Interactions of flow, tidal stream turbines and local sediment bed under combined waves and tidal conditions (INSTRON)

近年来，对可再生能源系统的经济和社会效益的政治认识日益增强，导致了这种系统的技术进步步伐加快，并增加了在陆地和沿海水域部署可再生能源设备的紧迫性。与此同时，人们已经意识到，为了充分利用可再生能源发电的机会，有必要意识到（并适应）发电装置本身附近的各种环境干扰。目前的项目以潮汐流涡轮机（TST）为例，研究了这种潜在的冲突。潮汐流涡轮机是一种安装在潮汐水中的装置，通过潮汐流驱动一组转子叶片的旋转来发电。已知流经TST支撑结构的水流结合涡轮转子的旋转会在下游产生紊流尾迹，其能量足以扰乱涡轮机所在海床沉积物的稳定性，影响沉积物悬浮。这可能会对海底地形产生重大影响，并对因地貌变化和水中悬浮沉积物变化而流离失所的本土海洋动植物产生不利后果。因此，环境和生态机构、渔业当局和在经济上依赖受影响地区的当地社区往往对大规模实施TST装置表示严重关切。迄今为止，人们对旋翼湍流尾流内压力分布的性质以及这些尾流扰动水中和海底沉积物的机制知之甚少。在若干潮汐流涡轮机以阵列方式建造的情况下，海床沉积物的结构受到每个组成装置产生的复杂压力分布的影响，海底沉积物响应的预测更加不确定。由于在预测海床反应方面存在这些知识缺口，TST项目的开发商目前必须执行昂贵的环境监测计划，以便获得设备安装的环境许可。海洋环境，特别是在受强潮流影响的地区，通常受到复杂的沉积物输送动力学的影响。因此，该研究的主要目的是开发先进的计算工具来克服上述知识空白，以便预测波浪和潮汐联合条件下潮汐流、潮汐流涡轮机和海底沉积物床之间复杂相互作用的后果。这项研究将以以前的研究项目，如Supergen I和II的成果为基础。为了解决上述不确定性，将进行计算和实验室建模研究(i)调查控制复杂流动-TST-沉积物相互作用的基本过程；（ii）改进实用的预测方法，不仅可以用于工程师的全面TST规划和设计，还可以用于监管机构监测安装TST阵列的环境和生态后果。该研究将采用系统的、多学科的、基于证据的方法，包括分析、物理模型实验和数值模拟组件，以解决和描绘影响沿海水域对TST位置的海床响应的关键过程

The increased political recognition in recent years of the economic and societal benefits of renewable energy systems has led to an increased pace of technological advances in such systems and an increased urgency to deploy renewable energy devices on land and in coastal waters. At the same time, there has been a realisation that, in order to exploit fully the opportunities for renewable power generation, it is necessary to be aware of (and to adjust to) a wide range of environmental disturbances in the vicinity of the power generation installations themselves. The present project examines this potential conflict for the case of a tidal stream turbine (TST) - a device installed in tidal waters to generate power by the rotation of a set of rotor blades driven by the tidal current. It is known that flow passing TST support structure combined with the rotation of the turbine rotors produces a turbulent downstream wake that can be sufficiently energetic to disturb the stability of the sediments on the sea bed on which the turbine is constructed and affect the sediment suspension. This may have significant impact on the sea floor topography and adverse consequences for the indigenous marine flora and fauna displaced by the geomorphologiocal changes and changes of suspended sediment in water. As a result, large-scale implementation of TST devices is often viewed with serious concern by environmental and ecological agencies, the fisheries authorities and local communities dependent economically on the affected zones. Thus far, little is known about the nature of the pressure distributions within the turbulent wakes of the rotors and the mechanisms by which these wake flows perturb the sediments in water and on the seabed. For cases in which several tidal stream turbines are constructed in an array, the configuration of the sea bed sediments is subjected to complex pressure distributions arising from from each of the constituent installations and the prediction of sea floor sediment response is even more uncertain. Because of these knowledge gaps in predicting the sea bed response, developers of TST projects have presently to carry out costly environmental monitoring programs in order to obtain environmental permission for installation of devices. The marine environment, especially in those areas that are subject to strong tidal currents, is usually subject to complex sediment transport dynamics. The main aim of the proposed research is, therefore, to develop advanced computational tools to overcome the above knowledge gaps, in order to predict the consequences of complex interactions between tidal flow, tidal stream turbines and the sea floor sediment bed under combined waves and tidal conditions. The research will build upon results from previous research programmes such as Supergen I and II. To tackle the above uncertainties, computational and laboratory modelling studies will be carried out (i) to investigate the fundamental processes controlling the complex flow-TST-sediment interactions and (ii) to improve practical prediction methods that can be used not only by engineers in full-scale TST planning and design but also by regulatory authorities monitoring environmental and ecological consequences of installing TST arrays. The research will take a systematic, multidisciplinary, evidence-based approach involving analysis, physical model experiments and numerical modelling components to address and delineate the key processes affecting the sea bed response to TST placements in coastal waters