城市建筑环境中阵风特征的实验研究

Experimental Study of Gust Characteristics in the Urban Built Environment

针对缺乏城市建筑环境内风场阵风特征相关研究的问题,本文对内蒙古呼和浩特市某建筑群内风场特征开展了为期12个月的现场实验测量,获取了建筑顶面0.86m高度上6个测点上的阵风因子、阵风幅度及过剩能量含量随风速的变化规律,初步掌握了建筑环境内风场的阵风特征,结果表明:6个测点上的阵风因子都随着平均风速的增大而减小;除了距离建筑顶面高度较低的A1测点外,其他测点阵风因子大部分都大于1.4(IEC标准),IEC标准中的阵风模型将低估建筑顶面的阵风因子;6个测点在实验期间未出现或极少出现振幅大于9.8 m/s的极端阵风活动;6个测点的过剩能量含量均随着平均风速的增大而减小,同时在距离建筑顶面高度越大或适当远离建筑边缘的地方,过剩能量含量均会增大,将风力机安装在这些地方都有可能获得更多的过剩能量。以上所得结果可为适合于城市建筑风场特征的新阵风模型的建立提供理论基础和实验支持。

Small-scale wind turbine operations within the urban environment are exposed to high levels of gusts compared to flows over less rough surfaces. There is therefore a need to study the characterization of gust in the urban environment. In this study a 12-month wind resource measurement campaign was undertaken at a building location in the city of Hohhot in Inner Mongolia.While the gust factor, the gust amplitude and the excess energy content of 6 points at the top of the building with height form 0.8 m to 6 m were obtained. Therefore, the characterization of gust in the urban environment was understood. The results show that gust factors of 6 points were found to be higher at low wind speeds and lower at high wind speeds, indicating a decaying behaviour of gust factors with increasing wind speeds. And the IEC gust factor is underestimated at this site possibly leading to a turbine which is not appropriately designed for operating in the urban environment. For the 6 points, extreme gusts that satisfied the IEC definition of the gust amplitude bigger than 9.8m/s were not or very few found to occur during the 12 months interval. While the excess energy content of 6 points decreased with the increase of the average wind speed, and the excess energy content would increase with the increase of the height from the top of the building or the appropriate distance from the edge of the building. Thus, it is possible to obtain more excess energy if the wind turbine is installed in these places. The above results can provide theoretical basis and experimental support for the establishment of a new gust model suitable for the urban environment.