排氣系統的消音器模擬與分析

The Analysis and Simulation of Mufflers in Exhaust System

張峻瑋

指導教授 ： 許華倚

國立臺北科技大學/機電學院/機電整合研究所/碩士(2013年)

摘要

本研究主要是探討引擎排放出的氣體流經排氣系統中消音器所引發噪音、脈衝流噪音及傳輸損失模擬，並探討消音器內的多孔介質之不同孔隙率與消音器噪音的相互影響。
利用Fluent來模擬排氣系統內消音器之流場，求解三維穩態複雜模型、暫態簡易模型，使用不可壓縮流的Navier-Stokes方程式，搭配使用RANS描述流場狀態，紊流模型使用Standard k-ε模型，求解方法採用SIMPLE法則，利用聲音模型：FW-H模型和BNS模型顯示出流場及流場外的聲壓分布。
首先使用Pro-E來繪製消音器內部流場模型，再建構網格並設定邊界條件及求解方法，最後求得數值結果並與他人研究結果做比較，將結果最後用後處理匯出圖片及相關分析資料。

關鍵字

消音器 ； Fluent ； 多孔介質 ； 計算流體力學 ； 排氣噪音

並列摘要

The main objective of this work is to investigate the emissions of gas flowing through the engine exhausting system, the noise and the impulse noise caused by the muffler, and the flow simulation from the transmission losses. It is also important to explore the muffler with porous media using different porosities and the interaction between muffler noises.
The CFD tool has been used here to simulate the exhausting system and the flow field of the muffler. This is a three-dimensional incompressible steady-state flow which is solved by the Navier-Stokes equations. This turbulent flow is described as the RANS state of turbulence model. The Standard k-ε model is applied to solve this turbulent flow. The aerodynamically caused noise model used here are: FW-H model and the BNS model which separately show the flow field and the sound pressure distribution of the flow in unsteady state and steady state.
First, the computer-aided design drawing software has been used to draw the internal flow of the muffler, constructing the grid, setting equivalent boundary conditions and appropriate numerical methods, and finally the numerical results will be obtained to compare the results with other studies. The result will be finally exported as post-processing image to do the related research.

並列關鍵字

muffler ； Fluent ； porous media ； CFD ； exhaust noise

參考文獻

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