https://scholars.lib.ntu.edu.tw/handle/123456789/86161
標題: | 行政院國家科學委員會專題研究計畫成果報告:防風設施防風效果及環境風場之數值與實驗研究﹝2/2﹞ | 作者: | 張倉榮 | 關鍵字: | 防風設施;減風效果;環境流場;計算流體動力學;風洞試驗;Windbreaks;Shelter Efficiency;Wind Flows;Computational Fluid Dynamics;Wind Tunnel Experiment | 公開日期: | 2003 | 出版社: | 臺北市:國立臺灣大學生物環境系統工程學系暨研究所 | 摘要: | 本研究為二年期研究計畫,自90 年度執 行到92 年度為止,進行防風設施防風效果與 環境風場的數值模擬與風洞試驗。第一年度 (90 年)計畫的主要目的為建立一套計算防風 設施設環境風場的CFD 數值模式,並以此模 式進行數值境況模擬,以期能了解防風設施 在不同幾何形狀、水平剖面透風度、垂直剖 面透風度、氣象因素及周遭環境地形等條件 下之減風效果,並探討最佳減風效果與風之 相對關係。本研究選擇大尺度漩渦模擬(LES) 代表防風設施的亂流狀況,並將之納入控制 方程式-納維-史托克方程式中。研究中為使 模擬結果更能接近於實際防風設施氣流流動 狀況,採用邊界閉合座標法,將移動之不規 則物理平面轉換成規則之計算平面,以利數 值計算。模式採非交錯格網分布,即流速及 壓力在同一格點上,以有限差分法將納維- 史托克方程式離散後以顯式法解之,求解過 程中乃採每一格點之質量守恒之差值,作為 該點壓力之修正參數,直至整個流場均滿足 質量守恒。本研究第二年度之主要目的則為 進行風洞試驗方法瞭解防風設施環境風場。 此風洞為一低風速、開放、吸入式之中型邊 界層風洞,以實際量測資料進行模式調整與 驗證,並探討第一年的數值模擬所得到的各 種不同幾何形狀、水平剖面透風度、垂直剖 面透風度等條件下之減風效果,並進行最佳 減風效果與風之相對關係研究。 本數值及風洞試驗成果顯示,九種幾何 形狀的減風係數之差異性皆在10%以內,故 防風設施的幾何形狀對減風效果並無顯著影 響。水平與垂直剖面透風度則對減風效果有 重大影響,而防風設施透風度以40%為最佳 設計。因此,未來只要將透風度控制在40% 左右,防風設施幾何形狀的設計上可有更大 的自由度,搭配當地的自然景觀,達成工程 生態化的目標。 The study is a NSC two-year project (2001-2003) entitled “Numerical and experimental investigations on shelter effectiveness and wind flow near windbreaks”. The main objective of this study is to numerically as well as experimentally investigate the shelter effectiveness and wind flows near windbreaks. A combination of numerical scenario simulations and wind tunnel experiments of windbreak flows, considering the effects of the geometric shape, porosity of horizontal profile, porosity of vertical profile, meteorological conditions, and surrounding terrain on shelter effectiveness, has been conducted. In the first year, a two-dimensional dynamic windbreak model is developed. The Large Eddy Simulation (LES) is selected as the turbulence model in the study, which is incorporated in the governing equations: Navier-Stokes equations. A series of numerical scenario simulations of windbreak flows are conducted so that the effects of the geometric shape, porosity of horizontal profile, porosity of vertical profile, meteorological conditions, and surrounding terrain on shelter effectiveness can be obtained. To simulate windbreak flows more accurately, the boundary-fitted coordinate is employed in the study to fit the irregular greenhouse boundary by transforming the complex physical domain onto the simple numerical domain. The up-winding finite difference method with explicit scheme is used to solve the Navier-Stokes equations. In the second year, an experimental procedure for a medium size boundary layer wind tunnel is also carried out. The wind tunnel results are used to demonstrate the mechanism of wind reduction of windbreaks and to verify the first-year numerical results. The report demonstrates the results of this two-year project. The results include CFD numerical model establishment, model verification with reliable measured data, setup pf wind tunnel experiments, and the effects of the geometric shape, porosity of horizontal profile, porosity of vertical profile, meteorological conditions, and surrounding terrain on shelter effectiveness. The 40% porosity shelter gives the most effective wind reduction effect. The results of the numerical scenario simulations and wind tunnel experiments can provide the essential information of the best-designed windbreaks from the viewpoint of ecology. |
URI: | http://ntur.lib.ntu.edu.tw//handle/246246/10746 | 其他識別: | 912313B002317 | Rights: | 國立臺灣大學生物環境系統工程學系暨研究所 |
顯示於: | 生物環境系統工程學系 |
檔案 | 描述 | 大小 | 格式 | |
---|---|---|---|---|
912313B002317.pdf | 109.84 kB | Adobe PDF | 檢視/開啟 |
在 IR 系統中的文件,除了特別指名其著作權條款之外,均受到著作權保護,並且保留所有的權利。