个射流，使用本网格得到的结果是非常相似的。
Three isothermal round jets at a Mach number of 0.9 and a diameter-based Reynolds number of 10 are computed by large-eddy simulation using three grids with increasing resolution in order to investigate the grid dependence of the jet flow field and noise. The jets correspond to two initially fully laminar jets and one initially strongly disturbed jet considered in previous numerical studies. At the exit of a pipe nozzle of radius r0, at z = 0, they exhibit laminar boundary-layer mean-velocity profiles of thickness 0.2r0, 0.025r0 and 0.15r0, and peak turbulence intensities close to 0.2%, 0.3% and 9%, respectively. The grids contain up to one billion points, and, compared to the grids used in previous studies, they are much finer in the axial direction for z ≥ 5r0, and in the radial direction in the outer region of the jet mixing layers. The main jet flow field and noise characteristics given by the simulations, including the mixing-layer thickness, the centerline mean velocity, the turbulence intensities on the nozzle lip line and the jet axis, velocity spectra in the jets, and near-field and far-field pressure spectra, are presented. For the initially laminar jet with thin boundary layers and the initially disturbed jet, significant differences are found with respect to the results from previous studies. The jet development is more rapid, the turbulence intensities just upstream and downstream of the end of the potential core are higher due to the presence of stronger large-scale structures, and more low-frequency noise is generated. For the three jets, however, the results obtained using the present grids are very similar.