In-duct identification of a rotating sound source with high spatial resolution
In-duct identification of a rotating sound source with high spatial resolution
复制标题
DOI：
10.1016/j.jsv.2015.07.015
复制
发表时间：
2015-11
影响因子：
4.7
通讯作者：
Yong-ho Heo;J. Ih;H. Bodén
中科院分区：
文献类型：
--
作者：
Yong-ho Heo;J. Ih;H. Bodén
为了了解和降低管道内流体机械的流动噪声，有必要准确地识别声源特性。本文针对管道内旋转声源，研究了一种声源识别技术，它可以识别出主要声辐射体在声源平面上的强度和位置。基于模态求和法，建立了一个包含倏逝模和声源旋转效应的线性声学理论，该理论是反演声源重构的基础理论。在无流动的情况下，以两种不同的速度，在静态和旋转条件下，对由扬声器激励的管道系统进行了验证实验。由于源的旋转，所测量的压力谱揭示了多普勒效应，并且频移量对应于周向模式阶数和旋转速度的乘积。在固定坐标系下，估计了位移频率处的参与模态振幅，并收集了包含源旋转影响的模态振幅集，以研究旋转坐标系下的源行为。通过使用估计的模态振幅，近场压力被重新计算，并与测量的压力进行比较。在转速为300和600转/分时，获得的最大相对误差分别约为−25和−10 dB。从估计的模态振幅集合恢复声源参数的空间分布。结果表明，在旋转坐标系下，该方法能够以较高的空间分辨率识别出主声源的位置和大小。
To understand and reduce the flow noise generation from in-duct fluid machines, it is necessary to identify the acoustic source characteristics precisely. In this work, a source identification technique, which can identify the strengths and positions of the major sound radiators in the source plane, is studied for an in-duct rotating source. A linear acoustic theory including the effects of evanescent modes and source rotation is formulated based on the modal summation method, which is the underlying theory for the inverse source reconstruction. A validation experiment is conducted on a duct system excited by a loudspeaker in static and rotating conditions, with two different speeds, in the absence of flow. Due to the source rotation, the measured pressure spectra reveal the Doppler effect, and the amount of frequency shift corresponds to the multiplication of the circumferential mode order and the rotation speed. Amplitudes of participating modes are estimated at the shifted frequencies in the stationary reference frame, and the modal amplitude set including the effect of source rotation is collected to investigate the source behavior in the rotating reference frame. By using the estimated modal amplitudes, the near-field pressure is re-calculated and compared with the measured pressure. The obtained maximum relative error is about −25 and −10 dB for rotation speeds at 300 and 600 rev/min, respectively. The spatial distribution of acoustic source parameters is restored from the estimated modal amplitude set. The result clearly shows that the position and magnitude of the main sound source can be identified with high spatial resolution in the rotating reference frame.