摘要
基于realizable K-ε湍流模型,采用CFD模拟研究了背风建筑屋顶不同强度热效应产生的自然对流作用对建筑周围流场、温度场及屋顶烟囱排放污染物扩散的影响。研究中采用理查德森数Ri(0~1.15)表示背风建筑屋顶受太阳辐射产生的热浮升力与来流惯性力的相互作用强弱,并通过风洞试验对构建的数值模型进行了验证。结果表明:数值模型计算结果在湍流施密特数Sc_t=0.1时与风洞试验实测结果吻合最好;当Ri<0.78时,随Ri增大,迎风建筑A的背风区流动结构变化显著,街道峡谷背风面及行人呼吸高度面污染物浓度显著降低,降幅分别可达58%和70%;Ri≥0.78时,热浮升力占据主导,迎风建筑背风区流动结构及污染物的分布基本不再发生变化,而且由于热浮升力明显的抬升作用,使得街道峡谷内污染物浓度水平较低。
Studies the influence of natural convection caused by the different roof thermal effect of the leeward building on the surrounding flow field,temperature field and the diffusion of gaseous pollutants emitted from the rooftop stack using CFD models coupled with the realizable K-εturbulence model.Uses the Richardson number(Ri,from 0 to 1.15)to indicate the relative strength of the interaction between the thermal buoyancy force due to the heated building roof by solar radiation and the inertial force of the incoming flow.Verifies the numerical models by the wind tunnel experiments.The results show that there is a better agreement between the measured data by wind tunnel experiments and the predicted results by CFD models when the turbulent Schmidt number(Sc_t)is 0.1.When Ri is less than 0.78,with the increase of Ri,the flow structure at the leeward side of the Building A changes significantly.The pollutant concentrations near the leeward wall of street canyon and on the pedestrian level plane are significantly reduced by 58%and 70%,respectively.Meanwhile,when Ri is greater than or equal to 0.78,compared with the inertial force,the thermal buoyancy force dominates,and the flow structure and pollutant distribution at the leeward side of the Building A basically do not change.In addition,due to the obvious uplift effect of thermal buoyancy,the concentration level of pollutants in street canyons is relatively low.
作者
黄晓天
黄远东
许诺
崔鹏义
Huang Xiaotian;Huang Yuandong;Xu Nuo;Cui Pengyi(University of Shanghai for Science and Technology,Shanghai,China)
出处
《暖通空调》
2020年第3期95-102,共8页
Heating Ventilating & Air Conditioning
基金
国家自然科学基金重点资助项目(编号:51536006)
上海市青年扬帆计划项目(编号:18YF1417600)。
关键词
屋顶热效应
污染物扩散
风洞试验
烟囱排放
数值模拟
理查德森数Ri
roof thermal effect
pollutant diffusion
wind tunnel experiment
stack emission
numerical simulation
Richardson number(Ri)
