臺灣博碩士論文加值系統

本研究在於藉由引擎進氣道幾何的設計，以產生強烈的進氣渦流。運用計算流體力學之商用軟體－FLUENT，採用 紊流模型計算穩態單缸四汽門機車引擎進氣道流場，模擬引擎在流量測試平台的真實情況，研究方法是直接使用引擎設計時的3D CAD檔案進行分析，最後並將計算出的流量係數(Flow coefficient, )及渦旋比(Swirl ratio, )與實驗值作一比較；結果發現原廠氣道雙閥開啟案例中，在進氣閥開度小的時候預測相當準確，誤差百分比為1.14%；而原廠氣道單閥開啟案例是由關閉右側進氣門的方式，使氣流導引至汽缸的切線方向產生渦流以計算渦旋比，其結果顯示在氣門開度大時運用高階離散法可獲得良好之準確度，其整體平均渦旋比為2.041，相對誤差百分比僅為0.443%；然後利用氣道形狀的幾何修改，設計一弧線角度改變氣流的運動方向，使以達到引擎進氣渦流設計的目的，其結果顯示相較於原廠氣道單閥開啟得到更強烈的進氣渦流，其整體平均渦旋比為3.784。

This paper focuses on the design of engine intake port geometry, in order to generate strong charge swirling flow. Using computational fluid dynamics commercial software-FLUENT, adopt turbulence model to calculate intake flow field of a single cylinder four-valve motorcycle engine in steady state. To simulate the real condition that engine intake flow test by flow bench. The method is to analyze 3D CAD file directly while engine design. Finally, compare the flow coefficient and the swirl ratio value with experiment data. The result of twin-valve opening of original intake port case displays an accurate prediction while low valve lift and the error is 1.14%. The other one original case by closing right-hand intake valve makes air flow to cylinder tangentially. It will generate swirl then calculate the swirl ratio. The result displays a good accuracy by using high order discrete scheme while wide valve lifts, and the average swirl ratio is 2.041. The error is only 0.443%. Then modify the intake port geometry, design a curve angle to change air flow direction. To achieve the target of engine intake swirling flow design. The result gets stronger swirling flow than second one. The average swirl ratio is 3.784.

摘　要 i
ABSTRACT ii
誌 謝 iv
目 錄 v
表目錄 vii
圖目錄 viii
第一章 緒論 1
1.1 研究背景與動機 1
1.2 文獻回顧 5
1.3 研究目的與方法 12
第二章 基本理論 14
2.1 統御方程式 14
2.2 紊流模型 15
第三章 數值方法 18
3.1 數值模擬 18
3.1.1 前處理器 18
3.1.2 數值求解器 20
3.1.3 後處理器 21
3.2 研究假設條件 22
3.3 幾何外型及邊界條件設定 23
3.4 格點獨立分析 29
3.5 離散方法比較 30
3.6 收斂條件與鬆弛因子 31
第四章 實驗設備與方法 33
4.1 實驗設備與裝置 33
4.1.1 流量測試台 33
4.1.2 渦流量測儀 35
4.1.3 實驗引擎 35
4.1.4 大氣壓力計 36
4.2 實驗方法 37
第五章 實驗及模擬之結果與討論 41
5.1 流量測試實驗量測結果 41
5.1.1 雙氣閥開啟實驗結果 41
5.1.2 單氣閥開啟實驗結果 42
5.2 CFD流場模擬結果分析 44
5.2.1 原廠氣道雙氣閥開啟模擬結果 44
5.2.2 原廠氣道單氣閥開啟模擬結果 50
5.2.3 切向螺旋氣道模擬結果 56
第六章 結論與未來展望 62
6.1 結論 62
6.2 未來展望 63
參考文獻 64
符號彙編 68
著作發表 70

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