Performance and near-wake characterization of a tidal current turbine in elevated levels of free stream turbulence
Performance and near-wake characterization of a tidal current turbine in elevated levels of free stream turbulence
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DOI：
10.1016/j.apenergy.2019.113639
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发表时间：
2019-07
期刊：
影响因子：
11.2
通讯作者：
A. Vinod;A. Banerjee
中科院分区：
文献类型：
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作者：
A. Vinod;A. Banerjee
潮汐涡轮机部署在自由流湍流（FST）水平较高的地点。从设计的角度来看，考虑FST的升高对其操作至关重要。介绍了一种潮汐涡轮机模型在高FST环境下的动态近尾迹的详细实验测量；利用本课题组研制的有源网格湍流发生器在高架FST中进行灌浆，并评估湍流强度（Ti）和入流积分长度尺度(L)对涡轮近尾迹的影响。试验了三种入流工况：ti ~ 2.2%的准层流和两种ti升高（~ 12-14%）的入流工况，一种为l ~ 0.4D（比涡轮直径大），另一种为el ~D。在准层流中，升高的情况下转子转矩的标准差增加了4.5倍。能量回收也被发现加快了；atX/D= 4时，入流能回收率为37%，是准层流中相应值的两倍。观察到FST升高会破坏尾迹的旋转特性；旋流数下降幅度在12% （x /D= 0.5）和71% （x /D= 4）之间。升高的tif也导致了比准层流情况下大得多的l0 - 2倍。入流积分长度尺度的增加（从0.4DtoD）导致尾流i、尾流结构和各向异性的增强；然而，对尾流恢复速度没有明显的影响。
Tidal turbines are deployed in sites which have elevated levels of free stream turbulence (FST). Accounting for elevated FST on their operation become vital from a design standpoint. Detailed experimental measurements of the dynamic near-wake of a tidal turbine model in elevated FST environments is presented; an active grid turbulence generator developed by our group was used to seed in the elevated FST and evaluate the influence of turbulence intensity (Ti) and inflow integral length scale (L) on the near-wake of the turbine. Three inflow conditions are tested: a quasi-laminar flow withTi~ 2.2% and two elevatedTi(~12–14%) cases, one withL~ 0.4D(Dis the turbine diameter) and the other whereL~D. ElevatedTicases were found to increase the standard deviation of rotor torque by 4.5 times the value in quasi-laminar flow. Energy recovery was also found to be accelerated; atX/D= 4, the percentage of inflow energy recovered was 37% and was twice the corresponding value in quasi-laminar flow. Elevated FST was observed to disrupt the rotational character of the wake; the drop in swirl number ranged between 12% atX/D= 0.5 and 71% atX/D= 4. ElevatedTialso resulted inLthat were considerably larger (>2 times) than the quasi-laminar flow case. An increase in inflow integral length scale (from 0.4DtoD) was observed to result in enhanced wakeTi, wake structures and anisotropy; however, no noticeable influence was found on the rate of wake recovery.