Jet Noise Scaling in Dual Stream Nozzles
Jet Noise Scaling in Dual Stream Nozzles
复制标题
双流喷嘴中的射流噪声缩放
DOI：
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发表时间：
2010
期刊：
影响因子：
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通讯作者：
J. Bridges
中科院分区：
文献类型：
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作者：
A. Khavaran;J. Bridges
将双流同轴射流视为适当的单流同轴射流的叠加，研究了双流射流的功率谱规律。每个混合区的噪声产生是使用先前为单流射流开发的频谱功率定律作为射流温度和观察者角度的函数来模拟的。相似论证表明，双流喷嘴中的喷流噪声可视为代表主/次、次/环境、过渡区和完全混合区的四个单流急流的复合体。频率滤光器的设计突出了每一股喷流的光谱贡献。在面积比为2.0，旁路比从0.80到3.40的范围内进行了预测，并在很大的速度比和温度比范围内与测量结果进行了比较。这些模型表明，在所有速度比下，非加热射流中的低频噪声以完全混合区为主，而当速度比大于0.80时，高频噪声以次要噪声为主。过渡射流和完全混合射流同样控制加热射流中的低频噪声。当速度比小于0.50时，主/旁路的高频噪声成为与二次/环境射流相似的重要贡献因素。
Power spectral laws in dual stream jets are studied by considering such flows a superposition of appropriate single-stream coaxial jets. Noise generation in each mixing region is modeled using spectral power laws developed earlier for single stream jets as a function of jet temperature and observer angle. Similarity arguments indicate that jet noise in dual stream nozzles may be considered as a composite of four single stream jets representing primary/secondary, secondary/ambient, transition, and fully mixed zones. Frequency filter are designed to highlight spectral contribution from each jet. Predictions are provided at an area ratio of 2.0--bypass ratio from 0.80 to 3.40, and are compared with measurements within a wide range of velocity and temperature ratios. These models suggest that the low frequency noise in unheated jets is dominated by the fully mixed region at all velocity ratios, while the high frequency noise is dominated by the secondary when the velocity ratio is larger than 0.80. Transition and fully mixed jets equally dominate the low frequency noise in heated jets. At velocity ratios less than 0.50, the high frequency noise from primary/bypass becomes a significant contributing factor similar to that in the secondary/ambient jet.