Lambda shock behaviors of elliptic supersonic jets; a numerical analysis with modification of RANS turbulence model
Lambda shock behaviors of elliptic supersonic jets; a numerical analysis with modification of RANS turbulence model
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DOI：
10.1016/j.ast.2021.106613
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发表时间：
2021-02
影响因子：
5.6
通讯作者：
S. A. Mirjalily
中科院分区：
文献类型：
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作者：
S. A. Mirjalily
超音速喷气发动机在不同行业有着广泛的应用，特别是作为吸气式发动机和超音速喷射器的推进器。本文对不同展宽比和不同收敛段与扩张段长度比(称为几何比)的椭圆喷管出口流动进行了三维数值研究，并研究了突片对超音速射流出口流动行为的影响。在这方面，OpenFoam软件与粉刺算法一起使用。首先利用实验数据对k-ω海温湍流模型的系数进行了修正，然后对所提出的方法进行了验证。结果表明，β⁎为0.075是预测射流出口流动行为的最佳状态。然后，应用改进的湍流模型研究了展弦比(超音速射流出口的长短比)为2.5、3和4，几何比为1.672、1.106、0.738、0.48和0.2878，以及三角形、正方形和半圆形突片对超音速射流出口流动行为的影响。通过改变上述比例，对于分流部分斜率的变化，影响了流动分离区，改变了边界层-激波干扰。此外，结果还表明，激波结构的改变，进而导致输出能量的耗散是不可避免的。
Supersonic jets have various applications in different industries, particularly as the propulsion of air-breathing engines and supersonic ejectors. The present study aimed to carry out a 3D numerical investigation of the outlet flow of elliptic nozzles of different aspect ratios and different length ratios of the convergent to the divergent part (called geometric ratio), as well as addressing the effect of tabs on the behavior of the outlet flow of the supersonic jet. In this regard, OpenFoam software was used alongside the pimple algorithm. First, the coefficients of the k-ω SST turbulence model were modified using experimental data, followed by the validation of the proposed method. The obtained results showed that β⁎ of 0.075 led to the best state of predicting the behavior of the jet outlet flow. Then, the modified turbulence model was applied to investigate the effect of aspect ratios (the ratio of the major to the minor length of the supersonic jet outlet) of 2.5, 3, and 4, geometric ratios of 1.672, 1.106, 0.738, 0.48, and 0.2878, and triangular, square, and semi-circular tabs on the behavior of the outlet flow of the supersonic jet. By changing the above ratios, regarding the change in the slope of the divergent part, the flow separation region was affected, and the boundary layer-shock wave interaction altered. Further, the results indicated a change in the structure of shock waves and, in turn, dissipation of the output energy was inevitable.