Characterization of flow recirculation zones at the Perdigao site using multi-lidar measurements
Characterization of flow recirculation zones at the Perdigao site using multi-lidar measurements
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DOI：
10.5194/acp-19-2713-2019
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发表时间：
2019-03-01
影响因子：
6.3
通讯作者：
Lundquist, Julie K.
中科院分区：
文献类型：
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作者：
Menke, Robert;Vasiljevic, Nikola;Lundquist, Julie K.
由于流动再循环会产生大量的湍流，它会影响风能项目的成功。本研究使用独特的多普勒激光雷达观测来量化山脊背风侧的流动再循环的发生。在为期3个月的Perdigao 2017现场活动中，可以获得复杂地形上流动的广泛观测数据集。选择该战役地点是因为两个几乎平行的山脊的独特地形特征，山谷到山脊顶部的高度差约为200米，山脊到山脊的距离为1.4公里。6台扫描多普勒激光雷达利用距离-高度指示扫描在与脊线正交的几个垂直平面上探测流场。通过这种激光雷达装置，我们实现了沿两个平行脊的三个位置的再循环区域的垂直扫描。我们构建了一种方法来识别扫描中的流动再循环区域，并定义了这些区域的特征。根据我们的数据分析，当风向垂直于脊线方向时，回流风速大于0.5 m s（-1）的时间超过50%。大气稳定性、风速等大气条件影响气流再循环的发生。气流再循环在风速大于8 m s（-1）时更为频繁。河谷内再环流对顺风脊涡轮高度平均风场和湍流场的影响程度对风资源评价具有重要意义。
Because flow recirculation can generate significant amounts of turbulence, it can impact the success of wind energy projects. This study uses unique Doppler lidar observations to quantify occurrences of flow recirculation on lee sides of ridges. An extensive dataset of observations of flow over complex terrain is available from the Perdigao 2017 field campaign over a period of 3 months. The campaign site was selected because of the unique terrain feature of two nearly parallel ridges with a valley-to-ridge-top height difference of about 200m and a ridge-to-ridge distance of 1.4 km.Six scanning Doppler lidars probed the flow field in several vertical planes orthogonal to the ridges using range-height indicator scans. With this lidar setup, we achieved vertical scans of the recirculation zone at three positions along two parallel ridges. We construct a method to identify flow recirculation zones in the scans, as well as define characteristics of these zones. According to our data analysis, flow recirculation, with reverse flow wind speeds greater than 0.5 m s(-1), occurs over 50% of the time when the wind direction is perpendicular to the direction of the ridges. Atmospheric conditions, such as atmospheric stability and wind speed, affect the occurrence of flow recirculation. Flow recirculation occurs more frequently during periods with wind speeds above 8 m s(-1). Recirculation within the valley affects the mean wind and turbulence fields at turbine heights on the downwind ridge in magnitudes significant for wind resource assessment.