排气系统振动噪声特性分析及改进

Analysis and Optimize Vibration and Acoustic Attribute for Exhaust System

某微型客车在800-1 900 rpm有明显的"嘟嘟"声及排气噪声偏大。本文采用仿真和试验相结合的方式,分析排气系统的振动、背压、消声器传递损失、尾管噪声、插入损失和功率损失特性。分析结果表明排气尾管发生共振,放大发动机高次谐波分量,是引起本排气噪声问题的主要原因。通过多方案分析比较,确定一合理优化方案,其排气噪声降低1-5dB(A),主驾驶员右耳噪声降低0.5-2.5 dB(A),满足功率损失比、插入损失和背压差标准要求,"嘟嘟"声明显减弱,声品质提高。

There are obviously toot noise between 800 rpm and 1 900 rpm, also, the exhaust noise is too high to accept. By combining simulation and empirical approach, this paper analyzes the behavior of vibration, backpressure, muffler transmission loss, tailpipe noise, insertion loss and power loss for one exhaust system. Results show that exhaust tailpipe has resonances which will amplify the high engine order tone. This is the main reason that causes toot and increases noise in the exhaust. One reasonable optimized case was proposed by comparing several cases, Whose exhaust noise reduced 1 to 5 dB（A）, and the noise of driver right ear reduced 0.5 to 2.6 dB（A）, and that met the criteria of power loss ratio, insertion loss and difference of back pressure, also, the toot attinuated significantly , the sound quality increased.