Wind Tunnel Test And Numerical Study On Wind Load Characteristics Of Diffuser High-rise Buildings

In modern cities,the high-rise buildings spring up with characteristics of high density and mass for land resources and a better city landscape.Standards concerning on wind load of most countries,however,is only applicable to individual building,and hardly involve group buildings with interference effect.The research about wind field characteristics of the group buildings will contribute to urban high-rise buildings layout,the integrated design of building and wind energy utilization,which is conducive to solve the problem of energy supply in high-rise buildings related to green-buildings as such.Under the condition of B-type terrain roughness,the paper focuses on the wind flow and load characteristics of diffuser high-rise buildings with square cross section via combining wind tunnel test and numerical simulation methods.Considering wind angles of attack and the distance between buildings,the experiments adopted the rigid models with scale ratio of 1:300,of which wind pressure on building surface,increasing effect of wind speed,interference effect and the base force features of the diffuser buildings with chassis structure were discussed deeply.Further in simulation,full-scale numerical models were established and Large Eddy Simulation(LES)was employed to explore the flow field characteristics and other aerodynamics around the diffusion for different length-width ratio mainly.Analyzing and comparing the results of wind tunnel test and numerical simulation,the study found that: 1)Gradient of the average wind pressure in channel flank is negatively correlated with wind angle for diffuser high-rise buildings.The side channel of disturbed building suffers from upstream building,especially the front part of channel,but the interference effect weakens with increased distance,pulse peak and extreme points of wind pressure gradually move from leading edge to the center of channel.In addition,wind pressure on the windward side ispositively correlated with the width and the maximum occurs near the 3/4height of the building.2)The diffuser high-rise buildings have an obvious enhancement effect on the wind speed at the range of wind angle from 0° to30° and the effect is significant for windward side width.Wind speed will reaches to a peak with the increase of distance and the maximum distributes in the range of 2/3~5/6 building's height.3)For diffuser high-rise buildings with chassis structure,the peak value of cross-wind force occurs when wind angle is 0°,whereas it is 60° at along-wind direction.The peak of cross-wind power spectrum distributes in the frequency range of 0.18~0.21,and is positively related with wind angle.Meantime,the wind force coefficients present a better symmetry for a symmetrical cross section,and what's more,affected by the building upstream,basal force of disturbed building will be significantly reduced and has a linear relation,sloping about 0.505,with length-width ratio.