低层双坡屋面建筑三维定常风场的数值模拟

NUMERICAL SIMULATION OF 3D STEADY ATMOSPHERIC FLOW AROUND LOW-RISE GABLE ROOF BUILDING

基于计算流体力学软件Fluent6.3,首先,选用基于Reynolds时均的标准k-ε等湍流模型对大气边界层中TTU标模的低层建筑三维定常风流场进行模拟分析,并将数值模拟结果与场地实测数据和TJ-2风洞试验结果进行了比较分析;其次,采用RNGk-ε模型分析了不同风向角下,房屋屋面坡度、挑檐长度、檐口高度和长宽比对低层双坡房屋屋面风压系数及各表面体型系数的影响。结果表明:数值模拟较好地反映了低层建筑周围风环境的绕流特性和表面风压的分布情况;迎风墙面均受有正压力,其体型系数受房屋几何尺寸的影响较小,房屋的背风面均承受负压力;屋面坡度及檐口高度对屋面风压分布及风压大小均有明显的影响,挑檐长度的影响较小;屋面的平均风压系数分布和大小与风的来流方向有关。该结论为低层房屋的工程抗风设计提供了依据。

A standard k-ε model,the Reynolds Averaged Navier-Stokes Equations（RANS）turbulence model,is added in a commercial computational fluid dynamics software Fluent 6.3 to numerically simulate the 3D steady wind flow field around standard low-rise building TTU in atmospheric boundary layer.The simulating results are compared with TTU field measured data and Tongji University TJ-2 wind tunnel test data.Then a detailed parametric study is performed for average pressure coefficient and shape factors of low-rise building with gable roof by RNG k-ε turbulence model.The parameters include wind attack angle,roof pitch,eave length,eave height,and ratio of wall length to width.The analysis results show that numerical simulation is a feasible way to study the wind flow around low-rise building and the distributing of wind pressure in the building＇s surface.The pressure on the wall of windward is positive,and its shape factor isn’t affected by the geometry of building.The pressure on the wall of leeward is negative.Wind attack angle,Roof pitch and aspect ratios of wall length to height affect both the magnitude and distribution of gable roof pressures;the eave length doesn’t affect the roof pressures.The research provides a foundation for the wind resistance design of this type of buildings.