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系統識別號 U0002-0309201214462900
中文論文名稱 大雨影響下圓柱體流場之數值模擬
英文論文名稱 Numerical Simulation of Circular Cylinder Vortex Flow under Heavy Rain Effects
校院名稱 淡江大學
系所名稱(中) 航空太空工程學系碩士班
系所名稱(英) Department of Aerospace Engineering
學年度 100
學期 2
出版年 101
研究生中文姓名 陳柏禕
研究生英文姓名 Po-Yi Chen
學號 699430145
學位類別 碩士
語文別 英文
第二語文別 中文
口試日期 2012-07-17
論文頁數 68頁
口試委員 指導教授-宛同
委員-洪勵吾
委員-湯敬民
中文關鍵字 圓柱  大雨  二相流  表面粗糙度  空氣動力學 
英文關鍵字 Circular cylinder  Heavy Rain  Two Phase Flow  Surface Roughness  Aerodynamics 
學科別分類 學科別應用科學航空太空
中文摘要 近年來,由於氣候變化的影響,極端氣候的現象比過去更為頻繁,如:暴雨、強風、颱風...等,由於考慮到圓柱結構放置在戶外的情況下,我們在設計外型的階段時必須將惡劣氣候的條件考慮進去。因此,對於在大雨影響下柱體尾流情形的數值模擬更為重要且不可忽視。利用商用軟體FLUENT於不同數量和外型的柱體和大雨機制的模擬。
在此篇論文中,我們首先對於在雷諾數為100和200流體流經單一圓柱後的尾流分離做數值模擬。接下來,在對於雷諾數為200的情況下兩個相同直徑前後串聯的圓柱做模擬。透過成功的模擬前面3個不同的情況,我們對於接下來的研究更有信心。模擬雷諾數為2.5×104~1.0×105的LP-810纜線在大雨下的情形,則是採用FLUENT內二相流(Two-Phase Flow)的DPM模組(Discrete Phase Model)和改變圓柱的表面出糙度來計算空氣動力特性。雖然模擬出的結果和實驗值不完全相同,但是我們成功的模擬出LP-810在晴空狀態及大雨影響下阻力係數的變化趨勢。本研究在對於工業用纜線在側風及大雨影響條件下的空氣動力特性分析是非常有用的。
英文摘要 In recent years, due to the impact of climate changing, the phenomenon of extreme weather is more frequently compared to the past, such as heavy rain, strong wind, typhoon-weather conditions etc. For the cylindrical structure being located outdoors, we must put these severe weather influences into considerations in the stage of geometry design. Therefore, the importance of numerical simulation for circular cylinder vortex flow under the heavy rain effects can never be neglected.
In this work, we first investigated the vortex shedding behind a circular cylinder at Re=100 and 200. Secondly, two circular cylinders in tandem arrangement at Re=200 are simulated also. Through the simulation of these three cases successfully, we will be more confident for the following research. For the heavy rain simulations, the two-phase flow approach plus the wall film mechanism on the body surface are implemented for LP-810 cable and at Re=2.5×104 to 1.0×105. Although the numerical results for the cable under the heavy rain effects show that aerodynamic degradation was not perfectly match to the experimental data, the correct tendency of the cable aerodynamic performance under both the clear weather and heavy rain situations are simulated successfully. The proposed simulation results will be quite useful to understand the industrial suspension cable’s behavior in cross wind and heavy rain conditions.
論文目次 Contents

Abstract I
Contents III
List of Tables IV
List of Figures V
Nomenclatures VII
Chapter 1 Introduction 1
Chapter 2 Research Background 4
Chapter 3 Characteristics of Rain 9
Chapter 4 Numerical Modeling 13
4-1 Geometry Model Construction 13
4-2 Grid Generation 16
4-3 Flow Solver 20
4-4 Turbulence Modeling 23
4-5 Discrete Phase Model 25
4-6 Surface Roughness 29
4-7 Heavy Rain Physics 31
Chapter 5 Results and Discussion 34
Chapter 6 Conclusions 55
References 57


List of Tables

Table 5-1 The average drag coefficients and Strouhal number for a single circular cylinder at Re=100 and Re=200 [9] 38
Table 5-2 Numerical results for a single circular of pressure and viscous drag coefficient at Re=100 and 200 39
Table 5-3 The Strouhal number and mean drag coefficients for two circular cylinders in tandem arrangement at Re=200 40
Table 5-4 Numerical results for two circulars of pressure and viscous drag coefficient at Re=200 41
Table 5-5 The drag coefficient of the LP-810 cable for different turbulence models 43
Table 5-6 The comparison of the drag coefficient for the cable and smooth circular cylinder with V=10 m/s and V=40 m/s 46
Table 5-7 Heavy rain conditions 47
Table 5-8 Numerical results for cable LP-810 of drag coefficients degradation percentage 49
Table 5-9 Experiment results for cable LP-810 of drag coefficients degradation percentage [19] 49
Table 5-10 Numerical results for cable LP-810 of viscous drag coefficients degradation percentage 51
Table 5-11 Numerical results for cable LP-810 of pressure drag coefficients degradation percentage 51

List of Figures

Figure 2-1 Regimes of fluid flow over a circular cylinder [4] 7
Figure 2-2 Normalized distribution of the total data sample [16] 10
Figure 4-1 Computational domain of a single circular cylinder 14
Figure 4-2 Computational domain of two circular cylinders in tandem arrangement 14
Figure 4-3 The geometric model of cable compared to Kikuchi's Model [19]. (a) Kikuchi's Model (LP-810) and (b) present numerical model 15
Figure 4-4 Computational domain of cable LP-810 15
Figure 4-5 Mesh of the entire calculation domain for a single cylinder 17
Figure 4-6 Near mesh of a single circular cylinder 17
Figure 4-7 Mesh of the entire calculation domain for two cylinders 18
Figure 4-8 Near mesh of the downstream cylinder 18
Figure 4-9 Mesh of the entire calculation domain for cable LP-810 19
Figure 4-10 Near mesh of cable LP-810 19
Figure 4-11 Physics of splashing, momentum, heat, and mass transfer for the Wall-Film [20] 27
Figure 5-1 (a) Vorticity (b) Pressure field at Re=100 35
Figure 5-2 (a) Vorticity (b) Pressure field at Re=200 36
Figure 5-3 Lift and drag coefficient for a single cylinder at Re=100 37
Figure 5-4 Lift and drag coefficient for a single cylinder at Re=200 37
Figure 5-5 Pressure and viscous drag for a single cylinder at Re=100 and 200 38
Figure 5-6 (a) Vorticity and (b) Pressure contours for two circular cylinders in tandem arrangement 40
Figure 5-7 The averaged drag coefficient for LP-810 cable numerical and experimental results..................................................................................42
Figure 5-8 Drag coefficient for cable LP-810 numerical result comparing to experimental data 42
Figure 5-9 Pressure contours for different free stream velocities with LWC=0 g/m3 44
Figure 5-10 Vorticity contours for different free stream velocities with LWC=0 g/m3 45
Figure 5-11 Local view of rain droplets impingement 48
Figure 5-12 Drag coefficient for cable LP-810 numerical and experimental results 50
Figure 5-13 Viscous drag coefficient for different wind speed with LWC=0 g/m3 and LWC=9.23 g/m3 52
Figure 5-14 Pressure drag coefficient for different wind speed with LWC=0 g/m3 and LWC=9.23 g/m3 52
Figure 5-15 Pressure contours for different free stream velocity with LWC=9.23 g/m3 53
Figure 5-16 Vorticity contours for different free stream velocity with LWC=9.23 g/m3 54
參考文獻 References

[1] Strouhal, V., “Uber enie Besondere Art der Tonerregung,” Annalen der Physik und Chemie(Leipzig) , 1878, pp. 217-251.
[2] Von Karman, T., “Uber den Mechanismuss des Windersstandes den ein bewegter Korper in einen Flussigkeit Erfahart,” Nachrichten der k. Gesellschaft der Wissenschaften zu Gottingen, 1914, pp.547-556.
[3] Roshko, A., “On the Wake and Drag of Bluff Bodies,” Journal of the Aeronautical Science, 1955, Vol. 22, pp. 144-142.
[4] Lienhard, J.H., “Synopsis of Lift, Drag, and Vortex Frequency Data for Rigid Circular Cylinders,” Washington State University, College of Engineering, Research Division Bulletin, pp. 300, 1966.
[5] Zdravkovich, M.M., “Review of Flow Interference between two Circular Cylinders in Various Arrangement,” ASME Journal of Fluids Engineering, 1977, Vol. 99, pp. 618-633.
[6] Bearman, P.W. and Wadcock, A.J., “The Interaction between a pair of Circular Cylinder Normal to a Stream,”Journal of Fluid Mechanics, 1973, Vol. 61, pp. 499-511.
[7] Williamson, C.H.K., “Evolution of a Single Wake behind a pair of Bluff Bodies,”Journal of Fluid Mechanics, 1985, Vol. 159, pp. 1-18.
[8] Kim, H.J. and Durbin, P.A., “Investigation of the Flow between a pair of Circular Cylinders in the Flopping Regime,”Journal of Fluid Mechanics, 1988, Vol. 196, pp. 431-448.
[9] Meneghini, J.R., Saltara, F., Siqueira, C.L.R., Ferrari, Jr. J.A.,“Numerical Simulation of Flow Interference between Two Circular Cylinders in Tandem and Side-by-Side Arrangements,” Journal of Fluids and Structures, 2001, Vol. 15, pp. 327 - 350.
[10] Mittal, S., Kumar, V. and Raghuvanshi, A., “Unsteady Incompressible Flows past Two Cylinders in Tandem and Staggered Arrangements [J],”International Journal for Numerical Methods in Fluids, 1997, 25(11), pp. 1415-1444.
[11] Sharman, B., Lien, F.S. and Davidson, L. et al., “Numerical Predictions of Low Reynolds Number Flows over Two Tandem Circular Cylinders [J],“International Journal for Numerical Methods in Fluids, 2005, 47(5), pp. 423-447.
[12] Chou, C.J., “Aerodynamic Investigation of High-Lift Airfoil Under the Influence of Heavy Rain Effects,”M.S. thesis, Tamkang University, June 2011, pp. 29-36.
[13] Marshall, J. S. and Palmer, W. M., “The Distribution of Rain Drop in Size,” Journal of Meteorology, Vol. 5, 1948, pp. 165-166.
[14] Ulbrich, C. W., “Natural Variations in the Analytical Form of the Raindrop Size Distribution,” Journal of Applied Meteorology, Vol. 22, 1983, pp. 1764-1775.
[15] Willis, P. T., “Functional Fits to Some Observed Drop Size Distributions and Parameterization of Rain,” Journal of Atmospheric Sciences, Vol. 41, No. 9, 1984, pp. 1648-1661.
[16] Willis, P. T. and Tattleman, P., “Drop-size Distributions Associates with Intense Rainfall,” Journal of Applied Meteorology, Vol. 28, 1989, pp. 3-14.
[17] Zhao, M., Cheng, L., Teng, B., and Liang, D., “Numerical Simulation of Viscous Flow past Two Circular Cylinders of Different Diameters,”Applied Ocean Research, 2005, Vol. 27, pp. 39-55.
[18] Dehkordi, B.G., Moghaddam, H.S., Jafari, H.H., “Numerical Simulation of Flow over two Circular Cylinders in Tandem Arrangement,”Department of Mechanical Engineering, 2011, Vol. 23, pp. 114-126.
[19] Kikichi, N. and Matsuzaki, Y., “Aerodynamic Drag of New-design Electric Power Wire in a Heavy Rainfall and Wind,” Journal of Wind Engineering and Industrial Aerodynamics, Vol. 91, 2003, pp.41-51.
[20] FLUENT's User Guide.
[21] Cebeci, T. and Bradshaw, P., Momentum Transfer in Boundary Layers, Hemisphere Publishing Corporation, New York, 1977.
[22] Dunham, R.E., Jr., “The Potential Influence of Rain on Airfoil Performance,” Von Karman Institute for Fluid Dynamics, 1987.
[23] Markowitz, A.M., “Raindrop Size Distribution Expression,” Journal of Applied Meteorology, Vol. 15, 1976, pp. 1029-1031.
[24] Mahir, N. and Altac, Z., “Numerical Investigation of Convective Heat Transfer in Unsteady Flow past Two Cylinders in Tandem Arrangements [J],”International Journal of Heat and Fluid Flow, 2008, 29(5), pp. 1409-1418.
[25] Saltara, F., “Numerical Simulation of the Flow about Circular Cylinders,”Ph.D. thesis, EPUSP University of Sao Paulo, Brazil (in Portuguese), 1999.
[26] Williamson, C.H.K., “2-D and 3-D Aspects of the Wake of a Cylinder, and Their Relation to Wake Computations [J],”Vortex Dynamics and Vortex Methods, 1991, Vol. 28, pp. 719-751.
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