Investigation of the effects of realistic non-homogenous turbulence on structural loading and the performance of tidal energy devices

不同于风力机所经历的密度较低、速度较高的无界流动中的湍流，结构载荷和潮流发生器的性能更受运行环境中流动的湍流特性的影响。虽然潮汐站点的平均水流特征已被很好地理解，并可以有一定的信心进行模拟，但关于湍流特征的知识相对缺乏。虽然目前正在开发和实施一系列潮流发电机(TSG)，但由于对湍流影响缺乏确定性，对可靠性和性能的预测不够准确，从而阻碍了进展，因此经济上可行，而且通常会导致非常保守的设计方法，而实施起来成本更高。尽管设计谨慎，但湍流已被确定为运行单元中发生的部件故障的可能原因。在过去的几年里，随着几篇论文的发表和几个潜在地点的实地研究最近由Partrac完成--其结果不是公开的--对潜在潮汐流站的湍流的特征得到了越来越多的关注。尽管有这样的关注，但文献中几乎没有专门研究湍流对潮汐蒸汽发生器影响的论文，也没有发现关于在设备横截面上具有空间可变的影响的湍流特征的论文。该项目提案是在与Venugopal博士讨论后形成的，并将与目前正在进行的EPSRC资助的FloWTurb项目相关。潮汐站点的测量数据将被用来开发一个计算模型，并用CFD软件实现，以模拟潮汐渠道流中真实的非均匀湍流。然后，该模型将被用来研究其对潮流发电机结构载荷(特别是疲劳载荷)的影响，并有可能模拟当前正在实施的实际装置和/或部件。然后，模型的复杂性可以扩展到包括波浪载荷，进一步研究对单个单独发电机和阵列性能的影响是可能的。将通过规模实验室测试寻求对结果的实验验证，最好是将FloWave设施与FloWTurb项目结合使用。这项工作的一个组成部分将包括研究在实验装置中调节流动的方法，以可靠和可控的方式紧密匹配所需的湍流特性。这方面的开发工作可以利用工程学院提供的小型水槽进行。该项目的结果最终将被用来提供关于实际潮流场址的湍流特性的更有效的设计建议。

Unlike turbulence in the less dense, higher velocity and unbounded flow experienced by wind turbines, structural loading and the performance of tidal stream generators is more heavily influenced by the turbulent characteristics of flow in the operating environment. Whilst the characteristics of mean flow at tidal sites are well understood and can be modelled with some confidence, there is a comparative lack of knowledge regarding turbulence characteristics. Although a range of tidal stream generators (TSG's) are currently being developed and implemented, this lack of certainty in the effects of turbulence serves to hinder progress through less accurate prediction of reliability and performance, thus economic viability, and generally results in very conservative design approaches which are inherently more expensive to implement. Despite cautious design, turbulence has been identified as a possible cause in component failures that have occurred in operational units. Characterisation of turbulence at potential tidal stream sites has gained increasing focus in the last few years with several papers being published and a field study at several potential sites recently having been completed by Partrac - the results of which are not in the public domain. Despite this focus, few papers specifically investigating the effects of turbulence on tidal steam generators are available in the literature and none have been found regarding the effects turbulence characteristics that are spatially variable over the cross sectional area of the device.This project proposal was formed after discussion with Dr Venugopal and will be associated with the currently ongoing EPSRC funded FloWTurb project. Measurement data from tidal sites will be used to develop a computational model, implemented with CFD software, of realistic non-homogeneous turbulence in tidal channel flow. This model will then be used to investigate its effects on the structural loading (particularly fatigue loading) of tidal stream generators with the possibility to model actual devices and/or components currently being implemented. The complexity of the model may then be extended to include wave loading, with further work investigating effects on performance of both single individual generators and arrays a possibility. Experimental validation of results will be sought via scale laboratory testing, preferably using the FloWave facility in conjunction with the FloWTurb project. A component part of this work will include investigation of methods for conditioning flow in the experimental facility to closely match desired turbulence characteristics in a reliable and controlled fashion. Development work for this can be undertaken using the small flume available within the School of Engineering. The results of the project will ultimately be used to provide recommendations for more effective design with regards to turbulent flow characteristics at actual tidal stream sites.