The Buhl correction factor applied to high induction conditions for tidal stream turbines
The Buhl correction factor applied to high induction conditions for tidal stream turbines
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DOI：
10.1016/j.renene.2013.05.018
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发表时间：
2013-12
期刊：
影响因子：
8.7
通讯作者：
J. Chapman;I. Masters;M. Togneri;J. A. Orme
中科院分区：
文献类型：
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作者：
J. Chapman;I. Masters;M. Togneri;J. A. Orme
叶片单元动量理论(BEMT)是计算潮汐涡轮机(TST)海洋发电性能的一种有效方法。这种效率是通过做出几个简化的假设来实现的；这些假设的意外结果是省略了一些可能显著改变TST的性能和负载的现象。我们可以通过在BEMT模型中加入适当的修正来改善这一点，这使得我们能够解释这些现象的一些影响。本文研究了在已建立的BEMT求解器中如何对两种现象进行修正：叶尖/轮毂损失和高感度条件。叶尖损失是由于流体绕叶片末端的流动，这是经典的涡轮BEMT处理中忽略的流动特征。在高于装置设计工作范围的高速比下，基于轴向干涉系数a的理论与实验结果相背离，实际上在物理上是站不住脚的。Buhl提出了一个适用于在空气中运行的风力涡轮机的高感应修正系数，并对在水中运行的TST实施了其修正版本。尖端/轮毂损失和高感应度修正相互结合得很好。高感应修正的有效性与实验结果进行了对比；我们发现，与实验室观测相比，我们的模型很好地预测了功率输出，但高估了轴向推力。
Blade Element Momentum Theory (BEMT) is a computationally efficient method of calculating the performance of a tidal stream turbine (TST) generating energy from the ocean. This efficiency is achieved by making several simplifying assumptions; an unintended consequence of these assumptions is the omission of some phenomena that can significantly alter the performance and loads of a TST. We can ameliorate this by incorporating suitable corrections into a BEMT model, which allow us to account for some of the effects of these phenomena. This paper examines the implementation of corrections in an established BEMT solver for two such phenomena: tip/hub losses and high induction conditions.Tip losses are attributable to the flow of fluid around end of the blade, a flow feature omitted in the classical BEMT treatment of turbines. At high tip speed ratios, above the designed operating range of the device, the theory based on an axial interference factor,a, diverges from experimental results and, indeed, becomes physically untenable. Buhl proposed a high induction correction factor for wind turbines operating in air and a modified version of his correction is implemented here for a TST operating in water. The tip/hub loss and high-induction corrections are well-integrated with one another. The validity of the high-induction correction is checked against experimental results; we find that our model predicts power output well but overpredicts axial thrust compared to laboratory observations.