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

近年来，政治上越来越多地认识到可再生能源系统的经济和社会效益，这导致这类系统的技术进步步伐加快，在陆地和沿海水域部署可再生能源装置的紧迫性也越来越大。与此同时，人们认识到，为了充分利用可再生发电的机会，有必要了解(并适应)发电设施附近的广泛环境干扰。本项目针对潮流涡轮机(TST)--一种安装在潮汐水域中的装置，通过潮流驱动的一组转子叶片的旋转来发电--审查了这一潜在冲突。众所周知，流经TST支承结构的水流与水轮机转子的旋转相结合，会产生湍动的下游尾迹，其能量足以扰乱水轮机所在海床上泥沙的稳定性，并影响泥沙悬浮。这可能会对海底地形产生重大影响，并对因局部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造成不利后果。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。到目前为止，人们对旋翼湍流尾迹内压力分布的性质以及这些尾流扰乱水中和海底沉积物的机制知之甚少。对于多台潮流水轮机组成阵列的情况，海底沉积物的形状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。由于在预测海床响应方面的这些知识差距，TST项目的开发商目前不得不进行昂贵的环境监测计划，以获得安装设备的环境许可。海洋环境，特别是在那些受强潮流影响的地区，通常受到复杂的泥沙运移动力学的影响。因此，拟议研究的主要目的是开发先进的计算工具，以克服上述知识差距，以便预测潮流、潮流涡轮机和海底沉积物床在波浪和潮汐组合条件下复杂相互作用的后果。这项研究将基于以前的研究计划的结果，如超级第一代和第二代。为了解决上述不确定性，将进行计算和实验室模拟研究(I)调查控制复杂的流-TST-沉积物相互作用的基本过程，以及(Ii)改进实用的预测方法，这些方法不仅可供工程师在全面TST规划和设计中使用，也可供监管机构监测安装TST阵列的环境和生态后果。这项研究将采取系统的、多学科的、以证据为基础的方法，包括分析、物理模型实验和数值模拟部分，以解决和描绘影响海床对沿海水域TST沉积反应的关键过程。

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