CN 11-5366/S     ISSN 1673-1530
“风景园林,不只是一本期刊。”

智慧城市中的风设计

Wind Design in Smart Cities

  • 摘要: 随着城市密度变大,越来越多高层建筑的出现导致了步行高度上风速的增加,降低了行人舒适感和整个社区环境的吸引力。城市内的平均气温同样随着城市密度的增加而升高,难以降低的温度导致死亡率的提升。可以通过增强街道通风和散热等方式给城市降温,从而缓解这类问题。Actiflow对政府部门的建议为:1)在评估风对所在城市的影响时,须同时考虑其他因素;2)确定城市中的关键区域,设想如何应对其所面临的挑战;3)确定需要达到的品质标准;4)将大尺度上的解决方案及品质要求转化为实际操作导则。 一般来说,城市环境下的风参数评估技术有3种:实景测量、风洞实验和CFD计算机模拟(也称CFD或计算机流体力学)。对于城市中完整的风参数评估来说,实景测量并不是最佳选择,而CFD与风洞实验相比的主要优点为:1)能将整个风场可视化,而不仅是安装了传感器的离散点;2)即使是阳台或其他私人区域周边细微的空气流动都可被研究。CFD的最大缺点在于当模拟风的动态特征发生时(例如狂风等情况),就会由于计算量太大而变得非常困难。  荷兰NEN8100标准描述了2种评估步行环境风舒适度的方法:风洞实验以及CFD计算机模拟。Actiflow基于这项标准在风参数评估领域积累了相当丰富的经验,其中一个案例便是阿姆斯特丹附近的Amstel III区域。Actiflow向市政府提供了在公共场所缓解风障碍和危险的可行措施,并为该地区的房地产开发商们制定了详细的导则。

     

    Abstract: Cities become denser. We build more and more high-rise buildings, but these buildings typically induce high wind speeds on pedestrian level. As such, high buildings can reduce pedestrian wind comfort and the attractiveness of an entire neighborhood. As cities become denser, the average temperature in our cities increases. Increased temperatures lead to an increased mortality. Wind can help to ventilate streets and dissipate heat. Smart cities are advised to the four aspects: 1) Assess the impact that wind has in your city, but also look at other aspects. 2) Determine the critical areas, and consider how the challenges can be solved. 3) Determine which quality standards you want to achieve. 4) Translate the large-scale solutions and quality requirements into practical guidelines. In general, it can be stated that there are 3 technologies to assess wind in the urban environment: real life measurements, wind tunnel experiments and CFD computer simulations (CFD or computational fluid dynamics). For a complete wind assessment in a city, real life measurements are not recommended. The main advantages of CFD over wind tunnel experiments are: 1) You can visualize the entire wind field, and not only at a few discrete locations. 2) All details in the flow around small balconies or other private places can be studied. The main disadvantage of CFD is that dynamic wind effects like gusts are very hard and computationally expensive to simulate.This Dutch NEN8100 norm describes 2 ways to assess the wind comfort: wind tunnel experiments and CFD computer simulations. The results of the measurements or simulations are combined with local statistical wind data, in order to produce a map with local wind classes. Actiflow is a Dutch consulting company that has extensive experience in performing wind studies according to the NEN8100 norm. An interesting example is the wind study for the Amstel III region near Amsterdam. Actiflow advised the municipality about possible measures in the public space to mitigate wind hindrance and danger and formulated concrete guidelines for individual real estate developments in the area.

     

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