山区峡谷风场分布特性及地形影响的数值模拟

发布时间：2019-03-13 14:50

【摘要】：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。
[Abstract]:In order to reveal the spatial distribution characteristics of the mountain canyon wind field and the influence of the valley topography on the intra-valley wind field distribution, according to the terrain characteristics of the mountain canyon, the geometric model of the canyon is discretized into the elevation point cloud in AutoCAD. Using the reverse engineering software Imageware, the elevation point cloud is simulated to synthesize the terrain surface of the canyon and then imported into the Gambit to generate the calculation model which meets the requirements. The FLUENT software is used to select the Realizable model suitable for mountain wind field, and the SIMPLE algorithm with good stability is used to simulate the wind field characteristics of the canyon. Finally, according to the terrain characteristics of the canyon and its influence parameters, a formula for calculating the wind speed magnification factor of the canyon is proposed, and a number of examples are used to verify its correctness. The results show that the wind profile of the mountain canyon can be divided into 3 sections, and the power function model commonly used in plain area can not be applied, and the profile of the canyon wind profile has obvious inflection points, and the wind profile of the canyon can be divided into three sections. Linear function and power function should be used to simulate the profile of wind profile in the increase of wind speed. The maximum wind velocity in the middle position of the canyon is greater than that in the two sides, and the height of the corresponding wind velocity inflection point is also larger. The wind speed at the same height observation point in the canyon changes parabola on the cross section of the canyon and reaches the maximum at about 60 m from both sides of the mountain body, and the narrower the canyon, the higher the peak on both sides of the canyon, the more obvious the "canyon effect" of the wind field in the canyon is. The height of wind velocity inflection point of wind section is inversely proportional to the ratio of height to width of canyon. The higher the ratio of height to width of canyon, the smaller the height of wind velocity inflection point of wind section. The formula can be used to calculate the wind speed at any height in mountain canyons and provide a simple method for calculating the reference wind velocity of bridges crossing mountain canyons.
【作者单位】：中南大学土木工程学院;
【基金】：国家自然科学基金项目(51078356)
【分类号】：U442.59

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