Theory and application of reverberated direct and indirect noise
Theory and application of reverberated direct and indirect noise
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直接和间接混响噪声的理论与应用
DOI：
10.1017/jfm.2017.183
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发表时间：
2017
影响因子：
3.7
通讯作者：
S. Hochgreb
中科院分区：
文献类型：
--
作者：
E. O. Rolland;F. De Domenico;S. Hochgreb
流动中温度扰动的产生伴随着声波（直接噪声）和熵扰动的产生。如果这种熵扰动被加速或减速（如通过喷嘴或流量限制的情况），则会产生额外的声波（间接噪声）。一些研究已经通过使用熵波发生器在受控条件下证明了这种机制，其中产生熵波并通过喷嘴对流，导致直接和间接噪声。本文对反射环境中熵波的产生和加速所产生的直接和间接噪声进行了分析。混响（重复的声反射）对低频扰动（熵波发生器的特性）的影响是解析确定的。这些结果，然后实施在一组极限情况下，显示这种系统的极限行为。分析模型的情况下，剑桥熵波发生器实验中，熵波产生的电加热器和加速通过亚音速孔板。由于实验结果中直接噪声和间接噪声在时间上有明显的分离，因此首次可以从实验数据中提取直接噪声和间接噪声传递函数，并直接与现有的理论模型进行比较。在孔板处产生的向后传播的间接噪声被证明是显着高于现有的等熵喷嘴的理论模型预测。
The generation of a temperature disturbance in a flow is accompanied by the production of acoustic waves (direct noise) and of an entropy perturbation. If this entropy perturbation is accelerated or decelerated (as is the case through a nozzle or flow restriction), additional acoustic waves are generated (indirect noise). Several studies have demonstrated this mechanism in controlled conditions by using entropy wave generators, in which entropy waves are generated and convected through a nozzle, leading to direct and indirect noise. An analytical analysis of the direct and indirect noise produced by the generation and acceleration of entropy waves in a reflective environment is presented. The effect of reverberation (repeated acoustic reflections) on low-frequency perturbations (characteristic of entropy wave generators) is determined analytically. These results are then implemented in a set of limit cases, showing the limit behaviours of such systems. The analytical model is applied to the case of the Cambridge entropy wave generator experiment, in which entropy waves are generated by an electric heater and accelerated through a subsonic orifice plate. Due to the clear time separation of direct and indirect noise in the experimental results, direct and indirect noise transfer functions can be extracted from the experimental data for the first time and compared directly with existing theoretical models. The backward-propagating indirect noise generated at an orifice plate is shown to be significantly higher than predicted by existing theoretical models for isentropic nozzles.
检测管道中合成热点产生的直接和间接噪声
DOI：
10.17863/cam.8524
发表时间：
2017
期刊：
--
影响因子：
--
作者：
De Domenico F
通讯作者：
De Domenico F