等效流速修正的迭代加权离网格声源定位方法
Iterative weighted off-grid acoustic source identification method with equivalent flow velocity correction
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摘要: 在风洞内的声源定位实验中, 气流干扰使阵列难以近距离测量, 由于瑞利准则的限制, 传统波束形成方法对远场分布较近的多个低频声源难以实现高分辨率定位。为解决这一问题, 提出了一种基于等效流速修正的迭代加权离网格定位方法。首先, 建立离网格模型, 将声源强度与位置偏移补偿共同作为待求解变量; 然后, 通过等效流速法修正获得流场环境下的块传递函数; 最后, 基于迭代加权方法作为稀疏约束, 准确估计块稀疏解向量中的源强和离网偏差, 实现离网声源准确识别。在中国空气动力研究与发展中心的8 m × 6 m声学风洞内, 通过飞机标模搭载扬声器声源识别实验进行了方法验证。结果表明, 在40 m/s流速范围内, 传统方法的声源位置误差在0.27 m以上, 幅值误差在5 dB以上, 而本方法分别将位置与幅值误差降至0.17 m和3.9 dB。Abstract: In the wind tunnel sound source localization test, airflow interference makes it difficult for the array to measure at close range. Due to the limitation of the Rayleigh criterion, the traditional beamforming method is difficult to achieve high-resolution localization for multiple low-frequency sound sources with close distribution in the far field. To solve this problem, an iterative weighted off-grid localization method based on equivalent flow velocity correction is proposed. First, an off-grid model is established, with the sound source intensity and position offset compensation as the variables to be solved. Then, the block transfer function in the flow field environment is corrected by the equivalent flow velocity method. Finally, based on the iterative weighted method as a sparse constraint, the source intensity and off-grid deviation in the block sparse solution vector are accurately estimated, and the off-grid sound source is accurately identified. The method is verified in the 8 m × 6 m acoustic wind tunnel at the China Aerodynamics Research and Development Center, where an aircraft model is equipped with speakers for sound source identification experiments. The results show that in the range of 40 m/s flow velocity, the sound source position error of the traditional method is more than 0.27 m, and the amplitude error is more than 5 dB, while the position and amplitude errors of the proposed method are reduced to 0.17 m and 3.9 dB, respectively.
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