【作者】 李鹍；

【导师】 孙九林； 余庄；

【作者基本信息】 华中科技大学 ， 建筑设计及其理论， 2008， 博士

【摘要】 在我国的夏热冬冷地区,夏季炎热的气候条件使不少城市难以达到宜居环境的标准,城市热环境成为关注的焦点。城市热环境问题包括城市气候、城市规划、城市下垫面组成等多方面的因素,涉及多学科的研究领域。本文在夏热冬冷地区的气候条件下,以武汉市为例,采用RS(Remote Sensing)遥感技术、CFD(Computational Fluid Dynamics)仿真技术等数字化的城市研究手段,探讨城市热环境运行状况,解析城市热岛结构,并在城市规划层面找到相应的热环境改善措施。RS遥感技术具有全面、周期性观测的优势,其热红外反演技术可以较好的通过相关卫星影像反演地表温度、蒸散量、植被指数等热环境相关参数,并结合下垫面的性质和组成情况进行热环境分析。此外,该技术还可以为后续的CFD模拟研究进行修正参数、对比修正模拟结果等工作。CFD流体力学仿真技术具有流体分析的优势,借助对城市风环境的模拟研究,可以分析城市大气边界层与热环境的关系,了解热环境运行状态。还可以针对概念性设计方案和优化方案进行模拟研究与评估。两种技术相结合进行的城市热环境研究可以相互支持、相互弥补不足,成为紧密的热环境研究体系。本文以上述思想为基础,着重研究了以下主要内容:(1)首先研究了热环境研究的缘起、研究背景及研究意义等问题。然后通过对国内外相关研究进展的研究,发现本研究目前是学科发展中具有创新性的重要课题。现阶段虽然应用数字化方法的研究较多,但是多限于单一学科的研究,缺乏交叉学科、多技术手段的综合研究,这也是本文的出发点和创新点。(2)讨论了与城市热环境相关的各类因素:气候、城市边界层、城市下垫面、热环境指标。城市热环境在城市边界层产生,受气候、下垫面等因素的影响。对城市的热环境问题进行系统和详细的分析,找出城市的热环境与城市气候、城市下垫面之间的关系,为后续的数字化研究确立研究基础。(3)建构了城市热环境研究的数字化方法。该方法在收集了数据资料的基础上,采用遥感技术、CFD仿真技术进行结合研究。遥感技术主要通过对地表温度、蒸散量的反演结合下垫面参数进行城市热环境的研究;CFD仿真技术通过建立城市数字模型和流体模拟,进行相关的城市热环境模拟。(4)利用上述数字化方法,进行了基于遥感技术的城市热环境研究。通过遥感影像选择、数据预处理、地表温度反演等过程介绍了城市热岛反演的方法。此外进行了城市热岛与植被等城市下垫面关系的研究。然后以武汉市为例,进行城市热岛结构、典型地物及区域的分析等范例研究。为了使研究更全面,还进行了不同时间段城市热岛变化研究和夏热冬冷地区其它城市的城市热岛对比研究。其后进行了城市自然下垫面的蒸散量研究。蒸散值虽然不能直接反映热环境状况,却能结合地表温度体现蒸散吸收热量,改善城市热环境的作用,并可以借用来提高CFD模拟的准确度。文中介绍了蒸散的求取模型、求取过程和与地表温度的相互关系。(5)然后本文根据遥感研究的相关结论,研究CFD模拟的参数设置方法。参数设置是CFD模拟的核心,传统的参数设置方法设置简单,但结果不准确。本文利用遥感技术修正CFD的参数设置,使其更符合城市热岛的结构和特征,各相关因子更为合理。(6)利用经过遥感技术的部分结果和因子对CFD模拟的参数设置改进后的数字模型模拟分析城市热环境状况。在通过流体力学分析了城市整体热环境的基础上,进行了城市水体与热环境关系研究、城市通风道研究等热环境子项分析。通过上述研究发现,CFD运动流体力学技术适合于分析研究有关流体运动的问题,应用其来分析城市的风环境状况,进而探讨城市的温度场、居住环境、热岛状况等问题,是一种非常新颖而有效的研究方式。基于数字化空间信息集成技术的城市热环境研究,是城市环境管理和调控的有效手段,也是城市规划及环境科学研究的一个崭新领域和重要方向。本文所提到的遥感技术和CFD仿真技术在目前的实际规划项目中应用还比较少,在目前国家着重提出科学规划方式的前提下,大力发展这套研究方法并推动其与实际规划项目相结合具有非常重要的意义。更多还原

【Abstract】 In hot-summer and cold-winter zone in our country, Human in quite some cities is confronting the challenge of living difficulty due to the dramatically changing climate. Related problems including living situations ( especially in summer ) and heat environments are becoming a focus. The problems of city heat environment include city climate, city planning, city underlying surface and so on and are related to multidisciplinary fields. Basing on Wuhan, a typical city in hot-summer and cold-winter zone, the research presents the digit technologies on remote sensing (RS) and computational fluid dynamics (CFD) and a detail was shown in the running status of the heat environments and structure of heat islands. Other aspects including analyzing the structure of heat islands and seeking for corresponding measures in urban planning are also displayed.The RS technology shows the advantages of a comprehensive and periodical observation and the thermo-infrared of RS image using to inverse the surface temperature, the evapotranspiration and the vegetation index, as well as to conduct the environment analysis in accordance with the property and structure of underlying surfaces. Furthermore, the RS technology is capable of reversing the parameters and results for the CFD technology. The CFD has the advantage of conducting fluid analysis. It can present the relationship of a distinct boundary layer in the city atmosphere, the heat environment and the running status of heat islands using the simulation of wind. Additionally, it can evaluate the design of the conception and optimization via simulation. Combing both technologies on studying heat environments would support with one another and thus is a tight research system. Basing on such a thought, the main work of the dissertation is show as follows.(1)Firstly, the derivation, background and definition of the heat environments are studied, followed by summarizing relevant literatures. It can be concluded that such a research has its unique. Though there have been some digitization methods available, some are limited to the single subject and thus are lack of comprehensive studies with multidisciplinary backgrounds and comprehensive technologies. This is one of flashpoints in this dissertation.(2)Quite some issues relating to the heat environment are mentioned, such as the climate, atmospheric boundary-layer, underlying surface and the index of heat environments. The heat environment can be derived from the boundary layer and is influenced by the climate, underlying surface and so on. We are trying to find the relationship among the heat environment, city climate and the underlying surface using a systematic analysis and correspondingly establishing a foundation for the subsequent digitization.(3)A digitization method for the research of city environment is established. Such a method combines the RS with the CFD expect for the data collection. The RS is used to study the heat environment by inversing the land-surface temperature and the evapotranspiration, and by combining underlying surface’s parameters into research. Meanwhile, the CFD is used to simulate the heat environment by setting up a digital and fluid model.(4)Basing on the digitization method, the RS-based heat-environment research is conducted. Such studies include these steps such as the choice of RS images, data pretreatment and land-surface temperature inversion. The relation between heat island and underlying surfaces are discussed, including the underlying-surface index and extraction. Moreover, the structure of the heat island and the typical surface are also presented using Wuhan as the reference. As a result, there are complete researches on various stages and cities which cover in hot-summer and cold-winter zone. The evapotranspiration of the natural surface is also carried out. Although the evapotranspiration can not directly reflect the heat situation, it absorbs heat and thus improves the heat environment. Thus, such a method can be used to increase the accuracy of the CFD simulation. The model of acquiring the evapotranspiration, the running process and relationship with the surface temperature is discussed.(5)Based on related conclusions, the study examines boundary condition settings of CFD simulation, which is the key of the CFD simulation. The setting of traditional boundary conditions is simple but is lack of precision. To overcome such drawbacks, we have modified the setting by using the RS technology, thus making the simulation better matching to the structure and characteristic of heat islands. (6)Using the digital model reversed by the RS technology, the study also surveys the heat situation, the relation between the water body and the heat environments, and the ventilation panel basing on the study results of flowing in the motion of atmosphere. The CFD is found suitable for the problem well in terms of flowing and thus is a new and efficient way regarding the analysis of the wind environment, the temperature field, the living environment and the heat-island condition.The study of the heat situation basing on the spatial information technology is efficient in city environmental management and control. It is an important field in city planning and environmental sciences. The RS and the CFD technologies using in the study are less used for real planning projects. In the precondition of scientific planning methods mentioned greatly by local government, promoting this research method and combing it with real planning project appear to be meaning.更多还原