(3.235.191.87) 您好!臺灣時間:2021/05/13 13:54
字體大小: 字級放大   字級縮小   預設字形  
回查詢結果

詳目顯示:::

: 
twitterline
研究生:陳鴻嵐
研究生(外文):Hung Lan Chen
論文名稱:均勻來流中二維梯形鈍體紊流流場之數值探討
論文名稱(外文):Numerical Investigations on Flow Around a Two-Dimensional Trapezoidal Bluff Body
指導教授:方富民方富民引用關係
指導教授(外文):Furman F.M. Fang
學位類別:碩士
校院名稱:國立中興大學
系所名稱:土木工程學系
學門:工程學門
學類:土木工程學類
論文種類:學術論文
論文出版年:2001
畢業學年度:89
語文別:中文
論文頁數:108
中文關鍵詞:計算風工程大渦模擬
外文關鍵詞:Computational Wind EngineeringLarge Eddy Simulation
相關次數:
  • 被引用被引用:3
  • 點閱點閱:137
  • 評分評分:系統版面圖檔系統版面圖檔系統版面圖檔系統版面圖檔系統版面圖檔
  • 下載下載:10
  • 收藏至我的研究室書目清單書目收藏:1
鈍體在風域中的受風效應之分析一向為建築研究領域裡重要的一環,為了獲取結構物承受之風荷重,以為推算其相應動態反應之依據,現行的方法多採用簡化狀況的風洞試驗配合實場量測資料而得之風函數。但此類風函數並不足以提供實際情況中複雜幾何與流力狀況下準確之風荷重數據,如結構物之造型特殊、風場中存在著其他建築物、或當來流屬非典型風況時,應用此類函數於設計中將導致誤差,甚至造成不保守的結果。
本研究旨在以微可壓縮流加大渦模擬的方法,計算均勻來流中二維梯形鈍體紊流流場。研究中以雷諾數為107,在均勻來流下流經梯形斷面,變化幾何形狀與風攻角探討流場特性之相關特性,期藉流場之模擬系統化地探討梯形結構物受到風力作用所引起的氣動行為。
研究結果指出,風攻角對於流場的速度場及風力係數的影響大於幾何斷面的影響。當流場雷諾數大於105後,流場已具備不變性。平均阻力係數 值隨著幾何張角之增大而增大,而平均昇力係數 亦是隨著來流攻角之遞增而遞增,在攻角為零時有最小之擾動阻力係數 與擾動昇力係數 值。而在低攻角下(-2O≦α≦+2O)昇力係數之頻譜受梯形截面上下方之渦散剝離頻率影響且出現單一主頻;一般而言當幾何角為15度時有較佳之風力效應,但當風攻角較大時會有較大之昇力攝動量需謹慎注意。
Investigation on flow around a bluff body has been an important subject in building research. To evaluate the dynamic response of a structure, the flow effects on the body and related flow characteristics are necessary during the design stage. Nowadays, there are mostly obtained by wind tunnel model testings. However, the accuracy of the experimental results usually suffers from scale effect. Besides, the achievement of the complete flow data is generally costly. Therefore, the application of high-speed computation in flow simulation becomes an important way of the analyses.
The objective of the study is to investigate numerically the turbulent flow around a two dimensional trapezoidal bluff body. In the study, a weakly-compressible-flow method incorporated with a space-average large-eddy-simulation technique is adopted. By varying the shape of the trapezoidal deck section and the attack angle of the approaching flow, the resulting surrounding flow characteristics and the wind effect on the body are assessed.
Results show that the major influence of the flow characteristics is the approaching-flow attack angle. As the geometric angle of the trapezoidal body increases, the mean drag coefficient also increases. On the other hand, as the attack angle increases, the mean lift coefficient also increases. When the angle of attack is zero the root-mean-square values of the drag and lift coefficient become minimum. When the attack angle is small, the spectrum of lift coefficient shows a single peak. Generally, a better wind effect on the body is obtained as the geometric angle equals 15o. However, it may result in a large fluctuating lift force at a large attack angle. Finally, The general characteristics of the flow remains unchanged as Reynolds number exceeds about 105.
目錄
中文摘要 I
英文摘要 II
目錄 III
圖目錄 V
表目錄 VIII
符號說明 IX
第一章、緒論 1
1-1、前言 1
1-2、研究動機 2
1-3、研究目的 2
第二章、理論背景及相關研究 4
2-1、背景說明 4
2-2、相關研究 4
第三章、數值模擬 10
3-1、前言 10
3-2、計算區域大小之決定 10
3-3、網格設計 11
3-4、流場模擬 11
3-4-1、數值方法 11
3-4-2、邊界條件 16
3-4-3、起始條件 17
第四章、結果分析 18
4-1、模式驗證 18
4-2、流場結果分析 20
4-2-1、幾何形狀對流場的影響 20
4-2-2、來流攻角對流場的影響 21
4-3、渦度場結果分析 21
4-4、時平均流場中再接觸點位置分析 22
4-5、風力係數結果分析 24
4-6、頻譜結果分析 25
4-7、雷諾數變化對流場的影響 26
4-8、討論 27
第五章、結論與建議 30
5-1、結論 30
5-2、建議 31
參考文獻 32
圖目錄
圖1-1 二維梯形截面受風簡圖 37
圖3-1 計算區域簡圖 38
圖3-2 流場計算網格圖 39
圖3-3 流場計算數值透式邊界條件說明圖 44
圖3-4 流場計算數值不透式邊界條件說明圖 45
圖3-5 流場計算典型之速度歷時圖 46
圖4-1 尾流區中心線上時平均之順風向速度分佈與試驗值比較圖 47
圖4-2 柱體表面時平均風壓分佈計算值與試驗值比較圖 48
圖4-3 不同攻角下長時段平均流場速度等值圖(θ=15°) 49
圖4-4 不同攻角下長時段平均流場速度等值圖(θ=30°) 52
圖4-5 不同攻角下長時段平均流場速度等值圖(θ=45°) 55
圖4-6 不同攻角下長時段平均流場速度等值圖(θ=60°) 58
圖4-7 不同攻角下長時段平均流場速度等值圖(θ=75°) 61
圖4-8 不同攻角下長時段平均流場速度等值圖(θ=90°) 64
圖4-9 不同攻角下長時段平均流線圖(θ=15°) 67
圖4-10 不同攻角下長時段平均流線圖(θ=30°) 70
圖4-11 不同攻角下長時段平均流線圖(θ=45°) 73
圖4-12 不同攻角下長時段平均流線圖(θ=60°) 76
圖4-13 不同攻角下長時段平均流線圖(θ=75°) 79
圖4-14 不同攻角下長時段平均流線圖(θ=90°) 82
圖4-15 一渦散週期中四個典型時間渦度等值圖 85
圖4-16 不同攻角、幾何張角下與梯形斷面上板再接觸點長度關係.99
圖4-17 不同攻角、幾何張角下與梯形斷面下板再接觸點長度關係 99
圖4-18 不同攻角、幾何張角下與 關係圖 100
圖4-19 不同攻角、幾何張角下與 關係圖 100
圖4-20 不同攻角、幾何張角下與 關係圖 101
圖4-21 不同攻角、幾何張角下與 關係圖 101
圖4-22 不同幾何角下攻角α= - 8°之昇力係數頻譜圖 102
圖4-23 不同幾何角下攻角α= - 6°之昇力係數頻譜圖 102
圖4-24 不同幾何角下攻角α= - 4°之昇力係數頻譜圖 102
圖4-25 不同幾何角下攻角α= - 2°之昇力係數頻譜圖 103
圖4-26 不同幾何角下攻角α= 0°之昇力係數頻譜圖 103
圖4-27 不同幾何角下攻角α= + 2°之昇力係數頻譜圖 103
圖4-28 不同幾何角下攻角α= + 4°之昇力係數頻譜圖 104
圖4-29 不同幾何角下攻角α= + 6°之昇力係數頻譜圖 104
圖4-30 不同幾何角下攻角α= + 8°之昇力係數頻譜圖 104
圖4-31 不同雷諾數下長時間平均速度等值圖(θ=60°) 105
圖4-32 不同雷諾數下長時間平均速度流線圖(θ=60°) .107
表目錄
表4-1 計算值與實驗及其他計算值之比較 19
表4-2 幾何角與風攻角對上版再接觸點發生之關係 23
表4-3 幾何角與風攻角對下版再接觸點發生之關係 23
表4-4 風攻角與幾何張角對上下板面頻率之分布 26
表4-5 雷諾數與各類係數之關係 26
參 考 文 獻
[1] Basara, B. and Younis, B. A. (1992) " Progress in the Prediction of Turbulent Wind Loading on Buildings," J. Wind Engg. And Ind. Aerod. , Vol.41and 44,pp. 2863-2874.
[2] Bearman, P. W. and Truman, D. M. (1972) " An Investigation of the Flow Around Rectangular Cylinder, " Aero. Quartely, Vol.23, pp.229-237.
[3] Benodekar, R. W., Goddard, A. J. H., Gosman , A. D., and Issa, R. I. (1985), " Numerical Ptrediction of Turbulent Flow over Surface-Mounted Ribs, "AIAA J., Vol.23, No. 3, pp359-366.
[4] Brown, G. L. (1974), " On Density Effects and Large Structure in Turbulent Mixing Layers, " J. Fluid Mech ., Vol.64,part 4 ,pp775-816.
[5] Castro, G. L. and Roshko, A. (1974), " The Flow Around a Surface Mounted Cube In Uniform and Turbulent Streams, " J. Fluid Mech., Vol.79, part2, pp.307-335.
[6] Cherry, N. J., Hillier, R. and Latour, M. E. M. P.(1984), " Unsteady Measurement in a Separated And Reattaching Flow, " J. Fluid Mech., Vol.144,pp.13-46.
[7] Clark, R. , Ferziger, J. H. and Reynolds, W. C(1979) , "Evaluation of Subgrid-Scale Models Using Accurated Simulated Turbulent Flow ," J. Fluid and Mech , Vol.91 , Part1,pp.1-16.
[8] Crabb, D., Durao, D. F. G. and White, J. H.(1977), "Velocity Characteristic in the Vicinity of a Two Dimensional Rib, " Proceeding of the 4th Brazilian Congress on Mechanical Eng., Florianopolis Brazil, pp.47-58.
[9] Crow, S. C., Heitor and Champagne, F. H. (1971), " Orderly Structure in Jet Turbulence," J. Fluids Mech, Vol.48, Part3, pp.547-591.
[10] Deng , G. B. , Piquet J. , Queutey P. and Visonneau M.(1994) , Ŗ-D Computations of Unsteady Flow Past a Square Cylinder with the Baldwin-Lomax Model ," J. Fluid and Structures , Vol.8 , pp.663-680.
[11] Dimaczek G., Tropea,C. and Wang,A.B.(1989) , " Turbulent Flow Over Two-Dimensional, Surface-Mounted Obstacles: Plane and Axisymmetric Geometries," in:H.-H.E.Fielder(Eds.),Advanced in Turbulence 2,Springer,Heidelberg , pp.19-32.
[12] Durao, D. F. G., Heitor, M. V. and Pereira, J. C. F. (1988), " Measurement of Turbulent and Periodic Flows Around A Square Cross-Section Cylinders," Experiments in Fluids, Vol.6, pp.298.
[13] Enger, L. (1986), " A Higher Order Clousure Model Applied to Dispersion in a Convective PBL. " Atmospheric Environment, Vol.20, pp.879-894.
[14] Fang, Fuh-Min (1989), " Flow Characteristics in Three-Dimensional Channel Contractions," Ph.D. Dissertation, University of Minnesota, USA.
[15] Fang, Fuh-Min (1997), " On the Flow Around a Vertical Porous Fence, " J. Wind Engg. And Ind.Aerod.,Vol.67and 68, pp.415-424.
[16] Fang, Fuh-Min , Jong,W.D. J.J.(1997)" Unsteady Turbulent Flow Past Solid Fence, " J.Hydraulic Engg. , ASCE,,Vol.123, pp.560-565.
[17] Good, M.C.and Joubert, P.N. ,(1968)" The Form of Two-Dimensional Bluff-Plates Immersed in Turbulent Boundary Layers, " J. Fluid Mech. ,Vol.31,Part 3 , pp.547-582
[18] Gupta,V.P. and Raju G. R.(1986), " Separated Flow in Lee of Solid and Porous Fences , " J. Hydraulic Engg., ASCE, Vol.113,No.10.
[19] Hanson, T., D. M. and Wilson,C.B. (1984)" Numerical Modeling of Wind Flow Over Building in Two Dimension Turbulent , "Int’l J. Numerical Methods in Fluid ,Vol.4, pp.25-41.
[20] Han, T., (1989)" Computational Analysis of Three-Dimensional Turbulent Flow Around a Bluff-Plates in Ground Proximity, "AIAA J.,Vol.27,No.9 , pp.1231-1219.
[21] Kawahara M. and Hirano H. (1985),Finite Element Analysis of Wind Force to Structures, Bulletin of Chuo University
[22] Kline, S.J., Renolds, W.C., Schrab, W.F.A., and Runstadler, P.W. (1967) ," The Structure in Turbulent Boundary Layers , "J. Fluid Mech . , Vol.30,Part 4 , pp.741-773.
[23] Lane, J. C. and Loehrke , R.I. (1980), "Leading Edge Separation from a Blunt Plate at Low Reynolds Number, " J. Fluids Engg.,Trans. ASME, Vo;102, pp.495-496.
[24] Lee B. E. (1975), "The effect of Turbulence on the Surface Pressure Field of a Square Prism ," J. Fluid Mech ., Vol.69 , part 2 , pp.263-282.(1975)
[25] Lee B. E. (1990)," Some Observations of the Effect of Aspect Ratio on the Influence of Turbulence on the Drag of Rectangular Cylinders," J. Wind Engg. and Ind. Aero., Vol.33 ,pp.107-111.
[26] MacCormak, R.W. (1969), ," The Effect of Viscosity in Hyper-Velocity Impact Cratering ," AIAA PAPER, NO.69-354.
[27] Mathews, E.H. (1987)," Prediction of the Wind-Generated Pressure Distribution Around Buildings," J.Wind Engg. and Ind. Aerod. ,Vol. 25, pp219-228.
[28] Murakami, S. and Mochida, A.(1988)," 3-D Numerical Simulation of Airflow Around a Cubic Model by Means of the K-εModel ," J. Wind Engg. and Ind. Aerod. , Vol. 31, pp283-303.
[29] Murakami, S. and Mochida, A. and Hayashi, Y. (1990),"Examining the K-ε Model by Means of A Wind Tunnel Test and Large-Eddy Simulation of the Turbulence Structure Around a Cube ," J. Wind Engg. and Ind. Aerod . , Vol. 35, pp87-100.
[30] Murakami, S. and Mochida, A. and Hayashi, Y. and Sakamoto, S.(1992), "Numerical Study on Velocity Pressure Field and Wind Forces for Bluff Bodies by K-ε, ASM and LES ," J.Wind Engg. and Ind. Aerod. , Vol. 41-44, pp2481-2852.
[31] Murakami, S. and Mochida, A. (1995) ," On Turbulent Vortex Shedding Flow Past 2D Square Cylinder Predicted by CFD ," J. Wind Engg. and Ind. Aerod. , Vol. 54/55-, pp191-211.
[32] Nakamura Y. and Nakashima, M. (1986) " Vortex Excitation of Prisms with Elongated Rectangular, H and ├ Cross-section," J. Fluid Mech. , Vol. 163,pp.149-169.
[33] Nakamura Y. and Ohya, Y. (1989) " The effect of turbulence on the mean flow past two-dimensional rectangular cylinders ,"J. Fluid Mech.149,255-273
[34] Nakamura Y. and Ozono , S . (1987) " The effect of turbulence on a separated and reattaching flow. "J. Fluid Mech.178,477-490
[35] Nakamura Y. (1993) " Bluff Body Aerodynamics and Turbulence, "J. Wind Engg. and Aerod. , Vol.49,pp.65-78
[36] Okajima, A. (1982), " Strouhal Numbers of Rectangular Cylinders ," J. Fluid Mech., Vol.123, pp. 279-398.
[37] Okajima, A. (1990), " Numerical Simulation Strouhal of Flow Around Rectangular Cylinders ," J. Fluid Engg. and Ind. Aero., Vol.133, pp. 171-180.
[38] Roshko, A. (1954) "On The Development of Turbulent Wake from Vortex Street, " NACA Report NO.1191.
[39] Santo H.P. and Branco , (1989), "Wind Force on Bridges-Numerical Vs. Experimental methods "J.Wind Engg and Aerod. ,Vol 32,pp 145-159
[40] Schofield, W. H. and Logan, E. (1990), " Turbulent Shear Flow over Surface Mounted Obstacles," J. Fluids Engg. , Trans. ASME,Vol. 112, pp. 376-385.
[41] Shah, K. B., and Freziger, J. H. (1993), " A Fluid Mechanician View of Wind Engineering : Large Eddy Simulation of Flow Past a Cubic Obstacle ," J. Wind Engg. and Ind. Aerod. ,V. 67-88 , pp. 211-224.
[42] Song, C. C. S., and Yuan , M. (1990), " Simulation of Vortex Shedding Flow about a Circular Cylinder at High Reynolds Number ," J. Fluid Engg. ,Trans. ASME, Vol. 112.
[43] Smagorinsky, J. (1963), " General Circulation Experiments with the Primitive Equations ," Month Weather Review , Vol.93, No.99, pp.99-164.
[44] Tamura, T. and Kuwahara, K. (1990), " Numerical Study of Aerodynamic Behavior of a Square Cylinder ," J. Wind Engg. and Ind. Aerod. ,V.33 ,pp. 161-170.
[45] Zhu ,B. , Chen , D.P.and Shang J.S.(1993) " Wind Load on Bridge Deck by the penalty —Hybrid/mixed Finite Element Method " J. Wind Engg and Aerod. ,Vol.50,pp31-38
[46] 蔡惠文(1996)," 均勻來流中二維矩柱支流場模擬",中興大學土木工程研究所碩士論文。
[47] 陳文良(1997),"雙矩形建築鄰近風場之數值研究",中興大學土木工程研究所碩士論文。
[48] 許文雄(2000), " 方形截面建築物問紊流流場之數值模擬",中興大學土木工程研究所碩士論文。
[49] 方富民等(2000)," 高鐵台中烏日站區聯外道路系統跨越旱溪拱承協張橋風洞試驗研究",研究結果報告書,財團法人中興土木科技發展文教基金會。
QRCODE
 
 
 
 
 
                                                                                                                                                                                                                                                                                                                                                                                                               
第一頁 上一頁 下一頁 最後一頁 top
系統版面圖檔 系統版面圖檔