马赫数1.95超声速欠膨胀喷流声辐射数值分析

针对马赫数为1.95的欠膨胀超声速喷流声辐射特性，采用高精度计算格式的大涡模拟（LES）方法进行数值研究。通过对喷流平均流及湍流脉动统计结果的对比，确定数值方法的精确性。细致分析了超声速喷流流动特征，特别关注了其中激波胞格和湍流相互作用现象。基于流动与声场辐射间的关联性，分析了超声速喷流马赫波、宽频激波噪声辐射特性及形成机理。数值结果表明超声速喷流的剪切层演化及激波胞格与湍流间的相互作用构成欠膨胀超声速喷流的主要噪声源。

Numerical investigation of acoustic radiation from Mach number 1.95 supersonic underexpanded jet

Acoustic radiation from a supersonic underexpanded jet with a designed exit Mach number 1.95 is investigated using large eddy simulation (LES). By comparing the statistical results of the mean flow and the turbulence fluctuation of the jet, we verify the accuracy of the numerical method. We carry out a detailed analysis of the flow characteristic of the supersonic jet flow, and pay particular attention to the interaction between shock-cell and turbulence. According to the correlation between jet dynamic and its acoustic field, the features and generation mechanisms of Mach wave radiation and broad band shock associated noise from the jet are carefully analyzed. Numerical results show the shear layer dynamic evolution and the interaction between shock-cell and turbulence constitute the major noise sources of the supersonic underexpanded jet.