用声模态技术识别内燃机噪声源

为了准确识别内燃机噪声源，提出了一种声模态分析技术.通过对双传声器声强信号进行傅里叶变换，得到两个声压互谱的虚部，进而计算出各测点声强的频率分布，将测量面上各测点某一频率成分的声强值挑选出来，得到测量面上各频率成分的声模态.用声模态技术对一台汽油发动机噪声源识别，确定了各测量面的主要噪声源的位置，并对噪声源产生机理进行了分析.结果表明，声模态技术能准确识别出测量面上各种频率成分的噪声源位置，为噪声控制的结构改进和声源屏蔽提供重要信息.

Noise source identification of internal combustion engine using sound mode technology

A sound mode technology was proposed for exactly identifying an internal combustion engine's noise source.After the Fourier transformation of the sound intensity signals from the two microphones was performed,the imaginary parts of two sound pressure's cross spectrums were obtained,and the sound intensity frequency distribution of every measuring point was calculated.By extracting the sound intensity of every point on the measuring surface at some frequency,the sound mode at every frequency component was achieved.After the noise source of a gasoline engine was identified using the sound mode technology,the distribution of the key noise source was determined at every measuring surface,and the causative reasons inducing the sound source were analyzed.The results indicate that the sound mode technology can exactly identify the noise source distribution of the measuring surface at every frequency component,and provide significant information for the structural optimization and noise source shielding.