The role of coherent structures in the generation of noise for subsonic jets
The role of coherent structures in the generation of noise for subsonic jets
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相干结构在亚音速喷气机噪声产生中的作用
DOI：
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发表时间：
1982
期刊：
影响因子：
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通讯作者：
G. Morrison
中科院分区：
文献类型：
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作者：
G. Morrison
研究了大气压下高雷诺数（184，000 ~ 262，000）、马赫数0.6 ~ 0.8轴对称冷空气射流的拟序结构。测量了平均流量和统计时均湍流特性。频谱显示了一个非常宽的频率内容，随着流动向下游推进，该频率向较低频率移动。轴向波数测量表明，在马赫数（0.3 ~ 2.5）和雷诺数（3，700 ~ 200，000以上）的宽范围内，轴向波数-频率关系是相同的。方位角模数的测量表明，从n = -3到+3的几个模式同时存在，在不同的频率研究的各种数量。在马赫数0.6的喷流近场进行了声学测量。声压级等值线显示，噪声似乎是从潜在核心末端附近的位置辐射的。方向性图显示，这种噪音的频谱移向更高的频率，从射流轴的角度增加。还发现，中频带激励频率产生全谱噪声的增加。
The coherent structure in high Reynolds number (184,000 to 262,000), Mach number 0.6 to 0.8 axisymmetric cold air jets exhausting at atmospheric pressure was studied. The mean flow and the statistical time averaged turbulence properties were measured. Spectra showed a very broad frequency content which shifted towards the lower frequencies as the flow progressed downstream. Axial wave number measurements indicate that the axial wave number-frequency relationship was the same for a wide range of Mach (0.3 to 2.5) and Reynolds (3,700 to over 200,000) numbers. Measurements of the azimuthal mode numbers show that several modes from n = -3 to +3 exist simultaneously in various quantities that the different frequencies studied. Acoustic measurements were made in the near field of the Mach number 0.6 jet. Sound pressure level contours showed that noise appeared to be radiated from a location near the end of the potential core. Directivity plots revealed that the spectra of this noise shifted towards higher frequencies as the angle from the jet axis increased. It was also found that mid-band excitation frequencies produced an increase in full spectrum noise.