太陽能熱水系統通常安裝在住宅屋頂以達到其最佳熱效率，但是台灣位於西太平洋颱風帶，熱水器可能因強大風力而損害，將大大降低系統所能提供之節能效益，因此針對系統設計而言，除了熱效率外，系統結構安全必須加以考量。本研究主要是利用風洞測試，探討紊流強度及風向角對家用及大型太陽能熱水系統氣動力特性的影響。在紊流強度方面，依颱風的風場特性，在風洞入口處安裝均勻格網提高流場紊流強度，風向角則介於0o-135o之間，此外阻塞比對於實驗結果的影響亦一併考量。本研究亦採用擋板之設計，在不同測試條件下，分析擋板之效應。
由壓力分佈結果可發現，隨著紊流強度增加，迴流區和側面渦流往板面上游處移動，壓力擾動量隨紊流強度增加而提高，板面風力負載隨流場紊流強度上升而增加。在傾斜平板前端安裝擋板後，整體上升力隨著擋板與傾斜平板投影面積比增加而下降。在風向角效應方面，傾斜平板上平均、擾動和峰值壓力隨風向改變而產生變化，當風向角增加時，左右對稱角渦流區域逐漸往單側集中，另一側逐漸消失，此時靠近傾斜平板上游處邊角處之渦流強度為最強。安裝水平圓柱或擋板後明顯改變上板面流場，尤其是迴流區與角渦流強度明顯減弱，進一步發現傾斜平板整體上升力明顯降低。此外進行風洞測試時，為確保數據正確性，模型阻塞比應小於5%以減低加速效應，本研究利用二座不同測試段尺寸之風洞與兩種尺寸之模型，以低阻塞比為集傾斜平板風壓數據為基準，當阻塞比增加時，在上板面前端迴流與側邊角渦流處區域風壓明顯受到加速效應，本研究亦利用Maskell阻塞比修正公式修正板面壓力誤差，在迴流區與角渦流區有不錯修正效果，但在氣流直接衝擊區修正效果較不明顯。

Solar water heaters (SWHs) are typically installed on the roofs of buildings in order to collect more solar energy. However, since Taiwan is located in the Southeast Pacific Ocean, the SWHs could be damaged by the strong wind force which is accompanied with typhoon. Thus, the safety of SWHs under severe wind loads during typhoon season is a critical issue in the system design of SWHs. In this study, the effects of crosswind and turbulence intensity (TI) on the aerodynamic characteristics of the residential (an inclined flat plate with a horizontal cylinder) and large-scale SWHs (an inclined flat plate only) are experimentally investigated. A turbulence generation grid installed at the inlet of the test section produces a highly turbulent flow. The incident wind directions of the test model range from 0o to 135o. The effects of the blockage ratio on the test results in the wind tunnel are also investigated. In addition, the integration with a guide plate with test model is also employed in the study. Effects of the various guide plate conditions on the models on the performances of SWHs are studied.
Increased turbulence intensity leads to a situation of the separation bubble and side-edge vortices moving upstream of the solar plate. It is observed that more intense fluctuating pressures and higher bending moment with TI on the models. With installing a guide plate, the uplift force is reduced with the increased projected area ratio of guide plate. With increased angle of wind incidence ("β)" , the original symmetrical distribution of corner vortices at "β =0 " moves to the windward side, while disappears in the other side. Also, the strengths of corner vortices become stronger near the windward corner. The areas of separation and corner vortices are shrunk after installing a guide plate or a cylinder on the model, which, in turn, causes reduction in uplift force.
It is found that the blockage ratio of model must be smaller than 5% to reduce flow acceleration over the test model in the wind tunnel test to ensure the accuracy of the experimental results. The mean surface pressures of the two-scale models are compared in the two different scales of wind tunnel. The significant flow acceleration is observed over the model with large blockage ratio, in particular, in the regions of separation and corner vortices. Maskell's method is found to be effective in correcting pressure data in the flow separation regions, but not for the stagnation region.

Awbi, H.B., 1978. Wind-tunnel-wall constraint on two-dimensional rectangular- section prisms. Journal of Wind Engineering and Industrial Aerodynamics, 3 (4), 285-306.
Barnard, R.H., 1981. Wind loads on cantilevered roof structures. Journal of Wind Engineering and Industrial Aerodynamics 8, 21-30.
Barnard, R.H., 2000. Predicting dynamic wind loading on cantilevered canopy roof structures. Journal of Wind Engineering and Industrial Aerodynamics 85, 45-57.
Bearman, P.W. Morel, T., 1983. Effect of freestream turbulence on the flow around bluff bodies. Progress in aerospace sciences. Journal of Wind Engineering and Industrial Aerodynamics 20 (2-3), 97-123.
Cao, S., Tamura, Y. Kikuchi, N., Saito, M. Nakayama, I., Matsuzaki, Y., 2009. Wind characteristics of a strong typhoon. Journal of Wind Engineering and Industrial Aerodynamics 97, 11-21.
Chang, K.C., Lee, T.S., Chung, K.M., 2006, Solar water heaters in Taiwan. Energy Policy 31,1299-1308.
Chang, K.C., Lee, T.S., Lin, W.M, Chung, K.M., 2008, Outlook for solar water heaters in Taiwan. Energy Policy 36,66-72.
Chang, K.C., Lin, W.M., Lee, T.S., Chung, K.M., 2009, Local market of solar water heaters in Taiwan: Review and perspectives. Renewable and Sustainable Energy Reviews 13,2605-2612.
Chen, F., Lu, S.M., Wang, E., Chang, Y.L., 2007, Renewable energy in Taiwan : its developing status and strategy. Energy 32,1634-1646.
Chen, F., Lu, S.M., Wang, E., Tseng, K.T., 2010, Renewable energy in Taiwan Renewable and Sustainable Energy Reviews, 14 (7), pp. 2029-2038
Chung, K.M., Chang, K.C., Chou, C.C., 2011. Wind load on residential and large-scale solar collector models. Journal of wind engineering and industrial aerodynamics, 99 (1), 59-64.
Chung, K.M., Chang, K.C., Liu, Y.M., 2008. Reduction of wind uplift of a solar collector model. Journal of wind engineering and industrial aerodynamics, 96 (8-9), 1294-1306.
Gad-el-Hak, M., 2000. Flow Control (Cambridge University Press)
Gu, F., Wang, J.S., Qiao, X.Q., Huang, Z., 2012. Pressure distribution, fluctuating forces and vortex shedding behavior of circular cylinder with rotatable splitter plates. Journal of fluids and structures, 28, 263-278.
Hiller, R., Cherry, N.J., 1981. The effects of stream turbulence on separation bubbles. Journal of Wind Engineering and Industrial Aerodynamics 8, 49-58.
Holmes, J.D., 2001. Wind loading of parallel free-standing walls on bridges, cliffs, embankments and ridges. Journal of Wind Engineering and Industrial Aerodynamics 89, 1397-1407.
Holmes, J.D., 2007. Wind loading of structures. 2nd edition, Taylor & Francis, London and New York, 78-83.
Hsu, U.K., Chang, K.C., Tyan. R.H., Wang, W.C., Liu, Y.C., 2011. Numerical studies of the uplift effect over a solar water heater in strong wind. Journal of Air Force Institute of Technology 1, 167-172
Hunt, A., 1982. Wind tunnel measurements of surface pressures on cubic building models at several scales. Journal of Wind Engineering and Industrial Aerodynamics, 10 (2), 137-163.
Kang S.H., Ahn, S.K. and Kwon, O.J., 2005, New blockage-correction method for separated flows in a subsonic wind tunnel. Journal of Aircraft, 42 (5), 1352-1354.
Kawai, H., Nishimura, G., 1996. Characteristics of fluctuating suction and conical vortices on a flat roof in oblique flow. Journal of Wind Engineering and Industrial Aerodynamics 60, 211-225.
Kawai, H., 1997. Structure of conical vortices related with suction fluctuation on a flat roof in oblique smooth and turbulent flows. Journal of Wind Engineering and Industrial Aerodynamics 71, 579-588.
Kawai, H., Yoshie, R., Wei, R., Shimura, M., 1999. Wind-induced response of a large cantilevered roof. Journal of Wind Engineering and Industrial Aerodynamics 83, 263-275.
Killen, G.P., Letchford C.W., 2001. A parametric study of wind loads on grandstand roofs. Engineering structure 23,725-735.
Kong, L. and Parkinson, G.V., 1997. A 3-D tolerant wind tunnel for general wind engineering tests. Journal of Wind Engineering and Industrial Aerodynamics, 69-71, 975-985.
Kopp, G.A., Surry, D., Chen, K., 2002. Wind loads on a solar array. Wind and structures, an international journal, 5 (5), 393-406.
Lam, K.M., To, A.P., 1995. Generation of wind loads on a horizontal grandstand roof of large aspect ratio. Journal of Wind Engineering and Industrial Aerodynamics 54/55, 345-357.
Lam, K.M., Zhao, J.G., 2002. Occurrence of peak lifting actions on a large horizontal cantilevered roof. Journal of Wind Engineering and Industrial Aerodynamics 90, 897-940.
Laneville, A. and Trepanier. J.Y., 1986. Blockage effects in smooth and turbulent flows: The case of two-dimensional rectangular cylinders. Journal of Wind Engineering and Industrial Aerodynamics, 22 (2-3), 169-176.
Letchford, C.W., Killen, G.P., 2002. Equivalent static wind loads for cantilevered grandstand roofs. Engineering structure 24,207-217.
Maskell, E. C., 1963. A Theory of the blockage effects on bluff bodies and stalled wings in a closed wind tunnel. A.R.C.R. & M. 3400.
Mecker, E., 1986, A blockage correction for automotive testing in a wind tunnel with closed test section. Journal of Wind Engineering and Industrial Aerodynamics, 22 (2-3), 149-167.
Moradian, N., Ting, D.S.K., Cheng, S., 2009, The effects of freestream turbulence on the drag coefficient of a sphere. Experimental thermal and fluid science. 33 (3), 460-471.
Naeeni, N., Yaghoubi, M., 2007. Analysis of wind flow around a parabolic collector (1), Renewable Energy, 32 , 1898-1916
Nakamura, Y., Ohya, Y., 1984. The effects of turbulence on the mean flow past two-dimensional rectangular cylinders. Journal of Fluid Mechanics, 149, 255-273
Oaulotto, C., Ciampoli, M., Augusti, G., 2006, Wind tunnel evaluation of mean wind pressure on a frame-type signboard. Journal of Wind Engineering and Industrial Aerodynamics 94, 397-413.
Ota, T., Kamoto, Y. and Yoshikawa, H., 1994. A correction formula for wall effects on unsteady forces of two-dimensional bluff bodies. Journal of Fluids Engineering, 116 (3), 414-418.
Radu, A., Axinte, E., 1989. Wind forces on structures supporting solar collectors. Journal of wind engineering and industrial aerodynamics, 32 (1-2), 93-100.
Repetto1, M.P., Solari, G., 2004. Directional Wind-Induced Fatigue of Slender Vertical Structures. Journal of structural engineering, 130 (7), 1032-1040.
Saathoff, P.J. Melbourne, W.H., 1987. Freestream turbulence and wind tunnel blockage effects on streamwise surface pressures. Journal of Wind Engineering and Industrial Aerodynamics, 26 (3), 353-370.
Strazzo, S., 2011. Low-frequency minimum temperature variability throughout the e southeastern united states during the 1970s: regime shift or phase coincidence? The Florida state university college of arts and arts and sciences.
Takeda, K., Kato, M., 1992. Wind tunnel blockage effects on drag coefficient and wind-induced vibration. Journal of Wind Engineering and Industrial Aerodynamics, 42 (1-3), 897-908.
Tsai, W., Chou, Y., 2005. Overview of environmental impacts, prospects and policies for renewable energy in Taiwan. Renewable and Sustainable Energy Reviews 9, 119-147.
Uematsu, Y., Ymada, M., Sasaki, A., 1996. Wind-induced dynamic response and resultant load estimation for a flat long-span roof. Journal of Wind Engineering and Industrial Aerodynamics 65, 155-166.
Wood, G.S., Denoon, R.O., and Kwok, K.C.S., 2001. Wind loads on industrial solar panel arrays and supporting roof structure. Wind and structures, an international journal, 4 (6), 481-494.
Wu, J., Huang,Y., 2006. Renewable energy perspectives and support mechanisms in Taiwan. Renewable Energy 31,1718-1732.
Utsunomiya, H., Nago, F., Ueno, Y., Noda, M., 1993. Basic study of blockage effects on bluff bodies, Journal of Wind Engineering and Industrial Aerodynamics, 49 (1-3), 247-256.
Zhao, J.G., Lam, K.M., 2002. Characteristics of wind pressures on large cantilevered roofs: effect of roof inclination. Journal of Wind Engineering and Industrial Aerodynamics 90, 1867-1880.