Please use this identifier to cite or link to this item: `http://hdl.handle.net/11455/2651`
 標題: 各種對衝流場之數值模擬與分析Numerical Simulation and Analysis of a Various Impinging Streams Flow Field 作者: 林正民Lin, Cheng-Min 關鍵字: opposing streams;對衝流場;combustion chamber;crossflow;mixing quality;燃燒室;橫向流;混合效果 出版社: 機械工程學系 摘要: 摘要 本文使用套裝軟體PHOENICS對二維層流或紊流對衝流場的混合效果及流體行為做綜合性的探討與分析。在層流中，直接建立Navier-Stokes方程式，並以控制體積積分法建立有限差分方程式，按SIMPLEST計算程序求解；而在模擬二維、不可壓縮之矩形對衝紊流流場，則採用修正後之Lam— 雙方程式紊流模式，並以控制體積積分法建立有限差分方程式，按SIMPLEST計算程序求解，分別就上下噴口速度比(VR)、噴口中心間距(S)、兩平板距離(H)及橫向流的有無( )等參數變化，分析它們對流場中速度、壓力、溫度及結構的影響。 經所得結果顯示，在無橫向流的對衝流場之下，無論是單噴對衝或是雙噴對衝，紊流所得的混合效果均較層流良好。且當上下噴口速度比愈大時，其所獲得溫度分佈愈均勻，混合狀況愈佳。隨著高度增加，其混合效果逐漸變差。當有橫向流時，其速度愈大，所挾帶動量也愈大，對於對衝流場則有較差的混合效果。 綜合言之，分析對衝流場的混合效果及流場結構，有助於了解空氣和燃油的混合，且更能充分掌握影響燃燒的因子，以提供業界在設計各種燃燒室上的參考。 關鍵字：對衝流揚、燃燒室、橫向流、混合效果Abstract In this study, a computational fluid (CFD) code, PHOENICS is used to calculate the flow field of 2-D double impinging streams to make the exploration of the comprehensive about mixing effects and flow behavior in two-dimensional opposed streams. In the laminar flow, directly construct the Navier-Stokes equation, and the control-volume integration formula for finite difference and SIMPLEST algorithm to solute. In the turbulence flow, the Lam correctional k-e two-equation turbulence model and the control-volume integration formula for finite difference and SIMPLEST algorithm are employed to simulate the two-dimensional, incompressible flow field. The velocity ratios (VR) of top jets to bottom jets, the nozzle to nozzle centerline spacing (S), the plate to plate distance (H) and the effect of the crossflow velocity ( ) on the flow field structure will be studied. From the numerical results, either single group or dual jets without crossflow, turbulent flow is better than laminar flow. When jets velocity ratio became larger, it got more uniform temperature distribution and mixing. But when the height is increasing, mixing quality got worst. Finally, analyzing mixing effects in the opposing streams and field structures, it would be helpful to understand the mixing of air-fuel ratio. The numerical results could prove industry to design all kinds of combustion chambers. Key Words: opposing streams, combustion chamber, crossflow, mixing quality URI: http://hdl.handle.net/11455/2651 Appears in Collections: 機械工程學系所