The characterisation of the hydrodynamic loads on tidal turbines due to turbulence
The characterisation of the hydrodynamic loads on tidal turbines due to turbulence
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DOI：
10.1016/j.rser.2015.11.095
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发表时间：
2016-04
影响因子：
15.9
通讯作者：
I. Milne;A. Day;Rajnish N. Sharma;R. Flay
中科院分区：
文献类型：
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作者：
I. Milne;A. Day;Rajnish N. Sharma;R. Flay
为了减轻过早失效、降低过度保守性并最终确保潮汐涡轮机的商业可行性，必须改进由于开始湍流引起的水动力叶片载荷的特性。以前，关注快速流动的潮汐流中的湍流和随后施加到转子上的不稳定载荷的文献非常有限。然而，在潮汐能社区的活动增加，导致了新的调查和见解，这是在这篇paper.It已被发现，通过使用声学多普勒传感器，流向湍流强度一般倾向于在拟议的潮汐能网站的中间深度的值约为6-8%。湍流的各向异性结构和尺度与基于明渠的模型比基于大气的相关性更一致的证据也已被发现。快速畸变理论已被应用于估计，由于涡轮机的存在，在起始自由流中的流向湍流速度波动的标准偏差可能被显著放大15%。在转子的旋转频率下，湍流波动在叶片的外翼展上也被预测保持良好的相关性。最近的模型尺度实验使非定常流体动力学载荷与定常流载荷分离。对于边界层主要附着在叶片上的情况，这使得能够开发线性传递函数，并将其应用于模拟对多频强迫的响应。还发现，与延迟分离和动态失速相一致的现象可导致叶片根部弯矩超过稳定值25%，在设计中需要考虑这一点，以降低故障概率。
An improved characterisation of the hydrodynamic blade loads due to onset turbulence is essential in order to mitigate premature failures, reduce excessive levels of conservativeness and ultimately ensure the commercial viability of tidal turbines. The literature focussing on the turbulence in fast flowing tidal streams and of the unsteady loads that are subsequently imparted to rotors has previously been very limited. However, increased activity in the tidal energy community has led to new investigations and insights which are reported in this paper.It has been found that through the use of acoustic Doppler-based sensors, the streamwise turbulence intensities generally tend to a value of approximately 6–8% at the mid-depth of proposed tidal energy sites. Evidence that the anisotropic structure and scales of the turbulence are more consistent with open-channel-based models than atmospheric-based correlations has also been found. Rapid distortion theory has been applied to estimate that the standard deviation of the streamwise turbulent velocity fluctuations in the onset free-stream flow may be amplified significantly by 15% due to the presence of a turbine. The turbulent fluctuations have also been predicted to remain well correlated over the outer span of the blades at the rotational frequency of the rotor.Recent model-scale experiments have enabled the unsteady hydrodynamic loading to be isolated from the steady-flow loading. For cases where the boundary layer remains primarily attached across the blades, this has enabled linear transfer functions to be developed and applied to model the response to a multi-frequency forcing. It has also been found that phenomena consistent with delayed separation and dynamic stall can result in a blade root bending moment that exceeds the steady value by 25%, and this needs to be taken into account in design to reduce the probability of failure.