近年來大雨造成許多飛安事故，世界各國越來越關心飛機在惡劣天氣下的狀況，尤其是水漂現象，因為水漂現象是最常發生在起飛和降落時的事故，即使不是在惡劣天氣下。雖然通常不會發生太嚴重的意外，但從航空公司的觀點，旅客有安全的飛行體驗才是最重要的事。在此篇論文中，將會使用CFD軟體ANSYS Fluent研究輪胎水漂現象的空氣動力學。在輪胎的研究中，Fackrell的A2輪胎是最常被使用來當作驗證的案例，由於輪胎是與地面接觸的，在接觸面的外型設定是很重要的以防止產生高歪斜度的網格。C_L和C_D的結果與實驗比較，誤差都小於1%。再來則是使用流體體積法(VOF)來處理二項流的問題。儘管使用不同的數值模擬方法模擬水漂現象，但我們的結果仍然顯示出目前使用的水漂現象模型與過去的結果有定性與定量上的相似，此外我們在本研究中以一個創新且直接的方法實現了模擬動態水漂現象。

In recent years, many aviation accidents that caused by weather have occurred, so the world is more and more concerned about the situation of airplane under bad weather. Especially the hydroplaning phenomenon, due to hydroplaning phenomenon is the most often happened accident when airplane taking off and landing, even if not under a bad weather. Although, it usually will not cause a serious accident but from the viewpoint of airline, the safety and the flight experience of passengers is obviously the most important thing. In this thesis, we will use ANSYS Fluent, the Computational Fluid Dynamics (CFD) software, to study the aerodynamics of hydroplaning phenomenon on an isolated wheel. Before that, first, have to study the aerodynamics of isolated wheel. In the study of the isolated wheel, Fackrell’s A2 wheel is the most common used benchmark and use in this thesis. At beginning, due to the wheel is contact with ground, the geometric setup of contact patch is important in this simulation in order to prevent high skewness. The results of C_L and C_D of A2 wheel model comparing with experiment results are all under 1% error. Secondly, the simulation of hydroplaning phenomenon utilizes the Volume of Fluid (VOF) method to simulate the two-phase flow problem. Although using different numerical simulation approach, our results still show that the current hydroplaning model is qualitatively similar to the results of earlier works. Furthermore, it can be claimed that an innovative and straight forward approach to simulate the dynamic hydroplaning phenomenon have been achieved.

Abstract	                                      III
Contents	                                      V
List of Figures	                                      VI
List of Tables                                        IX
List of Symbols	                                      X
Chapter 1	Introduction                          1
1.1	Hydroplaning Phenomenon                       2
1.2	Three Zone Concept of Hydroplaning            5
1.3	Aviation Safety                               6
Chapter 2	Literature Review                     8
2.1	The Aerodynamics of Wheel                     8
2.2	Fackrell Wheel                                9
2.3	Computational Fluid Dynamics of Wheel         11
2.4	CFD of Hydroplaning Phenomenon                13
Chapter 3	Numerical Modeling                    18
3.1	Geometry Model Construction                   18
3.2	Grid Generation                               20
3.3	Governing Equations and Turbulence Modeling   22
3.4	Numerical Setup                               29
3.5	Volume of Fluid (VOF) Method                  31
3.6	Hydroplaning Model Setup                      35
Chapter 4	Results and Discussions               40
4.1	Validation of A2 Wheel                        40
4.2	Results of Hydroplaning Phenomenon            43
Chapter 5	Conclusions                           59
References                                            60

List of Figures
Figure 1	Hydroplaning phenomenon [1]	1
Figure 2	Dynamic hydroplaning [2]	2
Figure 3	Viscous hydroplaning [2]	4
Figure 4	Reverted rubber hydroplaning [2]	5
Figure 5	Three zone concept of hydroplaning [5] [6]	6
Figure 6	The ASDE track of CI680 landing on Taoyuan International Airport on August 12, 2012 [7]	7
Figure 7	The landing route of PC2193 on Istanbul Sabiha Gökçen International Airport [8]	7
Figure 8	Wheel axis system defined by SAE standards [9]	8
Figure 9	Pressure distribution of B2 wheel rotation and stationary [10]	10
Figure 10	Symbols for formula [10]	11
Figure 11	The three types tire tread pattern, T1 (smooth), T2 and T3 [19]	15
Figure 12	The simplified tire model of Zhou [20]	16
Figure 13	Dimensions of A2 wheel (in mm) [14] [15]	18
Figure 14	The step of wheel and ground contact section	18
Figure 15	The wind tunnel size same as computational domain [13]	19
Figure 16	The overall computational domain	19
Figure 17	The global view of mesh of A2 wheel model	21
Figure 18	The local view of mesh of A2 wheel model	21
Figure 19	The flow chart of the pressure-based solver [24]	26
Figure 20	The flow chart of ITA (Iterative Time Advancement) scheme for segregated solver [24]	28
Figure 21	The flow chart of NITA (Non-Iterative Time Advancement) scheme [24]	29
Figure 22	Boundary name of domain of A2 wheel model in ANSYS Fluent	30
Figure 23	The grooved tire of hydroplaning model	35
Figure 24	The water inlet is placed at 1d in front of wheel	36
Figure 25	The bottom view of hydroplaning model	36
Figure 26	The comparison of CL of A2 wheel model	40
Figure 27	The comparison of CD of A2 wheel model	40
Figure 28	The comparison of pressure coefficient plot of A2 wheel model at central line	41
Figure 29	Schematic picture of an isolated wheel under rotation	42
Figure 30	The wake flow behind the A2 wheel	43
Figure 31	The wake flow behind the A2 wheel on side view	43
Figure 32	The pressure contour of bottom of tire when tire moving forward under 50 km/h and 20 mm height water layer	44
Figure 33	The pressure contour of x-y plane of domain when tire moving forward under 50 km/h and 20 mm height water layer	44
Figure 34	The water volume fraction contour of bottom of tire when tire moving forward under 50 km/h and 20 mm height water layer	45
Figure 35	The water volume fraction contour of longitudinal and lateral plane of domain and ground when tire moving forward under 50 km/h and 20 mm height water layer	45
Figure 36	The velocity contour on y-z plane at speed of 50 km/h	46
Figure 37	The velocity contour on x-y plane at speed of 50 km/h	47
Figure 38	The turbulence intensity contour on y-z plane at speed of 50 km/h	47
Figure 39	The turbulence intensity contour on x-y plane at speed of 50 km/h	47
Figure 40	The vorticity on the view of y-z plane at speed of 50 km/h	48
Figure 41	The vorticity on the view of x-y plane at speed of 50 km/h	48
Figure 42	The Q-criteria on view of y-z plane at speed of 50 km/h	49
Figure 43	The Q-criteria on view of x-y plane at speed of 50 km/h	49
Figure 44	The lift force plot compared with the results of Kim, T. W. et al [17] [18]	50
Figure 45	The time evolution of lift force of Vincent et al [19] for smooth tread pattern (T1) and 50 km/h speed	51
Figure 46	Time evolution of lift force for 10 km/h under case 1 (a) and case 2 (b)	52
Figure 47	Time evolution of lift force for 20 km/h under case 1 (a) and case 2 (b)	52
Figure 48	Time evolution of lift force for 30 km/h under case 1 (a) and case 2 (b)	52
Figure 49	Time evolution of lift force for 40 km/h under case 1 (a) and case 2 (b)	53
Figure 50	Time evolution of lift force for 50 km/h under case 1 (a) and case 2 (b)	53
Figure 51	Time evolution of lift force for 60 km/h under case 1 (a) and case 2 (b)	53
Figure 52	Time evolution of lift force for 70 km/h under case 1 (a) and case 2 (b)	54
Figure 53	The results of lift force compare with case 1 and case 2	55
Figure 54	Time evolution of lift force in 10 and 20 km/h under implicit and explicit volume fraction scheme	56
Figure 55	Time evolution of lift force in 30 and 40 km/h under implicit and explicit volume fraction scheme	56
Figure 56	Time evolution of lift force in 50 and 60 km/h under implicit and explicit volume fraction scheme	57
Figure 57	Time evolution of lift force in 70 and 80 km/h under implicit and explicit volume fraction schemes	57
Figure 58	The results of lift force compared with implicit and explicit schemes	58

List of Tables
Table 1	B2 wheel during stationary and rotation [10]	9
Table 2	The A2 wheel model mesh setting	20
Table 3	Boundary conditions of A2 wheel model in ANSYS Fluent	30
Table 4	Numerical setup of A2 wheel model in ANSYS Fluent	30
Table 5	The hydroplaning model mesh setting	37
Table 6	The boundary conditions and numerical setup of hydroplaning model with inflation	38
Table 7	The boundary conditions and numerical setup of hydroplaning model without inflation	39

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