捕风系统通风性能的数值模拟

捕风装置作为一种新兴的自然通风技术,在气候温和地区,比如英国的建筑中,得到了普遍应用.基于广泛使用的计算流体动力学(CFD)商用软件Fluent,对一种常见的方形截面捕风系统的通风性能进行了研究.建立了0.5 m/s、1 m/s、2 m/s、3 m/s、4 m/s、5 m/s、6 m/s风速和0°至45°范围内4个风向角条件下500 mm边长的方形捕风系统模型.CFD模型计算结果与实验结果在低风速下吻合良好,认为在高风速下有相对较大的误差是由于空气进口的均匀性变差引起的.通过模拟图像能够观察到捕风装置风道内部详细的气流运动,这样就很容易确定使用实验手段难以辨别的4个风道的送排风作用,从而可以利用数值模拟手段给出改进的计算结果.对捕风装置的性能与外界风速和风向的关系也做了讨论.与风道测试相比,CFD软件容易方便地得到结果,为设备的改进发展提供全面的设计参考.

Assessment of Performance of Wind Catcher System Using Numerical Method

Wind catchers are innovative technique for the application of nature ventilation in buildings in areas with temperate climates such as the United Kingdom.Based on the widely available computational fluid dyna-mics(CFD) commercial code Fluent,the present work attempts to provide an insight into the ventilation perfor-mance of a generic square-section wind catcher system.A 500-mm-square wind catcher system is modeled for nominal wind velocities of 0.5,1,2,3,4,5 and 6 m/s and four different directions taken in the range of 0 to 45 degrees.The results obtained using CFD models are correlated well with the experimental results at low wind velocities.The relatively large difference between the numerical and experimental results at high velocity can be due to the decreasing uniformity of air inlet.A full picture of the air movement inside the wind catcher quadrants is observed.It clearly indicates the supply or extract action of the four quadrants for the air which is difficult to be determined experimentally.So numerical method can be used to give improved computational results.The variation of the performance of wind catcher with wind velocity and wind direction is also discussed.Compared with wind tunnel tests,the CFD code is found to be more convenient.