The Analysis Of Influence Of Building On Wind By Observation Experiment And CFD Method

The article mainly analyzes the influence of obstacle on wind speed and wind direction using wind observation data between August2012and November2013,meantime Computational Fluid Dynamics method and sensitivity analysis are used for assessing requirements for the distance of the obstacles quantitatively, the choosing of station address is simulated in the end.The main results is as following:1.The article analyses the influence of the obstacle on wind velocity and wind direction by comparing northwest and southeast,south and north after the built of the building in Guyuan,Hebei Province. The results show that:(1) the obstacle can weaken the wind speed, which is related to baseline wind speed, and with great wind speed comes great effect extent.(2)When the angle between the wind direction and obstacle is90degrees,and the baseline wind velocity is less than3m/s,the attenuation ratio of wind speed is10-15percent or so at the distance of10times the height of the obstacle; as the baseline wind velocity is more than4m/s,the velocity value attenuates by about20-30percent at10times the height of the obstacle distance.(3) The wind speed attenuation ratio of the12.5degrees direction is bigger than that of the45degrees direction when the angle between the wind direction and obstacle is45degrees.(4)The prevailing wind direction frequency is decreased caused by the obstacle, and the influence distance is6times the height of the obstacle of90degrees,8times the height of45degrees.2.In order to evaluate the requirements for the distance of the obstacles from the anemometer,a set of numerical simulations and sensitivity experiments on an isolated building by CFD model were carried out.The results indicate that:(l)The range of90%inflow speed is3times the height of the building in windward side, and28.5times of it in leeward side.Meanwhile,the range of10°deviation to inflow wind direction is1.4times the height of the building in windward side,6.8times of it in leeward side,2.8times of it in lateral side and4times of it in vertical height.(2)By the sensitivity analysis of the influenced factors,the requirements for the ratios of the distance to the height of building at10meters are sensitive to inflow speeds, building thickness, building height, building angular width,inflow directions and temperature.The requirement for the ratios of the distance to the height of building of temperature measurement at1.5meters is sensitive to the baseline temperature.3.Variation of meteorological elements is studied after the detecting environment changing,using two models of Lvsi staion and the new address.The results show that:(1) both the CFD model and the Urban Scale Model can simulate the wind field correctly,and the error between them is less than10percent.(2)The wind speed attenuation ratio of Lvsi station is bigger than that of the planned new address,and the new address can better reflect the natural state of the wind observation.