Please use this identifier to cite or link to this item: `http://hdl.handle.net/11455/1962`
 標題: 脈動流流經二維擴散式消音器流場之數值探討A Numerical Study of Pulsating Flow Through Two-Dimensional Expansion Type Silencers 作者: 何松璟Her, Sung-Ching 關鍵字: Pulsating Flow;脈動流;Expansion Silencers;擴散式消音器 出版社: 機械工程學系 摘要: 本文主要目的以數值模式來分析機車引擎擴散式消音器內非穩態流場 特性，利用正弦變化之入口流速來模擬引擎間歇排氣，並針對四種擴散式 消音器結構進行探討。本文以SIMPLE之數值運算模式並利用 k-ε 雙方程 紊流模式來求解，假設流場為二維不可壓縮流流場，當流場達到一週期性 定態狀態後，由流場流線、速度分佈、壓力分佈、紊流動能及紊流能量消 散率五個流場特徵值來 分析流場特性。結果顯示在四種消音器中， 達到 週期性定態狀態後，週期性入口流速之流場特性已與均勻流明顯不同。而 消音器幾何形狀為影響流場結構和壓力變化之主要因素。The major goal of the present study is to numerically analyze the unsteadycharacteristics of flow fields inside expansion type silencers of motor engin-es. A sinusoidal inlet velocity is assumed intending to simulate the intermit-tent exhaust gas flow from the engine exhaust poot . The unsteady flow charac-teristics of four cases of expansion type silencers are studies . A Numericalscheme cheme based on SIMPLE algorithm and κ-εturbulence model are developedin this study . The flow is assumed to be two dimensional and incompressible .. The streamlines , velocities , pressures , and turbulence qu- antities ( tur-bulent kinetic energy and viscous dissippation ) , after the periodic steadystate being reached , are employed to analysze the flow field characteristics. The results show that , for all cases studied , the periodic steady flow fi-elds are greatly different from those with uniform inlet vlocity . It is also found that the geometrical arrangements are the main factors that affecting the flow structure and pressure variations . URI: http://hdl.handle.net/11455/1962 Appears in Collections: 機械工程學系所