| With the development of modern buildings in the direction of towering and large spans,the sensitivity of buildings to wind loads has been paid more and more attention.For the wind tunnel test,there are problems such as greater cost of consumption,longer time spent in the test preparation stage,and the use of the scale ratio model will bring similar ratio problems and the limited number of measurement points arranged.The CFD(Computational Fluid Dynamics)numerical simulation method is used,which requires less time and cost than the wind tunnel test.The numerical simulation can construct a calculation model with the same size as the actual size,and can obtain the values and development of all variables in the entire calculated watershed History,and the results are very intuitive.Among them,Large Eddy Simulation(LES)is an important technology for studying turbulent motion in computational wind engineering.In this paper,large eddy simulation studies are conducted on the airflow of atmospheric boundary layer of Guangzhou CGB-2 under construction wind tunnel and the surface wind pressure of the towering structure.Using large eddy simulation technology and artificial blockage device to debug the wind field of Guangzhou CGB-2 wind tunnel.Random Number Recycling Method(RNRM)was used as the entrance boundary condition for large eddy simulation to study the flow field distribution characteristics,vortex-induced vibration and aerodynamic measures using wind-breaking loops around thetowering structure.The main research contents and conclusions of this article are as follows:1.Establish a full-scale model of the test section of the Guangzhou CGB-2 wind tunnel,and use the artificial blockage device of spires and roughness to study the large eddy simulation of the airflow of atmospheric boundary layer in the wind tunnel.Firstly,large eddy simulation was conducted on the Tongji TJ-2 wind tunnel test section C type geomorphic artificial blockage device to verify the feasibility and correctness of using the large eddy simulation technology and artificial blockage device to simulate the airflow of atmospheric boundary layer in the wind tunnel.Secondly,the preliminary design of the spires and roughness of the CGB-2wind tunnel test section in Guangzhou,and the layout of the wind tunnel were designed.On this basis,the wind field test was carried out on the CGB-2 wind tunnel test section in Guangzhou.Finally,the size and sharp of spires and roughness of the four types of landforms in China’s specifications were given.2.Random number recycling method is used to generate atmospheric boundary layer turbulence as the inlet boundary condition of large eddy simulation,and the large eddy simulation study is carried out on the case of no model calculation domain and the CAARC model calculation domain.The results are compared with specifications,it is found that the characteristics of the atmospheric boundary layer flow field at the model location are in good agreement with the specifications,which verifies the correctness of the inflow conditions at the model.The numerical simulation results of the calculation domain with the CAARC standard model are compared with the wind tunnel test results,and it is found that the average wind pressure coefficients and pulsating wind pressure coefficients on the windward,crosswind and leeward surfaces generally agree well with the test results.The applicability and accuracy of the random number recycling method as the inlet boundary conditions for large eddy simulation are verified.3.Using the random number recycling method as the inlet boundary condition of the large eddy simulation,the large eddy simulation study of the towering structure is carried out.By analyzing the flow field and lift coefficient at different section heights under different wind speeds at the top of the tower Spectral characteristics determine that the actual critical top wind speed at which the vortex-induced resonance of the towering structure o is 63m/s.Moreover,explore the anti-wind effect of the aerodynamic measures of the windbreaker to reduce the wind load.The windbreaker can effectively destroy the vortex shedding of the heat absorption tower,reduce the crosswind load on the structure surface,and avoid the crosswind direction vortexinduced resonance of the structure.4.Use the large eddy simulation to obtain the wind-pressure time series of the measuring points on the surface of the towering structure,and analyze the wind vibration response to explore the influence of the top wind speed,wind direction angle,damping ratio and windbreaker on the wind vibration response.By analyzing the wind-induced vibration response of the towering structure under different wind direction angles,the most unfavorable wind direction angle of the structure is determined to be 75°.At various wind direction angles,the crosswind vibration response caused by vortex shedding is greater.As the wind speed at the top of the tower increases,the wind-induced vibration response also gradually increases.As the damping ratio increases,the tower top displacement,base shear and base bending moment gradually decrease,and the damping ratio of 0.15% to 1% has a greater impact on the windinduced vibration response.The recommended range of damping ratio is 0.15% to 1%.After adopting the windbreaker,the wind vibration response is significantly reduced and the average reduction is 39.3%.Setting the windbreaker can effectively reduce or even eliminate the influence of the crosswind vortex-induced resonance of the towering structure. |
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