The aeroacoustics of slowly diverging supersonic jets
The aeroacoustics of slowly diverging supersonic jets
复制标题
缓慢发散的超音速喷气机的气动声学
DOI：
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发表时间：
2008
影响因子：
3.7
通讯作者：
S. J. Leib
中科院分区：
文献类型：
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作者：
M. Goldstein;S. J. Leib
本文利用声学类比法来预测未加热超声速喷流的声音。以前的尝试在实际感兴趣的马赫数范围内进行这种预测是不成功的。因此，本文件的重点是落实实现这一目标所需的改进措施。影响峰值超声速噪声的重要因素是源对流，平均流折射，平均流放大，和源的非紧凑性。后两种效应在文献中似乎没有得到充分的处理。对于第一种情况，这是因为通常的平行流模型在所谓的临界层中产生大部分放大，在临界层中，解变得奇异，因此导致预测的声场变得无限大。我们通过引入一个新的弱非平行流分析，消除了临界层奇异性来处理这个问题。这对峰值噪声频谱的形状有很大影响。最后一个效应对较高马赫数下的声源模型提出了严格的要求，因为在这种情况下，延迟时间变化显著地增加了辐射声对声源结构的灵敏度。因此，本文介绍了一种高度精细（不可分离）的源模型。
This paper is concerned with utilizing the acoustic analogy approach to predict the sound from unheated supersonic jets. Previous attempts have been unsuccessful at making such predictions over the Mach number range of practical interest. The present paper, therefore, focuses on implementing the refinements needed to accomplish this objective. The important effects influencing peak supersonic noise are found to be source convection, mean flow refraction, mean flow amplification, and source non-compactness. It appears that the last two effects have not been adequately dealt with in the literature. For the first of these this is because the usual parallel flow models produce most of the amplification in the so-called critical layer where the solution becomes singular and, therefore, causes the predicted sound field to become infinite. We deal with this by introducing a new weakly non-parallel flow analysis that eliminates the critical layer singularity. This has a strong effect on the shape of the peak noise spectrum. The last effect places severe demands on the source models at the higher Mach numbers because the retarded-time variations significantly increase the sensitivity of the radiated sound to the source structure in this case. A highly refined (non-separable) source model is, therefore, introduced in this paper.