湍流积分尺度对高层建筑风荷载影响的大涡模拟
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摘要
为研究湍流积分尺度对高层建筑风荷载大小和分布的影响,研究其合理取值,基于大涡模拟开展了B类地貌不同湍流积分尺度下CAARC(commonwealth advisory aeronautical research council)标准高层建筑模型绕流模拟,并将模拟结果与风洞试验进行了比较.研究结果表明:大涡模拟能较好地反映高层建筑周围风场绕流特性和表面风压分布.随着湍流积分尺度的增大,平均运动的变形率向湍流脉动输入能量,以致平均风速降低、湍流强度增大;侧面风压脉动性降低15%、分离流附着提前出现;基底扭矩谱和弯矩谱的峰值及高频段幅值均减小;层斯托罗哈数在0.4倍建筑高度以下基本相同,随高度的增加其值下降20%~30%;层平均阻力系数下降5%~10%;迎风面风压系数平均值下降2%~5%,侧面和背面下降12%~17%.湍流积分尺度对迎风面和侧面上风向的风压水平相关性、层升力和0.8倍建筑高度以下的层阻力相关性的影响可以忽略.随湍流积分尺度的增大,风压水平相关系数增大,背风面增大5%~10%,侧面下风向增大15%~25%,0.8倍建筑高度以上层阻力相关性系数增大25%~50%.B类地貌湍流积分尺度的调整系数为0.4时,计算得到的风荷载与试验结果趋于一致.
To investigate the influence of turbulence integral length on the wind pressure value and distribution on the surface of tall buildings and determine the reasonable value of turbulence integral lengths,a large eddy simulation( LES) was conducted under different turbulence integral lengths to represent the wind flow field around the commonwealth advisory aeronautical research council( CAARC) standard tall building model in exposure category B. The obtained results were compared with those from the wind tunnel test. It is found that the LES is a feasible tool to represent the wind flow around a high building and the distribution of wind pressure on the building surface. It is also found that with the increase in the turbulence integral length,the energy of turbulent fluctuation increases,resulting from the deformation of flow average movement; the mean wind speed will decrease,and hence,the turbulence intensity will increase. It is also found that the fluctuation of windpressure decreases by 15% on the side face,while the reattachment point of separated flow moves forward. Meanwhile,the local peak at the high-frequency range as well as the peak of aerodynamic base moment and torque spectrum decrease. While the Strouhal number of the layer is essentially the same at a height lower than 0. 4 times the height of the building,it decreases by 20%-30% with the increase in height,and the drag coefficients of the mean layer decrease by 5%-10%. The results also show that the mean coefficients of the wind pressure in the windward side reduce by 2%-5%,with a decrease of 12%-17% in the crosswind side and leeward side. The investigation further finds that the turbulence integral length has minor effects on correlations of horizontal wind pressure in the windward side and crosswind side in the upwind direction,and the lift on the layer and drag on the layer at a height less than 0. 8 times the height of the building. With the increase in the turbulence integral length,the correlation coefficient of the horizontal wind pressure increases respectively by5%-10% and 15%-25% in the leeward and crosswind sides in the downwind direction,and the correlation coefficient of the drag of the layer increases by 25%-50% at a height above 0. 8 times the height of the building. When the adjustment coefficient of the turbulence integral length in exposure category B is 0. 4,the results of wind load obtained by LES are more consistent with the test results.
To investigate the influence of turbulence integral length on the wind pressure value and distribution on the surface of tall buildings and determine the reasonable value of turbulence integral lengths,a large eddy simulation( LES) was conducted under different turbulence integral lengths to represent the wind flow field around the commonwealth advisory aeronautical research council( CAARC) standard tall building model in exposure category B. The obtained results were compared with those from the wind tunnel test. It is found that the LES is a feasible tool to represent the wind flow around a high building and the distribution of wind pressure on the building surface. It is also found that with the increase in the turbulence integral length,the energy of turbulent fluctuation increases,resulting from the deformation of flow average movement; the mean wind speed will decrease,and hence,the turbulence intensity will increase. It is also found that the fluctuation of windpressure decreases by 15% on the side face,while the reattachment point of separated flow moves forward. Meanwhile,the local peak at the high-frequency range as well as the peak of aerodynamic base moment and torque spectrum decrease. While the Strouhal number of the layer is essentially the same at a height lower than 0. 4 times the height of the building,it decreases by 20%-30% with the increase in height,and the drag coefficients of the mean layer decrease by 5%-10%. The results also show that the mean coefficients of the wind pressure in the windward side reduce by 2%-5%,with a decrease of 12%-17% in the crosswind side and leeward side. The investigation further finds that the turbulence integral length has minor effects on correlations of horizontal wind pressure in the windward side and crosswind side in the upwind direction,and the lift on the layer and drag on the layer at a height less than 0. 8 times the height of the building. With the increase in the turbulence integral length,the correlation coefficient of the horizontal wind pressure increases respectively by5%-10% and 15%-25% in the leeward and crosswind sides in the downwind direction,and the correlation coefficient of the drag of the layer increases by 25%-50% at a height above 0. 8 times the height of the building. When the adjustment coefficient of the turbulence integral length in exposure category B is 0. 4,the results of wind load obtained by LES are more consistent with the test results.
引文
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[12]杨有根.高层建筑的抗风实测分析与大跨度屋盖的风致响应研究[D].长沙:湖南大学,2007.
[13]苏万林,李正农.湍流对超高层建筑风压幅值特性影响的研究[J].地震工程与工程振动,2016,36(3):118-126.SU Wanlin,LI Zhengnong.Research of turbulent effects on characteristics of wind pressure amplitude on tall buildings[J].Earthquake Engineering and Engineering Dynamics,2016,36(3):118-126.
[14]唐意.高层建筑弯扭耦合风致振动及静力等效风荷载研究[D].上海:同济大学土木工程学院,2006.
[15]陈建兰.矩形截面高层建筑风荷载试验研究[D].武汉:华中科技大学,2005.
[2]JR F L H,KAREEM A,SZEWCZYK A A.The effects of turbulence on the pressure distribution around a rectangular prism[J].Journal of Wind Engineering and Industrial Aerodynamics,1998,77-78(98):381-392.
[3]NAKAMURA Y,OZONO S.The effects of turbulence on a separated and reattaching flow[J].Journal of Fluid Mechanics,1987,178:477-490.
[4]LI Q S,MELBOURNE W H.The effects of large scale turbulence on pressure fluctuations in separated and reattaching flows[J].Journal of Wind Engineering and Industrial Aerodynamics.1999,83(1/2/3):159-169.
[5]Huang S H,Li Q S,Wu J R.A general inflow turbulence generator for large eddy simulation[J].Journal of Wind Engineering and Industrial Aerodynamics,2010,98(10):600-617.
[6]张兆顺,崔桂香,许晓春.湍流大涡模拟的理论与应用[M].北京:清华大学出版社,2005:4-42.
[7]罗盘.基于标准模型的风洞试验研究[D].上海:同济大学土木工程学院,2004.
[8]TAMURA Y,OHKUMA T,KAWAI H,et al.Revision of AIJ recommendations for wind loads on buildings[C]∥Structures Congress.Nashville:[s.n.],2004:1-10.
[9]LAKEHAL D.Application of the k-εmodel to flow over a building placed in different roughness sublayers[J].Journal of Wind Engineering and Industrial Aerodynamics,1998,73(1):59-77.
[10]MELBOURNE W H.Comparison of measurements of the CAARC standard tall building model in simulated model wind flows[J].Journal of Wind Engineering&Industrial Aerodynamics,1980,6(1):73-88.
[11]OBASAJU E D.Measurement of forces and base overturning moments on the CAARC tall building model in a simulated atmospheric boundary layer[J].Journal of Wind Engineering and Industrial Aerodynamics,1992,40(2):103-126.
[12]杨有根.高层建筑的抗风实测分析与大跨度屋盖的风致响应研究[D].长沙:湖南大学,2007.
[13]苏万林,李正农.湍流对超高层建筑风压幅值特性影响的研究[J].地震工程与工程振动,2016,36(3):118-126.SU Wanlin,LI Zhengnong.Research of turbulent effects on characteristics of wind pressure amplitude on tall buildings[J].Earthquake Engineering and Engineering Dynamics,2016,36(3):118-126.
[14]唐意.高层建筑弯扭耦合风致振动及静力等效风荷载研究[D].上海:同济大学土木工程学院,2006.
[15]陈建兰.矩形截面高层建筑风荷载试验研究[D].武汉:华中科技大学,2005.