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首页> 外文会议>ES2011;International conference on energy sustainability >THE WIND SHEAR EXPONENT: COMPARING MEASURED AGAINST SIMULATED VALUES AND ANALYZING THE PHENOMENA THAT AFFECT THE WIND SHEAR
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THE WIND SHEAR EXPONENT: COMPARING MEASURED AGAINST SIMULATED VALUES AND ANALYZING THE PHENOMENA THAT AFFECT THE WIND SHEAR

机译：风切变指数：比较模拟值的测量值并分析影响风切变的现象

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When assessing a region for wind energy the wind shear is a key factor to consider because of its profound effect on power density as a function of height. Traditionally, wind shear parameters are derived either from local velocity measurements at two or more heights or from surface roughness characteristics to predict the wind speed at hub height for a particular site. However, recent measurements in a complex terrain (non-mountainous) region indicate that the measured wind shear exponent is significantly higher than the value predicted by land use characteristics and modeled results. Virtual wind shear parameters: alpha and z_o, created by the modeled flow fields of the complex terrain of southeastern Ohio's Appalachian foothills are determined with computational fluid dynamics simulations designed for complex terrain. Then the first year's measurements from the extra-tall tower in the region provide a direct evaluation of the wind shear parameters: alpha and z_0. These values, characteristic of the measurements, are compared against values determined from the local land use characteristics as well as those found by modeling with a computational fluid dynamics wind simulator. It has been found that the measured value of the wind shear exponent is larger, by a factor of 2, than the values currently used in published state wind maps. Phenomena affecting wind shear are also analyzed. Diurnal and changes in reference heights have large effects on the measured wind shear. It is demonstrated that for this site an overall annual average value of the wind shear coefficient is an inaccurate representation of the wind shear because of the range of variability that occurs seasonally. It is also shown that extrapolating from near-surface measurements to hub heights can yield inaccurate predictions of wind speed and, more importantly, wind power.
机译：在评估风能区域时，风切变是要考虑的关键因素，因为风切变对功率密度随高度的影响很深。传统上，风切变参数是从两个或多个高度的局部速度测量值或表面粗糙度特性中得出的，以预测特定站点在轮毂高度处的风速。但是，最近在复杂地形（非山区）区域进行的测量表明，测得的风切变指数显着高于土地利用特征和模型结果所预测的值。通过为复杂地形设计的计算流体动力学模拟，确定了由俄亥俄东南部阿巴拉契亚山麓丘陵复杂地形的模拟流场创建的虚拟风切变参数：α和z_o。然后，从该地区超高塔的第一年的测量值可以直接评估风切变参数：alpha和z_0。将这些值（测量的特征）与从本地土地使用特征以及通过使用计算流体动力学风模拟器进行建模得出的值确定的值进行比较。已经发现，风切变指数的测量值比当前发布的状态风图中使用的值大2倍。还分析了影响风切变的现象。日高和参考高度的变化对测得的风切变影响很大。结果表明，由于季节性变化的范围，该站点的年平均风切变系数平均值不能准确表示风切变系数。还表明，从近地表测量值推断到轮毂高度可能会得出不准确的风速预测，更重要的是风能预测。

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