| 研究生: |
陳奕潤 Chen, Yi-Jun |
|---|---|
| 論文名稱: |
風洞阻塞比及自由流紊流強度對太陽能板風力負載之影響 Wind Loading on the Solar Panel: Blockage and Free Stream Turbulence Effect |
| 指導教授: |
張克勤
Chang, Keh-Chin 鍾光民 Chung, Kung-Ming |
| 學位類別: |
碩士 Master |
| 系所名稱: |
工學院 - 航空太空工程學系 Department of Aeronautics & Astronautics |
| 論文出版年: | 2011 |
| 畢業學年度: | 99 |
| 語文別: | 中文 |
| 論文頁數: | 169 |
| 中文關鍵詞: | 太陽能熱水系統 、升力 、阻力 、阻塞比 、紊流強度 、三維效應 |
| 外文關鍵詞: | Solar water heater system, Lift force, Drag force, Blockage ratio, Turbulence intensity,, Three-dimensional effect |
| 相關次數: | 點閱:134 下載:6 |
| 分享至: |
| 查詢本校圖書館目錄 查詢臺灣博碩士論文知識加值系統 勘誤回報 |
在石化能源減少造成國際油價高漲的現況下,再生能源的使用,已成為政府節能減碳的重要議題。台灣由於地處亞熱帶與熱帶之北緯22°~25°之間,日照時間長、日光偏斜角度小,非常適合發展太陽能利用。但因為台灣位於太平洋的颱風移動路徑上,為全世界受颱風侵襲的三個主要區域之一,平均每年會遭受到3.7個颱風侵襲。如何減少因強風吹襲造成太陽能集熱板的損壞是一個重要的課題。
在前人的研究中,已經針對了不同風速、集熱板不同的安裝攻角、前方有無安裝水桶,以及為減少升力加裝不同安裝角和大小的擋板時的集熱板壓力分佈,與空氣動力進行了實驗與分析。但前人所做的研究是在較高的阻塞比(8.72 % ~ 25.26 %)下進行,所以得到之數據可能會因阻塞比的影響而產生誤差。同時,前人所做之研究都是在來流紊流強度< 1 %的情況下進行實驗。但在真實颱風流場的量測中可以發現,颱風流場的紊流強度大小約是在10 % ~ 20 %的範圍內。而一些研究紊流效應的文獻指出,紊流強度的增加會改變平均與擾動壓力的分佈與大小。所以本研究主要是針對這兩種效應對集熱板壓力分佈,與空氣動力的影響進行討論。
從實驗的結果可以發現阻塞比跟自由流紊流強度,都會對量測到之壓力分佈與受力產生影響。當阻塞比較大時,因為模型附近的氣流受到限制而加速,所以壓力分佈會較不平順,集熱板的受力較大。這樣的情況可以利用文獻上提到的相關公式,對壓力分佈進行修正,並得出修正因子對阻塞比之關係。但因為測試模型的形狀和文獻中提到的不同,所以得到如下和文獻中敘述不同的關係式。
大型系統:
1 - A2^2 = 1.8465[(S / C)total + A*(S / C)plate] - 0.0336
(S / C)total = 3.87 % ~ 7.48%
家用系統:
1 - A2^2 = 2.6288[(S / C)total + A*(S / C)plate] - 0.1582
(S / C)total = 7.62 % ~ 11.23 %
而紊流強度高時,平均與擾動壓力都會出現如文獻中提到的變化,升阻力的大小也會增加。但是當集熱板攻角增加時,紊流效應的影響逐漸減少,對升力係數的影響從攻角15°時的1.43倍到30°變成1.12倍。
由於本研究有對整個集熱器平面進行壓力量測,所以可以進行平面的壓力積分而得到三維之升阻力係數。在攻角15°~30°時,因為三維之升阻力係數增加了側邊渦流造成之低壓區的影響,所以較二維的升阻力係數高7 % ~ 34 %。
The rising of international oil prices caused by the lack of fossil fuels in current circumstances, the using of renewable energy has become an important issue for government. Taiwan is located in the subtropical and tropical, between latitude 22 ° ~ 25 °.It’s very suitable for the development of solar energy, because the long hours of sunshine and the small angle of daylight deflection. But Taiwan is located on the path of typhoon of the west Pacific, one of the three main areas typhoons strike in the world. There are 3.7 typhoons strike Taiwan each year. Reducing the damage to solar panels caused by strong winds is an important issue.
In previous studies the pressure distribution and aerodynamics on the solar collector in different wind speed, different of installation angle of attack, whether the installation of the tank or not, and the installation of various size and installation angle of baffle for reducing lift force to the solar collector, has been carried out by experiments and analysis. However, previous studies are done at high blockage ratio condition(8.72 % ~ 25.26 %), the data may be due to the effects of blocking produce errors than. At the same time, the previous studies are done in the condition of turbulence intensity < 1%. But in the measurement of real flow field during typhoon strikes Taiwan. The turbulence intensity of air flow is in the scale of 10% to 20%. Some research literature indicates increasing in turbulence intensity will change the distribution and magnitude of average and perturbation pressure. Therefore, this study is discussing about these two effects on the collector plate pressure distribution and the aerodynamics.
From the results of experiments, it can be found blockage ratio the free stream turbulence intensity, would affect the measurement of the pressure distribution and the aerodynamics of the collector. The higher blockage ratio causes the acceleration of the flow near the model not only makes the pressure distribution will be less smooth than the cases of lower blockage ratio but also produces larger lift and drag force on the collector. This effect can be corrected by using the formula which mentioned in the literature. And the relationship between correction factor and the blockage ratio can be derived. Because the shape of the test model and the models mentioned in the literature are different, so the relationship has been described below is different within the literature.
For commercial system:
1 - A2^2 = 1.8465[(S / C)total + A*(S / C)plate] - 0.0336
(S / C)total = 3.87 % ~ 7.48%
For residential system:
1 - A2^2 = 2.6288[(S / C)total + A*(S / C)plate] - 0.1582
(S / C)total = 7.62 % ~ 11.23 %
The distribution and magnitude of average and perturbation pressure changes as mentioned in the literature and the magnitude of lift and drag will increase in the condition of high turbulence intensity. But the effect of turbulence deceases when the angle of attack of the collector increases. The effect on the lift coefficient is from 1.43 times at 15° to 1.12 times at 30°.
As the study include the measurements of the entire collector surface pressure. The three-dimensional lift and drag coefficient on the collector can be obtained by the integral of surface pressure. The three-dimensional lift and drag coefficient include the effect of corner vortex, which causes the increasing the area of low pressure. And it makes the three-dimensional lift is 7% to 34% more than two-dimensional lift coefficient, while α = 15°~ 30°.
[1] http://www.cmegroup.com/
[2] 經濟部能源局,"2010年能源產業技術白皮書",p.240 (2010.4)
[3] 中央氣象局網站 ( http://www.cwb.gov.tw/ )
[4] 連雅鳳、張克勤、李聰盛、鍾光民,”國內太陽能熱水器推廣及使用情形頗析”,太陽能及新能源學刊,第11卷, 第一、二期, p.9 ~ p.11 (2006.12)
[5] 呂錫民,"我國裝置太陽能潛力探討,能源報導,pp.31-33 (2010.11)
[6] 經濟部能源局,"國內能源翦影",能源報導,p.37 (2010.11)
[7] 李清安、張克勤、李聰盛、鍾光民,”颱風對國內安裝使用太陽能熱水系統之損害探討”,工程,第80卷, 第四期, pp.134-142 (2006.12)
[8] 陳正改,"氣象災害",中央氣象局
[9] 謝信良、王時鼎、鄭明典、葉天降,"百年(1897~1996)侵襲台灣颱風之統計分析",中央氣象局
[10] 內政部,"風災災害防救業務計畫"(2010.4)
[11] 蕭葆羲, 風工程, 科技圖書, 台灣, (2005)
[12] 陳俊谷,"降低太陽能熱水器之風損研究", 國立成功大學航空太空研究所碩士論文 (2006)
[13] K. Chung, K. Chang, Y. Liu, "Reduction of wind uplift of a solar collector model", Journal of Wind Engineering and Industrial Aerodynamics, Volume 96, Issues 8-9, pp.1294 -1306 (2008)
[14] 修治平,"導流板對不同角度集熱板之空氣動力特性研究", 國立成功大學航空太空研究所碩士論文 (2007)
[15] 周晉成,"儲水桶對太陽能板空氣動力效應分析", 國立成功大學航空太空研究所碩士論文 (2009)
[16] 王偉政,"太陽能熱水器之升力與阻力數值模擬分析研究", 國立成功大學航空太空研究所碩士論文 (2010)
[17] Bao Shi Shiau, "Velocity spectra and turbulence statistics at the northeastern coast of Taiwan under high-wind conditions ", Journal of Wind Engineering and Industrial Aerodynamics, Volume 88, Issues 2-3, pp.139- 151 (2000)
[18] Bao Shi Shiau, Yuan Bin Chen, "In situ measurement of strong wind velocity spectra and wind characteristics at Keelung coastal area of Taiwan", Atmospheric Research, Volume 57, Issue 3, pp.171-185 (2001)
[19] Y.L. Xu, S. Zhan, "Field measurements of Di Wang Tower during Typhoon York", Journal of Wind Engineering and Industrial Aerodynamics, Volume 89, pp.73-93 (2001)
[20] Binglan Wang, Fei Hu, Xueling Cheng, "Wind Gust and Turbulence Statistics of Typhoons in South China", Acta Meteorologica Sinica, Volume 25, Number 1, pp.113-p.127 (2010)
[21] P. H. A. Barbosa, M. Cataldi, A. P. S. Freire, "Wind tunnel simulation of atmospheric boundary layer flows", Journal of the Brazilian Society of Mechanical Sciences, Volume 24, no.3 (2002)
[22] P. E. Roach, "The generation of nearly isotropic turbulence by means of grids", Heat and Fluid Flow, Volume 8, Number 2, pp.82-92 (1987)
[23] P. J. Saathoff, W. H. Melbourne, "The Generation of Peak Pressures in Separated/Reattaching Flows", Journal of Wind Engineering and Industrial Aerodynamics, Volume 32, pp.121-134 (1989)
[24] Q. S. Li, W. H. Melbourne, "An experimental investigation of the effects of free-stream turbulence on streamwise surface pressures in separated and reattaching flows", Journal of Wind Engineering and Industrial Aerodynamic, Volume 54/55, pp.313-323 (1995)
[25] P. W. Bearman, "An investigation of the forces on flat plates normal to a turbulent flow", Journal of Fluid Mechanics , Volume 64, part 1, pp.177-198 (1971)
[26] P. J. Saathoff, W. H. Melbourne, "Effects of free-stream turbulence on surface pressure fluctuations in a separation bubble", Journal of Fluid Mechanics , Volume 337, pp.1-24 (1997)
[27] A. Thom, "Blockage Correction in a High Speed Wind Tunnel", R&M 2033 (1943)
[28] John G. Herriot, "Blockage corrections for three-dimensional-flow closed-throat wind tunnels, with consideration of the effect of compressibility", TR 995 (1950)
[29] E. C. Maskell, "A Theory of the Blockage Effects on Bluff Bodies and Stalled Wing in a Closed Wind Tunnel", ARC R&M 3400 (1965)
[30] William H.Rae, Jr., Alan Pope, "Low-Speed Wind Tunnel Testing", John Wiley & Sons, Inc., USA (1984)
[31] Louis G. Stafford, "A Streamline Wind-Tunnel Working Section for Testing at High Blockage Ratios", Journal of Wind Engineering and Industrial Aerodynamic, Volume 9, pp.23-31 (1981)
[32] D.M. Sykes, "Advances in Road Vehicle Aerodynamics", Fluid Engineering, pp. 311-321 (1973)
[33] J. T. Templin and S. Raimondo, "Experimental Evaluation of Test Section Boundary Interference Effects in Road Vehicle Tests in Wind Tunnels", Journal of Wind Engineering and Industrial Aerodynamic, Volume 22, pp.129-148 (1986)
[34] G.W. Carr, "Wind tunnel blockage corrections for road vehicles", Mot. Ind. Res. Assoc.,Rep. MIRA 1971/4.
[35] 鍾光民, "成大航太中心LWT 46低速風洞校驗", 國立成功大學航太科技研究中心報告 (1996)
[36] Hunt, "Wind-Tunnel Measurements of Surface Pressures on Cubic Building Models at Several Scales", Journal of Wind Engineering and Industrial Aerodynamic, Volume 10, pp.137-163 (1982)
[37] 高義明, "內政部建研所環境風洞校驗及二維鈍形體空氣動力流場實驗研究", 國立成功大學航空太空研究所碩士論文 (2005)
[38] 黃信文, "紊流場與均勻流場對垂直軸風機影響之研究 ", 國立成功大學航空太空研究所碩士論文 (2010)
[39] Scanivalve Corp., "RAD3200 System instruction and service manual", Scanivalve Corp. (2007)
[40] Scanivalve Corp., "ZOC 33/64Px and ZOC 33/64PxX Electronic Pressure Scanning Module instruction and service manual", Scanivalve Corp. (2003)
[41] Finn E. Jørgensen, "HOW TO MEASURE TURBULENCE WITH HOT-WIRE ANEMOMETERS", Dantec Dynamics A/S (2004)
[42] A. Laneville, J. Y. Trepanier, "Blockage Effect in Smooth and Turbulent Flows: The Case of Two-Dimesional Rectangular Cylinders", Journal of Wind Engineering and Industrial Aerodynamics, Volume 22, pp.169-176 (1986)
[43] http://www.dantecdynamics.com/