臺灣博碩士論文加值系統

本研究是利用數值模擬的方法，分為兩階段來探討輪圈幾何形狀對大客車空氣動力行為之影響，第一階段：對獨立輪圈系統透過輪圈幾何形狀的差異，輪圈表面位置的改變以及輪圈在有無旋轉等參數，探討出上述之各種參數對輪圈空氣動力行為之影響。第二階段：將車輪裝置於大客車上，在不同幾何形狀之車輪以及車輪有無旋轉等參數下，經由上述之各種參數來探討車輪對大客車空氣動力行為之影響。經由數值計算模擬分析結果顯示：早期的輪圈空氣動力行為分析都是以簡單的平面車輪並在車輪無旋轉之狀態下及未裝置於車輛上來模擬分析車輪空氣動力行為，但是在本文中發現到不同的車輪形狀之差異、車輪有無旋轉之狀態以及車輪是否有裝置於車輛上所得到的阻力係數、升力係數都有明顯的差異，因此說明了：以數值模擬的方法來做相關的數值分析，若要得到更確實的分析結果，其所建立的計算模型愈接近實體模型及所設定之參數愈符合實際邊界條件是必須詳加考慮之。在探討車輪有無旋轉對於獨立輪圈空氣動力行為之影響，發現輪圈在未旋轉時的阻力、升力係數會大於輪圈旋轉時的阻力、升力係數，但是隨著輪圈的旋轉速度的增加，其阻力、升力係數改善的幅度越來越小。甚至有惡化之虞。另外在探討車輪裝置於大客車上以發現到車輪在旋轉時的阻力、升力係數會大於車輪未旋轉時的阻力、升力係數。

關鍵字：輪圈、車輪、數值模擬、空氣動力學行為、阻力係數、升力係數

This research uses the process of numerical simulation to study the effect of rim geometry of a bus. The numerical work in this thesis is divided into two stages. The first stage was to determine the aerodynamic behavior of a suitable single rim shape by considering different rim shape geometric parameters such as the rim surface position, the shift pattern, and the non-spinning condition. The second stage was to apply the rim shape to a bus. Based on current numerical results, it was found that early models of aerodynamic effect on rim shape geometry were somewhat less practical because they were determined using simple criteria such as flat surface and un-motional rim spin condition. However, in this thesis, we discovered that the bus would experience different drag and lift forces under the influence of rim shape geometry and rotational speed. By using more practical models, rim rotation conditions, and different shapes, we have obtained a more complete analysis of actual aerodynamic effect of a bus. The simulations have shown that the drag and lift coefficients of individual rim decrease as rim rotational speed increases. However, if identical rims are placed on a bus, the results are exactly opposite.


Keywords: Rims, Wheels, Numeric Simulation, Aerodynamic Behavior, Drag Coefficient, Lift Coefficient

目錄
摘要………………………………………………………………………….I
Abstract……………………………………………………………………..II
誌謝………………………………………………………………………..III
目錄………………………………………………………………………..IV
表目錄…………………………………………………………………...VIII
圖目錄……………………………………………………………...……...XI
第1章 前言………………………...……………………………………...1
1.1 研究動機………………………………………………………….....1
1.2文獻回顧………………………………………………………..........2
1.3 本文內容………………………………………………………….....6
第2章 數學模式…………………...……………………………………...8
2.1 流場之基本假設………………………………………………….....8
2.2 統御方程式……………………………………………………….....9
2.3 邊界條件…………………………………………………………...12
2.3.1 獨立不同形狀輪圈之計算模型系統…………………………13
2.3.1.1 輪圈旋轉速度不同之探討…………………………...........15
2.3.1.2 輪圈與地面接觸情形之探討……………………………...15


2.3.2 裝置不同幾何形狀及不同車輪數目之大客車計算
模型系統………………………………………………………16
2.3.3 底盤輪圈系統之阻力、升力係數公式說明…………………18
2.4 數值方法…………………………………………………………...18
2.4.1 離散方式(Discretisation Schemes)……………………………18
2.4.2 壓力與速度(Pressure-velocity coupling)之耦合算法………...20
2.5 格點系統………………………………………………………….. 22
2.6 收斂標準…………………………………………………………...25
第3章 結果與討論...…………………………………………………….26
3.1輪圈之幾何形狀、表面位置及旋轉速度對輪圈空氣動
力行為之影響………………………………………………………26
3.1.1輪圈旋轉速度對不同幾何形狀輪圈空氣動力行為之影響.…29
3.1.2 不同幾何形狀之輪圈其輪圈表面位置距離輪圈中
心50mm之探討………………………………………………34
3.1.3 不同幾何形狀之輪圈其輪圈表面位置距離輪圈中
心140mm之探討……………………………………………..36
3.1.4 輪圈幾何形狀相同其表面位置不相同之探討………………37
3.2 車輪幾何形狀與車輪數目對大客車空氣動力行為之影響...........39
3.2.1 車輪數目之影響………………………………………………39

3.2.1.1 車輪數目不同之大客車整體阻力、升力係數探討……...39
3.2.1.2 車輪數目不同之大客車前車輪阻力、升力係數探討…...41
3.2.1.3 車輪數目不同之大客車外側後車輪阻力、升力係數
探討..………………………………………………………47
3.2.1.4 平面輪六輪大客車內側後車輪之空氣動力行為之探
討…………………………………………………………..54
3.2.1.5 車輪數目不同之大客車車體本身阻力、升力係數探
討…………………………………………………………..57
3.2.2車輪幾何形狀不同之影響…………………………………….60
3.2.2.1 車輪幾何形狀不同之大客車整體阻力、升力係數探討...61
3.2.2.2 車輪幾何形狀不同之大客車前車輪阻力、升力係數
探討………………………………………………………..62
3.2.2.3 車輪幾何形狀不同之大客車外側後車輪阻力、升力
係數探討…………………………………………………..70
3.2.2.4 車輪幾何形狀不同之大客車內側後車輪阻力、升力
係數探討…………………………………………………..75
3.2.2.5 車輪幾何形狀不同之大客車車體本身阻力、升力
係數探討…………………………………………………..79
第4章 結論………………………………………………………………82
參考文獻…………………………………………………………………..84
作者簡介…………………………………………………………………..87

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