Computational study on aeroacoustic fields of a transitional supersonic jet.
Computational study on aeroacoustic fields of a transitional supersonic jet.
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过渡型超音速喷气式飞机气动声场计算研究
DOI：
10.1121/10.0005313
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
K. Fujii
中科院分区：
文献类型：
--
作者：
T. Nonomura;Y. Ozawa;Yoshiaki Abe;K. Fujii
采用大涡模拟方法，对超声速自由射流在马赫数2.1和雷诺数70000时的过渡条件下的气动声场进行了计算研究。对无扰动时不同剪切层厚度的超音速过渡射流和有扰动时固定剪切层厚度的超音速过渡射流进行了计算研究，讨论了剪切层厚度和扰动对超音速过渡射流的影响。这些参数对过渡的位置和过渡附近的湍流强度有明显的影响。通过减小剪切层厚度或增加扰动，可以大大减弱沿剪切层的湍流波动和由此产生的马赫波强度。观察到声压级增加了5db。与亚音速射流的10-20 dB的声压级增加相比，这种相对较低的声压级增量被认为是由于超音速射流中螺旋模态促进的过渡过程，而不像亚音速射流中轴对称的情况。通过线性稳定性分析、适当的正交分解分析和过渡区涡结构的可视化证实了这一点。
Aeroacoustic fields of a supersonic free jet at the Mach and Reynolds numbers of 2.1 and 70 000, respectively, of the transitional conditions are computationally investigated by large-eddy simulations. The supersonic transitional jets of different shear layer thicknesses without disturbances and those of the fixed shear layer thickness with disturbances are computationally investigated, and the effects of the shear layer thickness and the disturbance are discussed. The position of the transition and the turbulence intensity in the vicinity of the transition are clearly affected by those parameters. The turbulent fluctuation along the shear layer and the resulting intensity of the generated Mach waves are substantially attenuated by decreasing the shear layer thickness or adding the disturbance. A 5 dB increase in the sound pressure level is observed. This relatively lower increment in the sound pressure level compared with the 10-20 dB increase in the subsonic jet case is discussed as being due to the transition process promoted by the spiral mode in the supersonic jet case, unlike the axisymmetric case in the subsonic jet case. This point is confirmed by the linear stability analysis, the proper orthogonal decomposition analysis, and the visualization of vortex structures in the transition region.