Numerical Simulation Of Downburst Wind Analysis

Downburst is a common phenomenon of strong convective weather, sometimes forhuman activities will cause some impact, even bring some disaster. Priorresearch to thedownburst mainly applied in meteorology and aviation field. There is little researchcontraposed the building on the downburst winds and downburst wind loads. Theloadcodein China did not involve the extreme weather such as downburst.This paperattempts to adopt numerical simulation CFD methods to investigate the law ofdownburst winds, consider the influence of topography, study the characteristics ofdownburst winds in mountainous topography and laythe foundation for wind tunnel test.Through the analysis, this thesisdrawsthe following conclusions:（1）Firstly, by using a variety of turbulence models to simulate, select the RNGk-εturbulence model which was consistent with the existing measured and theoreticaldata to do the following research work. The simulation results shows that at differentradial positions the wind profile is different, but the normalized results correspond to thetheoretical and experimental models. The outflow speed of downburst has little effect onwinds；The impact of the downburstcenterdiametertothe winds is limited to the size ofthewind field, and the downburstcenterdiameter has no influence to the wind profile.Theratio—height of downburst/downburstcenterdiameter（H/D）make a strong impact onthe wind profile, but normalized wind profile was consistent.It illustrates that thedifferent downburstcenterdiameter maintain the basic characteristic of downburst.（2）According to loadcode8.2.2, the escarpment topography is be considered indownburst winds. In the top of the escarpment there is a significant acceleration effect.At the the0.075D distance after the top of the escarpment, the wind profile has beenfound to substantially coincide with the flat wind profile, thereby the impact of thetopography has almost disappeared. The size of slope impacts the winds obviously, thegreater the slope, near-Earth region that Z <0.04m forregional acceleration effect ismore obvious. Changes in the position of a hill there is a certain influence on thedownburst winds. The blowing speed of downburst barely influence the downburstwinds, the H/D value influence the acceleration region size, and has no impact on thewinds.（3）The accelerating on the top of cosine-shaped mountain is smaller than theescarpment,but for the effect of topographyin wind,the cosine-shaped mountain is more obvious than the escarpment.The velocity in the center of downburst has no impact onthe downburst wind.The effect of H/D values in downburst is similar to the escarpment,The results obtained with the different slope of the cosine-shaped shows that thedifferent of terrain does not change the characteristics of the wind farm. Changing theposition of the mountain and found the same acceleration curve trend factor, butdifferent sizes, with the crest of the peak acceleration factor is the position of thedistance to the center of the storm increases.