高度欠膨胀声速射流的自相似特性

发布时间：2018-05-16 13:00

本文选题：高度欠膨胀射流 + 大涡模拟　；参考：《航空动力学报》2017年01期

【摘要】：构建了高压气体射流模型和高分辨率的计算网格,对喷压比(NPR)为5.60、流动雷诺数Re为105量级的高度欠膨胀射流进行了三维大涡模拟(LES)计算.讨论了时均的射流近场结构,发现大涡模拟成功捕捉到了高度欠膨胀射流近场的典型波系结构,并与文献结果吻合较好.研究着重定量考察流向速度和氮气质量分数的分布规律,以揭示高度欠膨胀射流的自相似特性.结果表明:在射流核心区之后,不同流向位置上流向速度和氮气质量分数沿径向的分布呈现出与亚声速射流类似的自相似特性.但射流流场开始呈现自相似的位置仍然为超声速,这是高度欠膨胀射流自相似特性的独有特征.提出了高斯拟合公式,在靠近和远离射流中心线的区域内均可较好地表征射流的自相似特性.此外,还考察了射流剪切层的发展特征,比较了计算得到的射流剪切层增长率与先前实验测量结果的差异,并分析了其中可能的原因.
[Abstract]:A high pressure gas jet model and a high resolution computational grid were constructed. The 3-D large eddy simulation (les) was performed for a high altitude underexpansion jet with a jet pressure ratio of 5.60 and a Reynolds number of 105. The near field structure of time averaged jet is discussed. It is found that the large eddy simulation has successfully captured the typical wave system structure of the high underexpansion jet near field, and the results are in good agreement with the results in the literature. The distribution of flow velocity and nitrogen mass fraction was investigated quantitatively in order to reveal the self-similarity of highly underexpansion jet. The results show that the radial distribution of flow velocity and nitrogen mass fraction at different flow direction positions is similar to that of subsonic jet after the core region of the jet. However, the self-similar position of the jet flow field is still supersonic, which is the unique feature of the self-similar characteristics of the highly underexpansion jet. The Gao Si fitting formula is presented, which can well characterize the self-similar characteristics of the jet in the region near or away from the central line of the jet. In addition, the development characteristics of jet shear layer are investigated, and the difference between the calculated jet shear layer growth rate and previous experimental results is compared, and the possible causes are analyzed.
【作者单位】：中国科学院力学研究所高温气体动力学国家重点实验室;中国科学院大学工程科学学院;
【基金】：国家自然科学基金(11502270) 中国博士后科学基金(2016M591258)
【分类号】：O358

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