街谷垂直涡旋的分析和垂直速度计算

ANALYSIS OF VERTICAL VORTEX IN THE STREET AND COMPUTATION OF ITS VERTICAL VELOCITY

本文根据对广州市三类街道所作的气象观测得到的资料,分析了街谷内垂直涡旋的形态和出现条件,并用经验公式估算了街谷内的垂直速度。结果表明街谷高宽比和垂直于街道的屋顶风速是垂直涡旋形成的两个重要条件。高宽比和屋顶风速越大,街谷内越易形成垂直涡旋。当街道高宽比大于0.5,垂直于街道的屋顶风速大于0.7m/s时,街谷内常有垂直涡旋存在。街谷内平均垂直速度随屋顶风速增大而增大。屋顶风速为2m/s时,街谷内平均垂直速度为3.7cm/s,屋顶风速每增大2m/s。平均垂直速度约增加3cm/s。

Based on the data of meteorological observation in three types of streets in Guangzhou City, the shapes and formation conditions of vertical vortexes are analysed, and their vertical velocity are computed by using an empirical formula. It is found that the ratio of height and width of the street canyon and the cross-street component of roof wind velocity are the most important factors for the formation of the vertical vortex in the street canyon. The larger the ratio of height and width of street canyon and the cross-street component of roof velocity are, the easier the vertical vortex in the street canyon will form. When the ratio of height and width of a street canyon is larger than 0.5 and the cross-street component of roof wind velocity is larger than 0.7m/s, there is often a vertical vortex in the street canyon, and its average vertical velocity increases as the roof wind velocity enlarges, When the cross-street component of roof wind velocity is 2m/s, the average vertical velocity of the vortex is 3.7cm/s, and the vertical velocity will increase about 3cm/s for every 2m/s increase of the cross-street component of roof wind velocity.