排气消声器传递损失的实验测量与分析

介绍消声器传递损失的测量方法，包括声波分解法、两负载法、两声源法和脉冲法。在消声器声学性能试验台上采用两负载法测量无流和有流时简单膨胀腔和直通穿孔管消声器的传递损失。测量结果表明：穿孔率对穿孔管消声器低频消声性能影响较小，对中高频消声性能影响较大，增加穿孔率能够拓宽穿孔管消声器的有效消声频率范围；气流对直通穿孔管消声器的声学性能有一定影响，穿孔率越低影响越大，随着流速的增加，低频段传递损失变化不大，高频段的传递损失显著增加。

Experimental Measurement and Analysis of Transmission Loss of Exhaust Silencers

The methods for measuring transmission loss of silencer, including wave decomposition method, double-load method, double-source method, and impulse method, are introduced. The doubleload method is used to measure the transmission losses of simple dilatation chamber and straight-through perforated tube silencers in the cases of flow and flow-free on the test-bed. The measurement results show that the porosity of perforated tube has minimal influence on the acoustic attenuation performance on silencers in lower frequency range, but the effect is large in the medium and higher frequency range. As the porosity increases, the range of the effective acoustic attenuation is extended. The airflow has some influence on the acoustic performances of the straight-through perforated tube silencers. The lower the po- rosity is, the larger the influence is. With increasing of the airflow rate, the transmission loss changes insignificantly at lower frequencies, and increases obviously at higher frequencies.