直通穿孔管消声器声学性能计算及分析

Acoustic attenuation performance calculation and analysis of straight-through perforated tube silencers

一维解析法和三维子结构边界元法被用于预测直通穿孔管消声器的消声性能.单腔直通穿孔管消声器传递损失的预测结果与实验测量结果比较表明:一维解析法只适合于消声器的低频声学分析;对于高频声学性能的精确预测需要使用三维处理方法.进而边界元法被应用于研究穿孔率和几何参数对直通穿孔管消声器消声性能的影响.增加穿孔率能够拓宽消声器的有效消声频率范围.中心管部分穿孔时,消声器的传递损失在平面波域内呈现出拱形衰减和轴向共振的叠加,合理选择穿孔段长度和位置以匹配共振和通过频率能够获得理想的宽带消声效果.使用双级膨胀腔能够大大改善直通穿孔管消声器的中频消声性能.

A one-dimensional analytical approach and a three-dimensional substructure boundary element method (BEM) are developed to predict the acoustic attenuation performance of straight-through perforated tube silencers. Comparisons of transmission loss predictions with experimental results for single chamber straight-through perforated tube silencers illustrated that the three-dimensional approach is needed for accurate prediction at higher frequencies, while the one-dimensional analytical approach provides a reasonable accuracy at lower frequencies only. The BEM was then used to investigate the effects of porosity and geometrical parameters on the acoustic attenuation performance of straight-through perforated tube silencers. Increasing the porosity may expand the effective acoustic attenuation to higher frequency. The transmission loss of silencer with partially-perforated tube exhibits a superposition of dome attenuation and axial resonance in the plane wave region. By choosing the length and location of perforated section to match the resonances with the troughs of the silencer, a desirable broadband acoustic attenuation may be obtained. The double expansion chamber may greatly improve the noise attenuation performance of straight through perforated tube silencers in the middle frequency range.