Ventilation Potential Assessment And Ventilation Corridor Identification In The Central City Of Changsha Ventilation Corridor Identification

China’s rapid urbanization has had a negative impact on urban wind and urban environment,with the heat island effect,air pollution and other "urban diseases"becoming increasingly serious.In recent years,Changsha’s urban area has been intensively built up,ecological space has been destroyed,and the climate environment needs to be improved.In order to improve the climate environment in the central city of Changsha,we provide guidance for the design and construction of future ventilation corridors,and provide a new basis and method for the ecological design of landscape and green space ecosystems.This study takes the ventilation system in the central city of Changsha as the research object,uses the computational fluid dynamics simulation software CFD to evaluate the current situation of this ventilation system,evaluates the ventilation efficiency with the surface morphology and thermal factors as indicators,and constructs the ventilation corridor system under the typical summer sunny monsoon conditions in the central city of Changsha system,and the main findings are as follows:(1)The spatial distribution of ventilation potential in the urban areas of Changsha city decreases from the periphery to the center,and the differences are generally small.Most of the areas with poor ventilation potential are located in Tianxin District and Yuhua District,which are the areas with the highest urban construction intensity in Changsha,with extremely high building density and many high-rise buildings distributed,which have the greatest obstruction effect on urban wind.(2)The scenario simulation results of different wind directions are integrated to identify 16 ventilation corridors,construct a three-level ventilation corridor system,and calculate the ventilation performance of the corresponding corridors.The plan form and composition of the wind corridors are various.The corridors with good ventilation performance are mainly composed of green open space and located in areas with low building density,while the corridors with poor ventilation performance are mainly composed of roads and building height differences in the urban area and located in areas with high building density.Most of the ventilation corridors are located near Xiangjiang River,and one of them is dominated by Xiangjiang River.(3)The optimized solution was tested by construction and scenario simulation,and it was found that the overall wind speed of the optimized solution was improved,with the highest wind speed value reaching 2.42 m/s.The optimized solution has significantly improved the overall ventilation environment.The central part of the study area is the area with the highest building density.By expanding the cross-section of the ventilation corridor and adding new green open space,more fresh air is introduced into the building complex,which reduces the blocking effect of the buildings on the dominant wind and strengthens the ventilation function of the ventilation corridor,so that the wind speed in the building complex can be increased and the wind environment can be improved.(4)The six factors affecting the ventilation potential,namely,topographic conditions,rough length,road conditions,built environment,open space and water system,were analyzed by using a geographic probe,and it was found that rough length and built environment,among the six factors,had the greatest influence on the ventilation potential,indicating that rough length and built environment could be important determinants of the spatial distribution of ventilation potential.The other four factors also have significant effects on the ventilation potential,in descending order of influence:road conditions,open space,water system,and topographic conditions,and the effect of these four factors on the ventilation potential is weaker than that of rough length and built environment.