Experimental study of turbulent wind flow over arc roofs: an ancient simple way to low energy buildings
محورهای موضوعی : فصلنامه شبیه سازی و تحلیل تکنولوژی های نوین در مهندسی مکانیک
Farhad Raeiszadeh
1
(Energy Research Center, Shahrekord Branch, Islamic Azad University, Shahrekord, Iran)
Mehdi Jahangiri
2
(Energy Research Center, Shahrekord Branch, Islamic Azad University, Shahrekord, Iran.)
کلید واژه: Reverse flow, Recirculation, Arc roof, Hot wire, Separation.,
چکیده مقاله :
In hot, dry areas around the world, buildings are planned to shield against strong winds and to offer natural cooling during the summer. Many of these structures have curved or domed roofs, like arcs, vaults, or semi-circles. This paper presents an experimental study of air flow over arc roofs mounted over a flat surface with various diameters (80, 120, and 200 mm) at different flow velocities (5, 10, and 15 m/s). For this aim, models of half circle shape with the same length and different diameters have been made and installed in a subsonic wind tunnel. Using a vertical hot wire probe, measurements were conducted to analyze flow characteristics, which included mean flow velocity directions, root mean square values representing turbulent fluctuations, and the skin friction coefficient. These measurements helped in establishing the fluid pattern over the vault. Also, it was found that with increasing Reynolds number, fluid characteristics such as separation angle, recirculation length are increasing and location of maximum velocity remains almost constant. Results of experimental measurements are compared with flat roofs data and better thermal performance of arc roofs is observed.
In hot, dry areas around the world, buildings are planned to shield against strong winds and to offer natural cooling during the summer. Many of these structures have curved or domed roofs, like arcs, vaults, or semi-circles. This paper presents an experimental study of air flow over arc roofs mounted over a flat surface with various diameters (80, 120, and 200 mm) at different flow velocities (5, 10, and 15 m/s). For this aim, models of half circle shape with the same length and different diameters have been made and installed in a subsonic wind tunnel. Using a vertical hot wire probe, measurements were conducted to analyze flow characteristics, which included mean flow velocity directions, root mean square values representing turbulent fluctuations, and the skin friction coefficient. These measurements helped in establishing the fluid pattern over the vault. Also, it was found that with increasing Reynolds number, fluid characteristics such as separation angle, recirculation length are increasing and location of maximum velocity remains almost constant. Results of experimental measurements are compared with flat roofs data and better thermal performance of arc roofs is observed.
[1] Shaeri, J., Habibi, A., Yaghoubi, M., & Chokhachian, A. (2019). The optimum window-to-wall ratio in office buildings for hot‒humid, hot‒dry, and cold climates in Iran. Environments, 6(4), 45.
[2] Yaghoubi, M. A. (1991). Air flow patterns around domed roof buildings. Renewable Energy, 1(3-4), 345-350.
[3] Bahadori, M. N. (1978). Passive cooling systems in Iranian architecture. Scientific American, 238(2), 144-155.
[4] Yaghoubi, M., & Velayati, E. (2004). Analysis of wind flow around various domed-type roofs. IMEC, Kuwait, 209-217.
[5] Abohela, I., Hamza, N., & Dudek, S. (2013). Effect of roof shape, wind direction, building height and urban configuration on the energy yield and positioning of roof mounted wind turbines. Renewable Energy, 50, 1106-1118.
[6] Ozmen, Y., Baydar, E. R. T. A. N., & Van Beeck, J. P. A. J. (2016). Wind flow over the low-rise building models with gabled roofs having different pitch angles. Building and Environment, 95, 63-74.
[7] Shan, W., Yang, Q., Guo, K., & Tamura, Y. (2023). Effects of slope curvature, ridge height and layered roofs on wind pressures on traditional-Chinese-style gable-hip and gable roofs. Journal of Building Engineering, 70, 106300.
[8] Yaghoubi, M., Kenary, A. and Mortazavi, M. Numerical Analysis of Wind Flow around Semi-circular Roof Buildings, Proceeding of 10th ISME, Khaje Nasir University, 2002.
[9] Yaghoubi, M., & Mahmoodi, S. (2004). Experimental study of turbulent separated and reattached flow over a finite blunt plate. Experimental Thermal and Fluid Science, 29(1), 105-112.
[10] Kays, W. M., Crawford, M. E., & Weigand, B. (1980). Convective heat and mass transfer (Vol. 4). New York: McGraw-Hill.
[11] Shames, I. (2003). Mechanics of Fluids (4thedn) McGraw-Hill.
[12] Hadavand, M., Yaghoubi, M., & Emdad, H. (2008). Thermal analysis of vaulted roofs. Energy and Buildings, 40(3), 265-275.
[13] Tang, R., Meir, I. A., & Wu, T. (2006). Thermal performance of non-air-conditioned buildings with vaulted roofs in comparison with flat roofs. Building and Environment, 41(3), 268-276.
[14] Akbarpoor, A. M., Gilvaei, Z. M., Poshtiri, A. H., & Zhong, L. (2022). A hybrid domed roof and evaporative cooling system: thermal comfort and building energy evaluation. Sustainable Cities and Society, 80, 103756.
[15] Pagnini, L., Delfino, F., Piccardo, G., & Repetto, M. P. (2023). Sustainability to wind actions of a new roofing structure in a green university campus. Building and Environment, 245, 110864.
[16] Dai, S. F., Liu, H. J., Chu, Y. J., Lam, H. F., & Peng, H. Y. (2022). Impact of corner modification on wind characteristics and wind energy potential over flat roofs of tall buildings. Energy, 241, 122920.
[17] Yu, Z., Zhu, F., Cao, R., Chen, X., Zhao, L., & Zhao, S. (2019). Wind tunnel tests and CFD simulations for snow redistribution on 3D stepped flat roofs. Wind and Structures, 28(1), 31-47.
[18] Castelli, M. R., Castelli, A., & Benini, E. (2012). Numerical Simulation of the Turbulent Flow over a three-Dimensional Flat Roof. Engineeringand Technology, 69, 980-986.
[19] Zhou, X., Kang, L., Gu, M., Qiu, L., & Hu, J. (2016). Numerical simulation and wind tunnel test for redistribution of snow on a flat roof. Journal of Wind Engineering and Industrial Aerodynamics, 153, 92-105.
[20] Ferreira, A. D., Thiis, T., Freire, N. A., & Ferreira, A. M. (2019). A wind tunnel and numerical study on the surface friction distribution on a flat roof with solar panels. Environmental Fluid Mechanics, 19, 601-617.
