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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。
Aiming at the under-swirling supersonic jet acoustic radiation characteristics with a Mach number of 1.95, a numerical simulation is carried out using a large-eddy simulation (LES) method with a high precision calculation format. The accuracy of the numerical method is confirmed by comparing the statistical results of jet flow and turbulent flow. The flow characteristics of supersonic jet flow are analyzed in detail, with particular attention paid to the interaction between shock cell and turbulent flow. Based on the correlation between the flow and the sound field radiation, the characteristics of the noise radiation and the formation mechanism of supersonic jet Mahbo and broadband shock wave are analyzed. The numerical results show that the shear layer evolution of supersonic jet and the interaction between shock cell and turbulence constitute the main source of noise for the under-inflated supersonic jet.