基于SODIX方法的叶片前缘噪声指向性及降噪实验研究

Experimental study on the directivity and noise reduction of the blade leading-edge noise using Inverse Method SODIX based on microphone array

  • 摘要: 以NACA 65(12)–10独立基准叶片为对象,使用线性传声器阵列和SODIX(SOurce DIrectivity modeling in the cross-spectral matriX)方法对基准叶片前缘噪声指向性分布特征及波浪前缘对叶片前缘噪声的影响进行了实验研究。开发了SODIX数据处理程序并进行了数值仿真验证,结果表明:不同指向角下计算结果的最大误差不超过0.26 dB。在半消声室内,利用由31个传声器组成的非均匀分布优化阵列,对NACA 65(12)–10独立基准叶片和仿生学叶片的前缘噪声开展了参数化声学实验。结果表明:在40°~142°指向角测量范围内,基准叶片前缘噪声指向性符合典型偶极子声源特征,峰值在130°指向角附近;随着频率升高,基准叶片前缘噪声指向性产生了显著的“波瓣”现象,频率越高,“波瓣”越多。进一步研究表明:不同波长和幅值的前缘构型都可以有效降低指向角测量范围内的前缘噪声;与波浪前缘的波长相比,波浪前缘的幅值对前缘噪声的影响更为显著,特别是在90°~120°指向角范围内,A30W20叶型的降噪量可达7.71 dB。

     

    Abstract: Taking the NACA65(12)–10 blade as the object, a linear microphone array based on the SODIX (SOurce DIrectivity modeling in the cross-spectral matriX) method is used to study the leading-edge (LE) noise directivity of the baseline and the effect of the wavy LE on the LE noise directivity. First, a SODIX data processing program was developed, and the program was validated by numerical simulation. The validation results show that the data processing program has a good accuracy with an error less than 0.26 dB. Then, a linear array with 31 microphones is designed to identify the LE noise directivity of the baseline and the wavy LE blade experimentally in a semi-anechoic chamber. Within the measured degree range of 40°–142°, the directivity of LE noise shows a characteristic of typical dipole sound sources with a peak occurs at 130°. Besides, the higher the frequency is, the more obvious of the ‘lobe’ distribution of the LE noise directivity is. Further analysis shows that the wavy LE with various amplitudes and wavelengths especially with larger amplitudes can reduce LE noise in measured angle ranges especially among 90°–120°. And the maximum value is 7.71 dB for A30W20.

     

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