Wind turbine - atmospheric boundary layer interactions: model experiments and implications on numerical simulations

直径在100米数量级的水平轴风力涡轮机是有史以来建造的最大的旋转机械。与大多数涡轮机械不同的是，它们的正常运行条件受到自然变化性的强烈影响。当风力涡轮机部署在风电场中作为大型阵列时，它们之间以及与大气湍流边界层之间相互作用。为了优化风电场的选址和几何布置，以及量化风电场在不同尺度上对陆地-大气交换的综合影响，大气传输过程的计算机模拟需要尽可能真实地对风力涡轮机进行参数化。智力优势：拟议的研究是对风力涡轮机阵列中的流动和能量学进行风洞实验研究，并对数据进行多尺度分析，专门解决计算机建模和参数化问题。人们已经对风力涡轮机叶片的空气动力学有了很多了解，但对风力涡轮机与湍流、高度可变的环境之间的相互作用进行建模的知识还远远不够发达。拟议的研究将使用新一代流体动力学仪器来解决这一差距，与以前的工作相比，分辨率大大提高，并结合新的数据分析技术。立体粒子图像测速仪将用于测量中性层结条件下风洞模型的高分辨率速度图。这些数据将用于解决以下问题：(I)模型参数(如阻力或功率系数、有效粗糙度高度等)，包括它们对流动特性和阵列几何形状的依赖。(2)相干周期结构在螺旋尾迹中的作用，特别强调它们对应力的影响。借用为多级透平机械开发的概念，这些数据将用于测量“确定性应力”。这些压力的相对重要性将被量化，并提出可能的模型。(3)将通过相似方法研究平均速度和应力分布的标度行为。(4)将利用在大涡模拟和次网格尺度建模的背景下新开发的分析工具，审查各尺度上的能量通量。结果将被浓缩成有用的参数和模型，可用于大气中风力涡轮机阵列的微观、中观和全球尺度的模拟。更广泛的影响：拟议的研究将有助于提高从大气环境中提取风能的适用性、效率和长期可持续性的理解。在更广泛的智力影响方面，对大型人造机械、相干流动结构和随机湍流背景之间相互作用的拟议研究可能会导致新的“空间-尺度-时间”建模概念和分析工具。在外展方面，将与现有的由美国国家科学基金会资助的研究生教育和教授联盟(AGEP)计划形成协同效应。目前，纽约-波多黎各中心研究生教育联盟(CNY-PR)和RPI教授的参与重点是为学术生涯招募和指导少数族裔学生。波多黎各的卡瓜斯计划再建一个中心--“国际能源与可持续发展中心”。拟议的研究将使JHU、RPI、这个规划中的中心以及AGEP合作伙伴图拉博大学和波多黎各大学-马亚圭斯大学之间产生有益的协同作用。还计划招聘波多黎各本科生在暑期实习期间参与该项目，并指导博士后学者从事能源和可持续发展领域的学术工作。

With diameters on the order of 100 meters, horizontal axis wind-turbines are the largest rotating machines ever built. Unlike most turbomachines, their normal operating conditions are strongly influenced by natural variability. When deployed as large arrays in wind farms, wind turbines interact among themselves and with the atmospheric turbulent boundary layer. To optimize their siting and geometric arrangements, as well as to quantify the aggregate effects of wind-farms on the land-atmosphere exchanges at various scales, computer modeling of the atmospheric transport processes requires parameterizing the wind turbines as realistically as possible. Intellectual Merit: The proposed research is a wind-tunnel experimental study of flow and energetics in wind-turbine arrays, and multi-scale analysis of data motivated specifically to address computer modeling and parameterization issues. Much is already known about wind-turbine blade aerodynamics, but the knowledge on modeling the interactions of wind-turbines with the turbulent, highly variable environment is far less developed. The proposed research will address this gap using new-generation fluid dynamics instrumentation at a much increased resolution compared to prior work, coupled with new data analysis techniques. Stereo Particle-Image-Velocimetry will be used to measure high-resolution velocity maps in wind-tunnel models of wind-turbine arrays under neutral stratification. The data will be used address the following issues: (i) Model parameters (such as drag or power coefficients, effective roughness height, etc..), including their dependence on properties of the flow and array geometry. (ii) The role of coherent periodic structures in helical wakes, with specific emphasis on their impact on stresses. Borrowing from concepts developed for multi-stage turbomachinery, the data will be used to measure the "deterministic stresses". The relative importance of such stresses will be quantified and possible models proposed. (iii) The scaling behavior of mean velocity and stress profiles will be examined via a similarity approach. (iv) Energy fluxes across scales will be examined, using analysis tools newly developed in the context of Large Eddy Simulation and subgrid-scale modeling. Results will be condensed into useful parameterizations and models that may be used in micro, meso, and global scale simulations of wind-turbine arrays in the atmosphere. Broader impacts: The proposed research will contribute to advance the applicability, efficiency, and understanding of the long-term sustainability of wind energy extraction from the atmospheric environment. In terms of intellectual broader impacts, the proposed research on the interactions among large human-made machinery, coherent flow structures, and a random turbulent background may lead to new 'space-scale-time' modeling concepts and analysis tools. In terms of outreach, synergies with an existing NSF-funded Alliance for Graduate Education and Professoriate (AGEP) program will be developed. Current involvement in the Central New York-Puerto Rico (CNY-PR) Alliance for Graduate Education and the Professoriate at RPI focuses on recruiting and mentoring minority students for academic careers. An additional center is planned for Caguas, Puerto Rico - "The International Center on Energy and Sustainability". The proposed research will enable useful synergies between JHU, RPI, this planned Center, and AGEP partners University of Turabo and University of Puerto Rico-Mayaguez. Recruitment of undergraduate students from Puerto Rico to work during summer internships on this project is also planned, as well as mentorship of postdoctoral scholars for academic careers in the field of energy and sustainability.