Study On The Impact Of Vegetation Greening On The Surrounding Environment

With the economic development,China’s urbanization has become increasingly accelerated.Many cities have become more and more serious due to excessive building density and excessive population density,which has a greater impact on people’s lives.Trees can cool down and humidify,alleviate the "heat island phenomenon",improve the thermal comfort of urban residents,and also play a role in preventing wind and sand and absorbing pollutants.This paper studies the common trees on campus,combined with wind tunnel test and numerical simulation,quantitatively studied the effect of canopy resistance and cooling and humidification.The main research contents are as follows:(1)Five common plant species(Lotus magnolia,Osmanthus fragrans,Liquidambar formosana,Eucalyptus and Lamei)were used to study the relationship between canopy structure parameters by wind tunnel test.The results showed that there was a direct relationship between the leaf area index(LAI)and the filling rate(SVF)of the five canopies.According to the test results,an expression of the conversion relationship between the leaf area index and the filling rate of common plants on campus is given.(2)Based on the experimental study of canopy structure parameters,the relationship between canopy flow resistance and leaf area index and wind speed was further quantitatively explored.The multivariate regression of the experimental data was carried out to obtain the multivariate relationship expressions of the flow resistance and leaf area index of the five leaves and the wind speed,and the prediction results of the expression were in good agreement with the experimental results,only when the wind speed was small(v≤0.5m/s).The deviation between the predicted results and the test results is obvious.(3)The plume was used as a test sample to conduct a wind tunnel test to study the relationship between the cooling and humidifying effect of the plum and the supply air temperature,leaf area index and wind speed.The results show that the plum can effectively cool down and humidify.By multivariate regression of the experimental data,the expression of the multivariate relationship between the cooling amount and the humidification of the plum is obtained,and the prediction results of the expression are in good agreement with the experimental results.(4)Based on the wind tunnel test,the numerical calculation software CFD is used to treat the canopy as a porous area.A numerical model describing the flow resistance effect and cooling effect of the canopy is proposed.The results show that the numerical simulation results are in good agreement with the experimental data and can be used for Study the effect on the flow resistance and cooling of the canopy.