消声元件安装位置对消声效果的影响

分别以消声量和管口阶次噪声作为评价指标,研究消声元件安装位置对消声效果的影响规律,设计在直管不同位置安放四分之一波长管的消声量测量试验对消声量评价。结果表明:设计频率声模态下,在反节点处安装波长管消声量最大,与理论分析完全吻合;进一步对消声量进行仿真计算,结果与试验完全相符。对于管口噪声指标评价,设计频率为267 Hz的谐振腔解决某发动机4000 r/min时进气管口存在4阶噪声引起的噪声峰值问题,对比谐振腔安装在进气管路该频率附近的声模态反节点和节点位置的管口4阶噪声,可知谐振腔布置在反节点位置比节点位置噪音降低了24 dB。两个案例充分证明声学系统模态反节点位置是消声元件的最佳布置位置。

The influence of the reduction effect of the location of silencing element

In order to research the influence of the reduction effect of silencing element location,the noise reduction and tailpipe order noise are used as index.An experiment is designed to measure the noise reduction of a quarter wavelength tube which is assembled in different locations.The results show that noise reduction is maximum when wavelength tube is located at the anti-node of the acoustic mode of design frequency,which could be proved by theoretical analysis.Further simulation is completely conformed with experiment result.For the evaluation of the tailpipe noise,in order to resolve the peak noise problem caused by 4 th order noise at 4000 r/min,a resonator of 267 Hz is designed and tested.Comparing the tailpipe 4 th order noise when the resonator is located at the anti-node of the acoustic mode and that at the node,it is shown that noise for anti-node reduced 24 dB(A)more than that of node.It proves that anti-node location is the best installation position of silencing element.