基于示踪气体法的捕风器通风特性实验研究
首发时间:2019-04-30
摘要:在全球变暖和能源结构紧张的大背景下,自然通风在当代建筑中的应用越来越为人所重视,一些实用且具体的被动式自然通风技术应运而生。捕风器作为一种典型的被动式自然通风设备,在自然条件下室内通风不足时,将风力引入到室内,实现强化通风。本研究采用实验测试与数值模拟分析结合的方法,对三种不同截面的捕风器在室外风场影响下的通风性能进行全面的探索和分析。实验在梯度增加的四个室外风速(3m/s~7m/s)条件和五个风向(0 ~90 )条件下进行,捕风器连接到一个尺寸为3.5mⅹ4mⅹ3m的房间构成整个通风系统,根据截面、风速、风向的变化一共60个实验工况。实验得到室内换气次数与室外风速呈正相关变化,且不同角度间的差异只有在较高风速条件(大于4m/s)下时才体现出显著性;风向与横截面对通风性能有耦合影响,其中0 和90 总是出现最佳的结果;此外相比于圆形,矩形和方形截面具有更高的通风效率。
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An Experimental Study on Windcatchers by Gas Tracing Method
Abstract:Under the general background of global warming and energy shortage, the passive application of natural ventilation in contemporary architecture have become more and more valued by people. Some practical and specific passive technologies of natural ventilation emerge and are favored by many architects and engineers. As a kind of typical passive equipment of natural ventilation, windcatchers capture the wind outside and sink it down into the interior under insufficient ventilation conditions for strengthening air movement. In this paper, An experimental investigation and CFD simulations have been carried out to evaluate the performance of three (i.e. circular, rectangle and square) four-sided wind-catchers with different section types but equivalent inlet diameter. It has been performed under four incremental wind speeds (1-7m/s) and five angles (0 -90 ). Practical and functioning wind-catcher systems operated in real conditions was connected to the top of a roof to a room with dimensions 3.5m by 4m by 3 m (height, width and length) respectively. 60 working condition scenarios were designed in total in terms of cross section, wind velocities and incident angles in the city of Chongqing. Tracer gas methods using CO2 concentration was employed to calculate the air change rate of the room considering the air exchange from the wind-catcher. The results show that the section type, wind speed and incident angles are main contributing factors in the performance of the wind-catcher systems. Notably, comparing with round section, the rectangle and square systems provide higher efficiencies. The ventilation rate increase with wind speeds, while differences among various angles are only distinctive when outdoor velocity is above 4m/s in this paper, indicating that the importance as influence factor of incident angle for ventilation performance depends on outdoor wind sources to a great extent. In addition, direction and cross section had a coupling influence on the ventilation performance, from which angles 0 and 90 always provided significant results.
Keywords: Natural ventilation, Wind-catcher, Indoor-outdoor environment, Gas-tracing method
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基于示踪气体法的捕风器通风特性实验研究
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