风向随高度的偏转及其对指数廓线的影响——以广州主城区为例

在廓线指数的确定中,不同高度来流方向相同的假定很难得以保证。特别是超高层建筑密集的区域,热力与动力作用使风向随高度的变化复杂化。因此,风向的偏转产生的效应必须要给予重视。以高层建筑密集的广州主城区为例,基于激光雷达在4个不同测点获取1 km以下的垂直风塔数据,利用分钟尺度的高频样本,在划分随高度风向组合类型的基础上,分析了风向偏转对廓线指数的影响以及廓线指数α形成的机理。风向偏转的校正对指数廓线的发育在结构、均值以及高度分布上均产生影响,但最明显的优势是提高了廓线指数表达的科学性。测点所处的风场环境和来流经过的下垫面的建筑高度离散度决定了风廓线指数α。

The deflection of wind direction with height and its influence on exponential profiles: The example of the main urban area of Guangzhou

In determining the profile index α, it is difficult to confirm the assumption that all incoming flow at different heights has the same direction. Especially in areas where super high-rise buildings are dense, thermal energy and dynamic energy complicate the change of wind direction with height. Therefore, attention should be paid to the effect of deflection of wind direction. This research takes the main urban area of Guangzhou with dense high-rise buildings as an example, lidar was used to obtain vertical wind tower data below 1 km at 4 different observation points, high-frequency samples at minute scale were adopted, and typology of wind direction deflection with height was classified. All these serve to analyze the influence of wind deflection on profile index and the formation mechanism of α. The correction of wind direction deflection has an impact on the development of the index profile in terms of structure, mean value and height distribution, but the most obvious contribution is that it improves the scientific expression of the profile index. The finding of this research is that the wind profile index is determined by the wind field environment, at which the measuring point is located, and the dispersion of building heights of the underlying surface, through which the incoming flows pass.