多共振消声器串联系统声学特性分析及应用

针对内燃机进气系统需良好的低频消声效果而可用空间有限的问题，研究多个消声器串联后的声学特性。基于共振消声器集中参数模型，推导消声器串联后系统主消声频率公式并验证。结果表明，双共振消声器串联系统有两主消声频率，即小于、大于下端消声器的偏频；增加体积比时较小的接近偏频，较大的远离偏频；长度比等于1、面积比小于等于1时串联系统所需体积小。串联系统消声器结构参数均相同时主消声频率个数与消声器个数相同。基于此，对某商用车进气系统进行降噪设计，使200 Hz以内的传声损失整体提高约5 dB。

Acoustic performance analysis and application ofthe series-wound system of multi-resonant silencer

The good performance of low frequency noise reduction contradicts the limited space of the intake system of the internal combustion engine. Aiming at this problem the acoustic performance of the series-wound system of multi-resonant silencer was studied. Based on the lumped parameter model of the resonant silencer, the formula of the main resonant frequencies of the series-wound system of multi-resonant silencer were deduced and verified.Study shows that the series-wound system of double-resonant silencer has two main resonant frequencies, as one is smaller than the bias frequency of the bottom resonant silencer, and the other one is bigger. Along with the volume ratio increasing, the smallerresonant frequency gets close to the bias frequency,whilethe bigger one gets away.The total volume needed in series-wound system is smaller than in parallel systemwhile length ratio = 1 and area ratio 1.When the structure parameters of theresonant silencers of the series-wound system are the same, the number of the main resonant frequencies equals to the number of the silencers.Based on theseconclusions,the intake system of a commercial vehicle was redesigned with the transmission loss below 200Hz increased by about 5dB over all.