Severe Storm Wave Loads on Offshore Wind Turbine Foundations (SEA-SWALLOWS)

海上风力涡轮机基础上的严重风暴波浪载荷（海燕）

基本信息

批准号：
EP/V050079/1
负责人：
Jun Zang
金额：
$ 101.25万
依托单位：
University of Bath
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2021
资助国家：
英国
起止时间：
2021 至无数据
项目状态：
未结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FV050079%2F1
关键词：
Severe Storm Wave Loads Offshore

项目摘要

Offshore structures, including offshore wind turbine foundations, marine renewable energy device support structures, bridge piers, and floating vessels, are routinely exposed to harsh environmental loads. These frequently drive the design. The physics and statistics of wave-structure interaction are complex and still not fully understood for strongly non-linear loads as experienced in the most severe conditions.The particular focus of this project is fixed offshore wind turbines. These are one of the most promising sources of clean energy; and central to the UK's ambitions to become carbon neutral. The price of offshore wind has fallen significantly over the past ten years. Part of this reduction has been due to improvements in technical understanding leading to less conservative designs. Recently, there has been a trend to move to more exposed and deeper water locations with 'better' wind resources. However, such locations are susceptible to more extreme wave heights and subsequently more severe loading. These changes have increased the importance of wave loading models able to give accurate predictions of base shear and moment time-series. It is important that such models predict not only the magnitude of the load but also the correct frequency content of the loading. For instance, a large slamming load may be of sufficiently short duration that the load is not simply transmitted to the foundation. Further, structures are typically designed so as to avoid the natural frequency of the storm waves. However, if loading was to occur at higher harmonics of the fundamental wave frequencies these may coincide with the structure's natural frequencies, thus greatly increasing their importance for design. For structural fatigue assessment very long time series are required. Therefore, experimental and high-fidelity numerical models are too resource-intensive to be directly useful for practical engineering calculations. A highly efficient yet still sufficiently accurate alternative is required.The physics of wave loading is typically split into non-breaking and breaking loads. These have different magnitudes and timescales as they are dominated by different physical phenomena. For non-breaking waves, traditionally the Morison equation has been widely accepted as the starting point for calculating wave loading on offshore structures by most modern design standards. For slender cylinders in the inertia regime such as the monopiles used for offshore wind, extensions have been made to the Morison model, taking wave kinematics as inputs. Predicting wave kinematics is itself a difficult task, particularly for severe yet random sea-states where both standard regular wave stream function theory and 2nd order random wave theory are imperfect models.Breaking waves are notoriously difficult to model numerically and to measure experimentally due to the violence of the hydrodynamics and scaling issues. Various models have been proposed to simulate the time history of the loading. However, when calculating extreme responses and foundation reactions for dynamically sensitive structures, it is generally sufficient to know the total applied impulse (and where it acts) for impact loads rather than the exact time-history. Estimating the impulse is far more robust, quicker and the physics can more easily be modelled. We aim to revolutionize load calculations on offshore structures using novel fluid mechanics to develop fast reduced-order engineering models. While the focus of this work will be examining the impact of extreme wave loading on offshore wind turbine foundations, the ideas and tools generated will be more broadly applicable. We will develop a computationally fast method and an open source tool to be used by practicing engineers in industry to model long-term cyclic loading, leading to more efficient designs of offshore structures, reducing construction cost whilst preserving function and reliability.

近海结构，包括海上风力涡轮机基础，可再生能源设备支撑结构，桥梁码头和浮动容器，通常会暴露于严重的环境载荷上。这些经常推动设计。波浪结构相互作用的物理和统计数据是复杂的，对于在最严重的条件下经历的强烈非线性载荷仍未完全理解。该项目的特定重点是固定的海上风力涡轮机。这些是清洁能源最有希望的来源之一。这是英国雄心勃勃的中立的核心。在过去的十年中，海上风的价格显着下降。这一减少的部分原因是由于技术理解的改进导致了较不保守的设计。最近，有一种趋势是通过“更好”的风资源转向更曝光和更深的水位。但是，此类位置容易受到更极端的波高度，随后更严重的负载。这些变化提高了波载模型的重要性，能够对基本剪切和时刻序列的准确预测。重要的是，此类模型不仅可以预测负载的大小，还可以预测负载的正确频率内容。例如，较大的猛击负载可能足够短，因此负载不简单地传输到基础上。此外，通常设计结构以避免风暴波的固有频率。但是，如果要在较高的基本波频率的较高谐波下进行负载，则可能与结构的固有频率相吻合，从而大大提高其对设计的重要性。对于结构性疲劳评估，需要很长的时间序列。因此，实验性和高保真数值模型过于资源密集型，无法直接用于实际工程计算。需要一个高效但仍然足够准确的替代方案。波载的物理通常分为非断裂和断裂载荷。这些具有不同的幅度和时间尺度，因为它们由不同的物理现象主导。对于非断裂波，传统上，莫里森方程已被广泛接受为按大多数现代设计标准计算海上结构上的波载的起点。对于惯性状态中的细长圆柱体，例如用于海上风的单孔，已经对莫里森模型进行了扩展，将波浪运动作为输入。预测波动运动本身就是一项艰巨的任务，特别是对于严重但随机的海态，标准的常规波流函数理论和第二阶随机波理论都是不完善的模型。众所周知，由于流体动力学和缩放问题的暴力，众所周知，很难在数值上进行建模，并且在实验上进行了测量。已经提出了各种模型来模拟加载的时间历史。但是，当计算动态敏感结构的极端响应和基础反应时，通常足以知道施加的脉冲（以及它的作用）对撞击负荷而不是确切的时间历史。估计冲动更加稳健，更快，物理可以更容易地建模。我们旨在使用新型流体力学来开发快速减少订购工程模型的海上结构上的负载计算。尽管这项工作的重点将检查极端波载对海上风力涡轮机基础的影响，但生成的想法和工具将更加广泛地适用。我们将开发一种计算快速的方法和一种开源工具，可以由行业中的工程师使用，以建模长期的循环负载，从而更有效地设计了离岸结构的设计，从而降低了施工成本，同时保持了功能和可靠性。