Study On The Quantitative Simulation Of Urban Ventilation Channel In Block Scale And Its Parameterization Of Planning Indices

With the rapid development of urbanization and social economy,the urban climate environment is facing a series of treats and challenges.Since the 20th century,the frequent occurrence of various air pollution incidents,the urban haze and urban heat island effect are becoming general problems,which are warning people to pay attention to the urban climate environment.The urban ventilation channel is an important part of research on urban climate environment,and attachs a profound impact on the development and evolution of urban haze,urban heat island effect and urban climate environment.It affects people’s physical and mental health from different scales of the city,the block and the building.However,in the current situation,it is difficult to conduct an urban ventilation channel because of the absence of consideration on urban ventilation.At the same time,the waste heat and pollutants produced by human activities have not been effectively diluted,thus affecting the sustainable development of the city.In addition,due to lack of data support,the planning and implementation of urban ventilation channel is also more difficult.Therefore,it is more and more urgent to carry out the quantitative simulation of urban ventilation channel,and provide the support for its planning and implementation.In this paper,in order to explore the planning indices of urban ventilation channel and parameterization,some models have been constructed to quantify factors of urban ventilation channel type,the width of channels and the height of buildings.This paper describes the theory and methods of research on urban ventilation channel.The urban ventilation channel is mainly divided into the types of the road ventilation channel,the Greenland ventilation channel and the water ventilation channel.It is proposed to distinguish and quantify the different types of ventilation channels through the roughness of dynamics.Then the paper puts forward the viewpoint that the ventilation effect is mainly affected by the internal factors such as the width,the height of buildings and the ventilation channel type.At the same time,the strategy that using the technologies of geographic spatial data assimilation,ventilation simulation coupling,CFD numerical simulation,control variable method and fieldsurvey method forms.This paper nextly elaborates the control group constructed in the ideal condition.the paper firstly begins by constructing different ventilation channels to research on ventilation quality,then the simulation has been divided into three groups.The first group is simulated with a width variable,it needs five models,the width is the variable,composed of 30m,40m,50m,80m and 100m.There are three kinds of ventilation channel types are simulated,and the roughness of the urban road channel,the greenland ventilation channel and the water ventilation channel are respectively 0.0013m,0.0052m and Om.The height for the whole buildings is 48m.It needs to simulate fifteen times;The second group is with the variable of height.There are four models newly built,and their heights are respectively 24m,36m,60m and 72m.There are three types of ventilation channel have been simulated for twelve times(three of them have been conducted);The third group is with the variable of type,and the widths are respectively 30m,40m and 50m.The height of the buildings in these models are 48m.Finally,the results of the control group showed that among the three kinds of the ventilation channel type,the effect of the water ventilation channel is the best,the road ventilation channel comes second,and the greenland ventilation channel is the worst;The suitable range of the width is 50m to 80m,and 80m is the most suitable one;The height of the building has better range from 24m to 48m,and 48m is the best one.The next part of this paper is the experimental study on the actual models of Hangzhou urban ventilation channel.Choosing the downtown of Hangzhou in three typical types of urban ventilation channels,including Youth Square Area-Qingchun Road-Zijin community,Dong community-Moganshan Road-Mexican Garden,Spring Garden-West-Luo Jia Zhuang,Shannan People-on the Sea Garden,Garden community-Jing Fang,Zhaohui Sixiao District-Modern Gardens,Lu Jia He tou community,oasis garden area of peace,Fairview Park-Hong Park community,a total of nine ventilation channel models.The results showed that the order of ventilation efficiency fits with the control group’s,but the width and the height of buildings cannot be completely suitable for quantitative analysis and the optimal interval value can only determine the width of the ventilation channel.The higher the buildings is,the worse the ventilation effect is.According to the actual situation of Hangzhou City,the improvement strategies of wind environment are put forward.The paper lastly summarizes the conclusions,innovations,deficiencies and prospects.There are some aspects need to be improved.For example,the analysis of the influencing factors is not comprehensive enough,and the analysis of the type can also be furthered,some deviations can be reduced by improving the techniques and the methods.The paper also puts forward some prospects to improve the wind environment of Hangzhou City.