消声器中频声学性能的计算测量方法

传统的消声器声学性能计算和实验测量都是在消声器进出口管道作为平面波声场的条件下进行,当进出口管道内出现有高阶模态激发的三维声场时,这些计算方法和实验测量方法就不再适用。由此,采用消声器进出口管道内加径向隔板的方法来计算消声器的声学性能,当原来管道声场中出现高阶模态时,仍然可以用平面波方法计算消声器的传递损失。应用该方法对进气滤清消声器进行传递损失数值计算,在原来进出口管道的平面波声场范围内,计算结果与传统方法计算结果均接近实验的测量结果,验证了该方法预测消声器声学性能的可行性。进而在所设计的消声器中频声学性能实验测试台架上,用声波分解法对阻性消声器进行传递损失测试,实验测量结果和有限元仿真结果也吻合良好。

Computational and Measurement Methods of Middle-frequency Acoustic Performance of Mufflers

The traditional calculation and measurement of muffler transmission loss are based on the assumption of plane wave propagation in the inlet and outlet ducts previously, which may not be used to predict the acoustical performance of muffler in the absence of the three-dimensional sound field excited by the higher-order modes in inlet and outlet ducts. A method is proposed to calculate the acoustical performance of muffler by adding radial plates inside the inlet and outlet ducts, and therefore the plane wave decomposition method still can be used to predict the transmission loss of muffler up to the second higher order modal frequency. This method is then applied to calculate the transmission loss of intake filter muffler, and the calculated results agree well with the experimental results and conventional finite element prediction, which confirms the applicability of the method. The test-bench for middle frequency acoustical performance of muffler is designed, and the plane wave decomposition method is employed to measure the transmission loss of a dissipative muffler. The measurement result and finite element numerical result are in good agreement in general.