Collaborative Research: A multi-scale approach for optimizing tidal kinetic energy extraction for sustainable power generation

项目负责人：Cowles， Geoffrey / Martinelli， luigi提案编号：1336007 / 1336020机构：马萨诸塞大学，达特茅斯/普林斯顿大学标题：合作研究：优化可持续发电潮汐动能提取的多尺度方法潮汐能转换（TISEC）设施提供了高度可预测和可靠的能源。考虑到向可再生能源迁移的经济和社会动机，人们对这项技术产生了极大的兴趣。然而，目前还不清楚在真实的海洋条件下最有效的设计是什么。第二个悬而未决的问题与环境影响有关。这样的装置能够从水柱中提取出很大一部分能量，并且能够产生对床应力的局部修改，从而在基材可移动的位置产生形态动力学调整。当安装在入口或收缩处时，涡轮阵列可以影响海湾和邻近海洋之间的水交换。准确量化环境影响对场地规划和许可至关重要。目前，研究人员正在研究与潮汐动能提取相关的科学问题，使用各种计算工具，从评估设备性能的商业CFD代码到评估影响和选址的海洋模型。如果单独使用，这些方法被迫依赖于简化的假设，从而降低了计算的准确性和实用性。设备尺度的CFD模型通常采用均匀入流速度，忽略了影响设备性能的实际特定海洋条件，如垂直切变、表面波、自由流湍流和潮汐椭圆偏心。大型水动力模型通常采用亚网格尺度的方法来模拟能量提取，使用简单的参数化来表示装置对流场的影响。本项目将采用多模型方法将感兴趣的尺度联系起来。设备规模的模拟将使用具有最佳形状设计能力的RANS CFD代码进行。形状设计过程采用了一种基于控制理论的高效方法来构建梯度。对于影响评估和选址评估所需的更大尺度，将采用非结构化网格海洋模型。这些模型将使用双向方法进行耦合。装置尺度的模拟将提供动量损失和紊流动能的变化，为海洋模型中能量提取的精确亚网格尺度参数化提供必要条件。海洋模型将为装置尺度模拟提供真实的流动条件。耦合方法将应用于理想和现实领域，并且能够在考虑对环境的潜在影响的同时提高现实条件下的涡轮机性能。该项目将开发和测试一个过程，以优化和评估整个临界尺度范围内的潮汐动能提取。特别是，多模型方法将实现(1)自动装置形状设计，以提高实际流动条件下的效率；(2)使用涡轮效应的精确参数化来评估对循环和泥沙输送的影响。这项研究的一个重要成果将是开发和演示一套工具，以支持潮汐能装置的规划和许可过程。

PI: Cowles, Geoffrey / Martinelli, LuigiProposal Number: 1336007 / 1336020Institution: University of Massachusetts, Dartmouth / Princeton UniversityTitle: Collaborative Research: A multi-scale approach for optimizing tidal kinetic energy extraction for sustainable power generationTidal in-stream energy conversion (TISEC) facilities provide a highly predictable and dependable source of energy. Given the economic and social incentives to migrate towards renewable energy sources there has been tremendous interest in the technology. However, at present it is not yet apparent what the most efficient design would be for real ocean conditions. A second open issue pertains to environmental impact. Such devices are able to extract a significant fraction of energy from the water column and can produce local modifications to the bed stress resulting in a morphodynamic adjustment in locations where the substrate is mobile. When sited in an inlet or constriction, a turbine array can influence the exchanges of water between an embayment and the adjacent ocean. An accurate quantification of environmental impact is critical for site planning and permitting.Presently, researchers are examining scientific issues related to tidal kinetic energy extraction using a variety of computational tools that range from commercial CFD codes for evaluating device performance to ocean models for evaluating impact and site selection. Taken independently, such approaches are forced to rely on simplifying assumptions that decrease the accuracy and utility of the computations. The device scale CFD models typically employ a uniform inflow velocity, ignoring realistic site-specific ocean conditions that influence device performance such as vertical shear, surface waves, free-stream turbulence, and eccentricity of the tidal ellipse. Large-scale hydrodynamic models typically employ subgrid-scale approaches to model energy extraction using simple parameterizations to represent the influence of the device on the flowfield.This project will apply a multi-model approach to link the scales of interest. Device scale simulations will be performed using a RANS CFD code with an optimal shape design capability. The shape design procedure uses a highly efficient approach based on control theory for construction of the gradient. For the larger scales necessary for impact assessment and site evaluation, an unstructured grid ocean model will be employed. The models will be coupled using a two-way approach. The device scale simulations will provide momentum loss and changes in turbulent kinetic energy needed for accurate subgrid-scale parameterization of energy extrac- tion in the ocean model. The ocean model will provide realistic flow conditions for the device scale simulations. The coupled approach will be applied to both idealized and realistic domains and will be capable of improving turbine performance in realistic conditions while simultaneously considering the potential impacts to the environment.This project will develop and test a process for optimizing and evaluating tidal kinetic energy extraction across the entire range of critical scales. In particular, the multi-model approach will enable (1) automatic device shape design for increased efficiency in realistic flow conditions, (2) assessments of impact on circulation and sediment transport using accurate parameterizations of turbine effects. An important outcome of this research will be the development and demonstration of a suite of tools to support the planning and permitting processes for tidal energy installations.