排煙消音器之聲學性能與結構參數之研究

The Study of Structural Parameters for Exhaust Mufflers on Acoustic Performance

鄔詩賢(James Shih-Shyn Wu) ； 黃敏祥(Min-Hsiang Huang)

《中華民國振動與噪音工程學會論文集》 2014 (2014/06) Pp. 73-78

摘要

本研究應用自主開發之有限元素分析軟體，針對車用排煙消音器進行傳輸損失(TL)性能分析，並透過實驗比對，驗證有限元素分析方法的正確性。再藉由不同腔室設計、截面積形狀、橢圓度等參數化之研究分析，探討消音器最佳設計參數。配合外殼結構振動，進行聲振耦合模擬分析，以進一步瞭解振動對排氣音的影響。研究結果發現：(1)流體溫度和排氣管長度會改變TL波谷頻率位置；(2)多腔室會增加中、高頻率的TL，達到更好性能設計；(3)增加橢圓截面的高/寬比，會使TL的截止頻率往低頻移動；(4)不同外殼厚度所引發之振動模態對消音器中、高頻段的傳輸損失有較大影響因素，同時管壁俓向模態對消音器低頻段傳輸損失則有顯著的提升。本研究以參數化之分析建立消音器空腔設計與外殼振動與傳輸損失性能關係，提供消音器在性能設計階段有更正確之預估結果。

關鍵字

消音器 ； 傳輸損失 ； 聲振耦合 ； 有限元素 ； 轉移函數

並列摘要

In this project, significant information for optimum muffler design using the FE approach is studied. In verification of the function of the FE software system designed, some experiments for a single chamber muffler with circular sectioned and constant shell thickness are done here. Comparison with the acoustic performance among various mufflers, chamber baffles, different length and aspect ratios of section, etc. are investigated. The influence of vibration of external shell of the muffler performance is also studied according to the limits of the available space and frequency range interested on tail pipe noise elimination. Results obtained here show : (1) the air temperature and length of exhaust pipe may affect TL for lower frequency portions, (2) multi-chambers may increase TL in the mid- and high-frequency, produce better design, (3) the increment of aspect ratio of elliptical section affects the cut-off frequency seriously, (4) various vibration modes of external shell with different thickness may affect the TL response in the mid- and higher frequency ranges and the tensile mode may increase the TL in the lower frequency range obviously.

並列關鍵字

muffler ； transmission loss ； vibro-acoustic ； finite element ； experiment