喷流近场噪声源的高阶波包模型与反演方法
A high-order wavepacket model and inversion method for jet near-field noise sources
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摘要: 传统的阵列测量反演方法只适用于远场噪声预测, 无法获取近场声源信息, 为此提出了一种适用于喷流近场声辐射的等效声源模型, 及其基于阵列测量的声源反演方法, 反演的结果可用于预测喷流近场噪声。首先, 声源模型基于双曲正切型波包, 将周向阶次从0阶扩展到高阶螺旋模态。其次, 通过设计的环形声阵列测量确定了主导阶次, 并采用主成分分析方法获得了螺旋模态功率。然后, 通过PIV测量, 确定波包模型的径向等效半径和轴向截断距离。最后, 基于归一化模态功率的轴向分布, 通过最小化模型计算和试验测量之间的误差, 反演声源模型参数。高阶螺旋模态波包模型对喷流近场噪声的计算结果与试验结果的平均误差小于1 dB, 验证了所提高阶等效声源模型和反演方法的准确性。Abstract: Conventional source inversion and sound field reproduction method based on microphone array are only applicable to jet far-field noise. An invertible equivalent source and its inversion method for jet near-field noise are proposed in this study. The inversion results can be utilized to reproduce the jet near-field noise. Firstly, the acoustic source model is constructed based on a tanh-type wavepacket, with the azimuthal order extended from the traditional axisymmetric mode to higher-order helical modes. Next, the dominant modes are identified through measurements using a designed circular array, and accurate helical mode power is calculated using principal component analysis. Then, a method based on the PIV measurements is proposed to determine the radial equivalent radius and axial truncation distance of the wavepacket model. Finally, an inversion method is proposed by minimizing the error between the calculated and measured axial distribution of normalized modal power. Experimental results demonstrate that the proposed wavepacket model accurately computes jet near-field noise, showing close agreement with measured data, with an average error of less than 1 dB. The accuracy of the proposed equivalent source model and the inversion method is thereby validated.
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