The Research On The Change Regulation Of Relative Humidity Effects Cause By Urban Lake Based On CFD Model

As a special underlying surface type in the city,the lake has good ecological benefits.However,with the acceleration of urbanization,urban environmental problems have become increasingly prominent,and urban lakes have undergone transitional development.Studies have shown that the number and area of lakes in cities are gradually decreasing.Urban lakes play a significant role in improving urban thermal environment due to the basic characteristics of their water bodies.Humidity index is one of the important microclimate factors,which can reflect the microclimate quality of the surrounding environment to some extent.In order to accurately grasp the impact of urban lakes on the surrounding environment,the fixed-point measurement and CFD simulation method were used to study the variation law and simulation of urban lake humidity effect with the lakes of Hunan Martyrs Park as the research object.The results are as follows:(1)Research on the variation law of lake humidity effect based on fixed-point measurement.Select 12 observation points from 4 sample lines around the lake,select 3 days per month,observe 10h every day(8:00-18:00,observe once every 1h),and observe for 1 year(2016.8-2017.7).The results show that:?The lake has a certain regulation effect on the air humidity in the surrounding area,and this regulation is negatively correlated with the distance from the lakeshore.? The daily variation of humidity is mainly affected by solar radiation.The humidity value in the early morning is higher than the humidity at noon;the average humidity in autumn and winter is higher than that in spring and summer.?Different environmental factors(such as vegetation,construction,transportation,etc.)can affect the lake humidity effect.(2)CFD simulation study of lake humidity effect.Based on the model of Hunan Martyrs Park Lake and its surrounding area of 400m,a calculation area containing water bodies and buildings was established.The data model was built by CFD simulation technology to simulate the humidity effect of urban lakes.The results show that:?City lake has a dampness effect on its surrounding environment,and the humid air spreads from the lake to the surrounding area.This effect is negatively correlated with the distance.As the diffusion distance increases,the wetting effect gradually decreases;it is positively correlated with the area.The larger the lake area,the greater the diffusion of humid air,and the stronger the lake wetting effect.?Wind is the main factor affecting the phlegm effect.The relative humidity value of the lower wind direction area is higher than that of the upper wind direction area,and the relative humidity difference between the two areas can reach 8.8-9.6%.At the same time,the area with a large wind speed usually has a relatively small air humidity.?The layout of the building affects the wind environment,which in turn affects the change in air humidity.Buildings block the airflow and hinder the diffusion of water vapor.When the layout of the building is parallel with the dominant wind direction or the angle is small,the ventilation is better;when the layout of the building is perpendicular to the main wind direction or the angle is too large,or the layout is messy,it is easy to form a large area of static wind.(3)CFD simulation study to change a single factor.The results show that:?Under the scenario of changing the lake area and other conditions,the size of the lake area is positively correlated with the humidity field of the surrounding environment.The larger the lake area,the greater the dampness effect and the influence range.The effect of the change in area on the wind speed field is limited.? Under the situation that the surrounding building environment is changed and other conditions are unchanged,after the building receding distance increases,the wind environment of the windward area is improved,but the humidity field changes are not obvious,and the humidity of the lake area and the downwind area has a certain degree of decline.The scope of the lake humidity effect has been reduced;after the building spacing increases,the wind speed field has a significant improvement effect,and the impact on the humidity field is small,the humidity value of the whole area is slightly reduced,but the lake has a surrounding environment.The air humidity still has a good regulation effect;after the height of the building increases,the blocking effect on the airflow is greatly enhanced,and the humidity distribution of the entire calculation domain is uniformized,resulting in a significant decrease in the humidity in the lake area and the downwind area,and the humidity effect on the surrounding environment.