Investigation of Street Canyon Phenomena in Large-Scale Turbulence

利用大气风洞对加热街道沿线建筑物周围风结构和街道冷却现象进行了风洞实验。实验参数为街道宽度、建筑物的高度和排列、横流的湍流强度。采用烟雾线法进行流动可视化，采用热像仪对街道表面进行热测量。(1)影响街道降温的主要气流为(a)上游建筑屋顶的分离流，(b)相邻建筑之间的流动，(c)上游建筑后或下游建筑前的环流，(d)上游建筑后湍流运动的尾流。(2)通过湍流运动，大尺度湍流中街道温度分布比网格湍流更均匀。(3)当下游建筑高于上游建筑时，下游建筑前方的路面被下游建筑前方稳定的循环流显著冷却。(4)街道温度在狭窄街道上比在宽阔街道上更为均匀。这个数据库是为城市规划而建立的。

Wind tunnel experiments of wind structure around buildings located along a heated street and cooling phenomena of the street were conducted by using atmospheric wind tunnels. The experimental parameters were a street width, the height and the arrangement of the buildings, the turbulent intensity of a cross flow. The smoke wire method for flow visualizations and a thermal camera for the thermal measurements of the street surface were employed.(1) Main flows which affect on the cooling of the street were (a) separated flows from the roof of upstream -side buildings, (b) flows between buildings located side by side, (c) circulation flows behind upstream-side buildings or in front of downstream-side buildings, (d) wake behind upstream-side buildings by turbulent motions.(2)By turbulent motions, the temperature distributions of the street were more uniform in the large-scale turbulence than in the grid turbulence.(3)In the case of downstream-side buildings which are taller than upstream-side buildings, the streetsurface around front of the downstream-side buildings was remarkably cooled by stable circular flows in front of down-side buildings.(4) Street temperature was more uniform on the narrow street than on the wide street.(5) The database was built up for urban planning.