The role of onset turbulence on tidal turbine blade loads
The role of onset turbulence on tidal turbine blade loads
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起始湍流对潮汐涡轮机叶片载荷的作用
DOI：
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发表时间：
2010
期刊：
影响因子：
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通讯作者：
S. Bickerton
中科院分区：
文献类型：
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作者：
I. Milne;Rajnish N. Sharma;R. Flay;S. Bickerton
本文采用基于仿真的方法来研究水平轴潮汐涡轮机叶片载荷对湍流起始流结构的敏感性。纵向湍流强度被证明是所考虑的参数中最主要的参数。对于所分析的两个长度尺度，旋转采样效果相似，但是大幅度疲劳载荷循环的数量受到整体长度尺度的影响。 von Kármán 和 Kaimal 谱模型预测的极端载荷和疲劳载荷相似。考虑到现场的湍流特性，潮汐涡轮机设计人员将对这些发现感兴趣，以评估其涡轮机叶片的长期结构性能。简介 近年来，潮汐流涡轮机行业取得了长足的发展，目前已安装了大型设备。然而，由于对暴露在恶劣运行环境中的叶片等关键部件的长期结构性能缺乏信心，有报告称涡轮机开发商对其设备的过度设计高达 30% [8]。如果潮汐流产业要证明商业可行性，并且涡轮机要优化，就必须减少这种不确定性。对于水平轴潮汐涡轮机，水动力载荷超过重力和惯性力。水动力载荷也高度不稳定，起始流动湍流被认为起着重要作用[9]。由于旋转采样，湍流中的时间和空间不均匀性都会导致载荷谱具有显着的每转一次 (1P) 分量。湍流的性质可能是特定地点的，因此湍流引起的载荷之间存在一定程度的变化。本文旨在强调可变性并证明载荷对一系列湍流特性的敏感性。试图对涡轮机叶片的长期结构性能进行建模的涡轮机开发人员应该会对结果感兴趣。湍流描述符 单点纵向湍流强度是风力和潮汐涡轮机叶片载荷最常见的预测因子之一。它是湍流波动的标准偏差除以平均速度（本文假设仅具有纵向 u 分量），
This paper uses a simulation-based approach to investigate the sensitivity of the blade loads for a horizontal-axis tidal turbine to the structure of the turbulent onset flow. The longitudinal turbulence intensity is shown to be the most dominant parameter of those considered. The rotational sampling effects are similar for the two length-scales analysed, however the number of large amplitude, fatigue loading cycles is influenced by the integral length-scale. The predicted extreme and fatigue loads are similar between the von Kármán and Kaimal spectral models. The findings will be of interest to tidal turbine designers for assessing the long-term structural performance of their turbine blades, given the turbulence characteristics at their site. Introduction In recent years the tidal stream turbine industry has witnessed considerable development, such that full-scale devices are now being installed. However, due to a lack of confidence in the long term structural performance of critical components such as the blades, which are exposed to a harsh operating environment, there are reports of turbine developers over-engineering their devices by up to 30 percent [8]. If the tidal stream industry is to prove commercially viable, and the turbines optimised, this uncertainty must be reduced. For a horizontal-axis tidal turbine, the hydrodynamic loads dominate over the gravitational and inertia forces. The hydrodynamic loads are also highly unsteady, with the onset flow turbulence considered to play a significant role [9]. Both temporal and spatial non-uniformities in the turbulent flow induce a load spectrum with a notable once-per-revolution (1P) component due to rotational sampling. The nature of the turbulence is likely to be site specific and there will therefore be a degree of variability between the turbulence induced loads. This paper aims to highlight the variability and to demonstrate the sensitivity of the loads to a range of turbulence characteristics. The results should be of interest to turbine developers who are attempting to model the long term structural performance of their turbine blades. Turbulence Descriptors The single-point longitudinal turbulence intensity is one of the most common predictors of the blade loads for wind and tidal turbines. It is the standard deviation of the turbulent fluctuations divided by the mean velocity (assumed herein as having only a longitudinal u component),