限制空間下的多層吸音板及反射式消音器的最佳化設計

Design Optimization on Multi-Layer Sound Absorbers and Reactive Mufflers Under Space Constraints

邱銘杰(Min-Chie Chiu)

指導教授 ： 張英俊 ； 葉隆吉

大同大學/工程學院/機械工程學系所/博士(2004年)

摘要

兩種消除噪音的基本元件-吸音板與反射式消音器，經常被應用於實務的噪音控制系統中，依據西元1970年所頒布的勞工職業安全與衛生法令的調查，噪音對工作者的身生理與心理，確實有極大的影響，因此，在密閉系統下的迴音控制，將顯得益形重要 ; 此外，在設備的操作與維修的便利性考量下，相對地，其附屬的消音元件-吸音板與反射式消音器，經常被要求侷限於特定的限制空間內，因而，”如何在限制空間的條件下，將噪音極小化”的有趣課題，便隨之衍生而出。
在吸音板與反射式消音器的學術研究上，雖然有很多好的發展，然而，在面對常見的 ”實務上噪音控制元件的空間限制問題”上，如何在空間限制下進行音響性能最佳化的研究與討論，卻鮮少(或未曾)被探討，因此，在空間限制下，以外型調整進行吸音板及消音器二者的吸音率與聲音穿透損失性能最佳化的研究，於焉在聲學領域展開。
本研究之各種吸音板與反射式消音器的數學推導，均以平面波理論為基礎並被完整推導，並以案例探討展現各種吸、減音元件的性能最佳化研究，包括(1)多層吸音板 ; (2)多腔消音器 ; 及(3)侷限機房多音源系統 等三類。
為了驗證已建立的上述各種吸、減音元件的數學模式的正確性，有關(1)正向吸音板的吸音量測 ; 及(2)消音器聲音傳遞損失量測 的實驗均分別被建立、量測，依據單層吸音板與單腔消音器的實驗量測結果，並比較上述的理論值顯示，二者頗為吻合。
在尋求數值最佳解上，本研究採用(1)傳統梯度法 (包括圈內罰則法、圈外罰則法、可行進方向法) ; 與(2)遺傳演算法，對上述各種吸、減音元件及系統進行最佳數值之求解。
本研究中，以案例探討展現各種吸、減音元件的性能最佳化研究，上述模擬結果可提供噪音學家做多重的選擇，最後，本研究結果顯示，以遺傳演算技術進行最佳數值求解，確實比傳統梯度法容易、有效。

關鍵字

數學梯度法 ； 遺傳演算法 ； 消音器 ； 吸音板 ； 最佳化 ； 空間限制

並列摘要

Sound absorbers and Reactive mufflers, the elementary devices in noise elimination, are habitually applied in practical noise control system. As investigated by the Occupational Safety and Health Act (OSHA) in 1970, noise is highly responsible for the psychological and physiological ills to workers. Therefore, the noise control for an enclosed system with high echo effect becomes essential. Besides, the space volume of adopted anti-noise devices, sound absorbers and reactive mufflers are occasionally constrained for the necessity of operation and maintenance on equipment, the interest in minimizing the noise under space constraints is then arising.
Many researches of sound absorbers and mufflers were well developed; however, the discussion of performance optimization on these elements under the space constraints was rarely accomplished even though the limited space of the noise-eliminating device is demanded intermittently. And so, the interest to optimize the noise reduction abilities such as the sound absorption of sound absorbers and the sound transmission loss (STL) of mufflers by adjusting the shape parameters is arising in the field of acoustics.
On the basis of plane wave theory, all the mathematical models of sound absorbers and reactive mufflers were completely derived. Case studies regarding the multi-layer sound absorbers, various types of multi-chamber mufflers and the multi-noises inside a confined machine room were exemplified and fully discussed.
To verify the correctness of the mathematical models on the anti-noise fundamental elements, several experimental works, including (1) the normal sound absorption on sound absorbers and (2) the sound transmission loss on mufflers, were built up and tested individually. Results of the sound absorption on single-layer sound absorber and the STL on single-chamber muffler give a good confirmation between theory and experiments.
In solving the optimal solutions, (1) the traditional gradient methods – interior penalty function method, exterior penalty function method, method of feasible direction; and (2) the genetic algorithm (GA) were applied.
In the studies, several kinds of mufflers and sound absorbers were exemplified and optimized. The simulated results provide the multiple options for the acousticians. Consequently, the results reveal that the numerical assessment in GA techniques becomes easier and efficient than that in gradient method.

並列關鍵字

genetic algorithm ； mathematical gradient method ； muffler ； optimization ； sound absorber ； space constraints

參考文獻

[28] Y. C. Chang, L. J. Yeh, M. C. Chiu, G. J. Lai, “Computer aided design on single expansion muffler with extended tube under space constraints,” Tamkang Journal of Science and Engineering. 7 (3) (2004), 171-181.

[29] Y. C. Chang, L. J. Yeh, M. C. Chiu, “GA optimization on single-chamber muffler hybridized with extended tube under space constraints,” Archives of Acoustics. (Accepted, 2004)

[30] L. J. Yeh, Y. C. Chang, M. C. Chiu, G. J. Lai, “Computer-aided optimal design of a single-chamber muffler with side inlet/outlet under space constraints,” Journal of Marine Science and Technology, 11 (4) (2003), 189-196.

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