Flow Adjustment Inside and Around Large Finite-Size Wind Farms
Flow Adjustment Inside and Around Large Finite-Size Wind Farms
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大型有限尺寸风电场内部和周围的流量调节
DOI：
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发表时间：
2017
期刊：
影响因子：
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通讯作者：
F. Porté
中科院分区：
文献类型：
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作者：
K. Wu;F. Porté
在这项研究中，大涡模拟进行调查内部和周围的大型有限大小的风力发电场在传统的中性大气边界层的流动。特别强调的是放在表征不同的农场诱导流区域，包括诱导，入口和发展，充分发展，出口和农场尾流区域。风力发电场在流向方向上延伸20公里，包括36个排列成一直线和交错配置的风力涡轮机排。结果表明，在弱的自由大气层结（Γ = 1 K/km）下，即使风电场长度比边界层高度大两个数量级，两个风电场内部和上方的气流以及涡轮机功率也不会达到完全发展状态。在这种情况下，受气流阻塞影响的风电场感应区逆风延伸约0.8 km，并导致对齐和交错布局的第一排涡轮机的功率分别降低1.3%和3%。对于两个风电场布局来说，风电场尾流导致枢纽高度在顺风距离10公里处出现约3.5%的速度赤字。在较强的层结（r = 5 K/km）下，风电场在其入口和出口区域引起的亚临界流的垂直偏转触发重力驻波，其影响逆风传播。他们，反过来，诱导一个大的减速诱导区迎风农场前缘，和一个加速出口区迎风后缘，都延伸约7公里。结果，涡轮机在入口区域的功率输出相对于弱分层的情况降低超过35%。随着气流的调整，它在顺风方向上增加，只有在距农场边缘约8.5 km的交错布局中才能达到充分发展的状态。出口区域的气流加速导致涡轮机功率随该区域顺风距离的增加而增加，并且农场尾流恢复相对较快（与弱分层情况相比），在顺风距离为5 km时达到其流入轮毂高度速度。
In this study, large-eddy simulations are performed to investigate the flow inside and around large finite-size wind farms in conventionally-neutral atmospheric boundary layers. Special emphasis is placed on characterizing the different farm-induced flow regions, including the induction, entrance and development, fully-developed, exit and farm wake regions. The wind farms extend 20 km in the streamwise direction and comprise 36 wind turbine rows arranged in aligned and staggered configurations. Results show that, under weak free-atmosphere stratification ( Γ = 1 K/km), the flow inside and above both wind farms, and thus the turbine power, do not reach the fully-developed regime even though the farm length is two orders of magnitude larger than the boundary layer height. In that case, the wind farm induction region, affected by flow blockage, extends upwind about 0.8 km and leads to a power reduction of 1.3% and 3% at the first row of turbines for the aligned and staggered layouts, respectively. The wind farm wake leads to velocity deficits at hub height of around 3.5% at a downwind distance of 10 km for both farm layouts. Under stronger stratification ( Γ = 5 K/km), the vertical deflection of the subcritical flow induced by the wind farm at its entrance and exit regions triggers standing gravity waves whose effects propagate upwind. They, in turn, induce a large decelerating induction region upwind of the farm leading edge, and an accelerating exit region upwind of the trailing edge, both extending about 7 km. As a result, the turbine power output in the entrance region decreases more than 35% with respect to the weakly stratified case. It increases downwind as the flow adjusts, reaching the fully-developed regime only for the staggered layout at a distance of about 8.5 km from the farm edge. The flow acceleration in the exit region leads to an increase of the turbine power with downwind distance in that region, and a relatively fast (compared with the weakly stratified case) recovery of the farm wake, which attains its inflow hub height speed at a downwind distance of 5 km.