| As an important part of urban space,old blocks carry the memory of the city and are mainly composed of various spatial morphological elements such as buildings,streets and pavement.With the rapid development of urbanization,extensive development leads to the problems of dense buildings,lack of green,traffic congestion and other problems in old blocks,resulting in difficult ventilation and heat dissipation of blocks,and obvious heat island effect.How to improve the wind and heat environment of the old block and realize the improvement of its environmental quality has become a widespread concern.Although there are many studies on the renewal design of old blocks,there are few considerations on the spatial morphology of wind-thermal environment,and most of them are qualitative studies.Taking xiangtan city Station Road old block as an example,considering block building space form,the external factors such as climate condition,the green to the old blocks wind hot environment,the influence of extraction and quantitative factor,green space area,green space layout,ventilated corridor,roof greening,setting scene simulation,using ENVI-met model,simulation analysis of different wind thermal environment effect of quantitative factors,The improvement strategy of wind and heat environment in block is put forward and further optimized.The following contents are mainly studied:Firstly,the commonly used CFD simulation software for wind-thermal environment research was analyzed,the numerical calculation method and application scope were described,and the simulation software ENVI-MET suitable for this study was selected.Case samples were selected for comparative analysis of simulated and measured VALUES of ENVI-MET to verify its reliability in the study area.Secondly,through the field survey of several typical old blocks in xiangtan main urban area,it is found that the current spatial form of the blocks leads to poor wind and heat environment,which is in urgent need of improvement.In this study,the typical old block--old block of Station Road was taken as a case.According to the block scope and spatial form,the grid size,material,climate conditions and other related parameters of the simulated area were set.Envi-met software was used to simulate the current wind and thermal environment of the block and analyze the distribution of temperature and wind speed.The existing problems and possible influencing mechanism of wind-thermal environment are obtained.Next,status to plan as a benchmark,to extract the quantitative factor,green space area,green space layout,ventilated corridor,roof greening,analysis of different wind hot environmental improvement effect of quantitative factors,16 kinds of scene simulation model was constructed,using ENVI-met software were analyzed,clarify the related mechanism between each other,the research on the block wind the influence of thermal environment.It is found that the size of green space is very important to improve the wind and heat environment of the block.When the same amount of building area is removed,the cooling effect of scattered green space is the most obvious.Open space is arranged in the upwind direction of the dominant wind direction,which can gather a lot of external wind and greatly improve the wind environment in the surrounding area.The ventilation corridor parallel to the dominant wind direction can quickly lead the wind into the ventilation duct and improve the wind environment obviously.When roof greening is combined with plane green space,its cooling effect on the surrounding local area will be enhanced.Finally,according to the simulation analysis results of 16 scenarios,the improvement strategy of wind and heat environment in old blocks is proposed.First,the public green space planned for old blocks should adopt "scattered" layout as far as possible.Second,the potential ventilation corridors parallel to the dominant wind direction can be expanded with the demolition of a small number of buildings,such as the internal open space and streets.At the same time,a "V-shaped" open space can be constructed in the upwind direction of the ventilation corridor,which can promote the improvement of wind speed.The third is to optimize the ecological base of the underlying surface of old blocks;Fourth,the combination of roof green space and open space such as plane green space and square can enlarge its cooling effect.Research based on improvement strategy about the present situation of the old Station Road blocks modification and optimization,space form,using ENVI-met software simulation optimization thermal environment wind,analyzed and compared with the status quo,the simulation results show that optimized green space area,green space layout,ventilation,corridor,roof greening,etc can improve the thermal environment,wind block In this way,the practice and planning design of the renewal of old blocks based on the improvement of wind and thermal environment are guided,and the guidance with strong pertinence and high implementation degree is put forward for the renewal design of old blocks in the future. |
