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为揭示山区峡谷风场的空间分布特性以及峡谷地形对谷内风场特性分布的影响,根据山区峡谷的地形特点,在AutoCAD中将峡谷的几何模型离散为高程点云,利用逆向工程软件Imageware将高程点云拟合成峡谷地形曲面,并导入Gambit中生成满足要求的计算模型;应用FLUENT软件选取适合山区风场的Realizable模型,采用稳定性好的SIMPLE算法对峡谷风场特性进行数值模拟;最后根据峡谷地形特点和其影响参数,提出峡谷风速放大系数计算公式,并采用多个算例验证其正确性。研究结果表明:山区峡谷风剖面的轮廓线可以分成3段,不能套用平原地区常用的幂函数模型,并且峡谷风剖面的轮廓线具有明显拐点,风速增大段的风剖面轮廓线应采用线性函数与幂函数共同模拟;峡谷内中间位置风剖面最大风速大于两侧风剖面最大风速,其相应的风速拐点高度也较大;峡谷内同一高度观测点的风速在峡谷横断面上成抛物线变化,距离两侧山体约60m处风速达到最大值;峡谷越窄,两侧山峰越高,峡谷内风场的“峡谷效应”越明显;风剖面风速拐点高度与峡谷高宽比成反比,峡谷高宽比越大,风剖面风速拐点高度就越小;该公式可推算山区峡谷内任意高度的风速,可为跨越山区峡谷的桥梁抗风设计基准风速的计算提供简便方法。
In order to reveal the spatial distribution characteristics of the canyon wind field and the influence of the canyon topography on the distribution of the wind field characteristics in the valley, according to the topographic features of the canyon in mountain area, the geometrical model of the canyon is discretized as elevation point cloud in AutoCAD. The point cloud is fit into the gorge terrain surface and imported into Gambit to generate the computational model that meets the requirements. The realizable model suitable for the mountain wind field is selected by FLUENT software, and the SIMPLE algorithm with good stability is used to simulate the wind field characteristics of the gorge. Finally, Gorge topography characteristics and its influencing parameters, the calculation formula of wind speed amplification coefficient of canyon is proposed, and several examples are used to verify its correctness. The results show that the contour of mountain gorge wind profile can be divided into three sections, the common power function model can not be applied in plain area, and the outline of gorge wind profile has obvious inflection point. The wind profile contour of wind speed increasing section should adopt linear function And the power function. The maximum wind speed in the mid-canyon wind profile is larger than the maximum wind speed in both sides of the wind profile, and the corresponding wind speed inflection point height is also larger. The wind speed at the same height in the canyon changes in a parabola on the cross section of the canyon, The wind speed reaches the maximum at about 60m on both sides of the mountain; the narrower the canyon, the higher the peaks on both sides, the more obvious the “canyon effect” of the wind field in the canyon; the inflection point height of the wind profile wind speed is inversely proportional to the aspect ratio of the canyon The larger the aspect ratio, the smaller the wind profile inflection point height. The formula can calculate the wind speed at any height within the mountain canyon, which can provide a convenient method for calculating the wind speed of the bridges across the mountain gully.