Collaborative Research: Large-scale kinetic energy entrainment in the wind turbine array boundary layer - understanding and affecting basic flow physics

1133800 Pi Meneveau/1133993 Pi Castilo本项目的目标是开发和应用实验和计算工具，通过特别关注对大型风力涡轮机阵列具有重要意义的大尺度湍流和垂直动能通量来预测和改进风力发电场的性能。近年来，在假设涡轮机前面的流量给定的情况下，人们投入了大量的精力来提高单个风力涡轮机的效率。此外，了解尾迹如何影响下游涡轮机的性能并对多个此类尾迹的叠加进行建模也受到了相当大的关注；然而，对于大量风力机如何在更大尺度上与风力机阵列边界层(WTABL)中的湍流大气边界层相互作用的基本了解相对较少。最近的研究表明，大型风电场的一个重要性能限制因素是动能从风力涡轮机上方的高空流动进入阵列的速度。无论单个风力涡轮机的效率有多高，或者它对上游风力涡轮机的适应能力有多好，最终是进入整个阵列的垂直动能通量在很大程度上决定了能从大气流动中提取多少电力。本项目涉及的问题旨在更好地了解不同尺度的湍流对垂直卷吸过程的限制因素和影响。所得到的模型应该指导风力涡轮机的放置策略和可能的流动修改，以便可以增加垂直卷吸速率。具体地说，将采用风洞实验和大涡模拟(LES)相结合的方法来解决以下研究问题：(A)正在开发的WTABL和完全开发的WTABL之间的本质区别是什么？(B)流向大尺度相干涡旋对动能垂直卷吸的相对贡献是多少？(C)阵列中不同风力涡轮机之间轮毂高度、速度和功率输出的时空相关性是什么？(D)阵列中的风力涡轮机是否有增加平均卷吸的特殊布置？以及(E)是否可以通过改装旋翼来增加这种卷吸作用来影响大尺度的流动结构？解决这些问题需要在风洞实验和计算机模拟中可以提供的高度受控和可重现的条件下进行实验的能力。这些数据将与一个大型风电场的相关新现场数据进行比较。更广泛的影响：风能的强劲增长意味着美国和世界的大部分陆地和近海表面最终可能被用于大型风力发电场。预测和更好地了解在这种条件下耦合修改后的地表和大气的物理过程是一个及时和关键的研究领域。通过项目活动，PI将帮助培训下一代工程师和科学家，掌握必要的工具和洞察力，帮助实现美国到2030年风能占20%的目标。研究生教育/辅导将强调风洞实验、计算机模拟和现场数据分析之间的相互作用。国际经验(瑞士、西班牙)和工业经验(通用电气)也将在该项目中得到重视。招聘和外展将利用两个PI通过波多黎各联系人(NSF-AGEP和LSAMP)招聘美国拉美裔研究生的持续努力，以及JHU关于复杂系统建模的IGERT。RPI关于能源和环境的GK-12将利用NSF的资源在风能问题上培训教师。PI将继续与巴尔的摩的一所高中进行接触，为高三和高年级学生提供研究经验。

1133800 PI Meneveau/1133993 PI CastilloThe objective of this project is to develop and apply experimental and computational tools for predicting and improving wind farm performance by placing particular attention on large scales of turbulence and vertical fluxes of kinetic energy that are of great significance for large arrays of wind turbines. Much effort has been devoted in recent years to increasing the efficiency of individual wind turbines, assuming a given inflow in front of the turbine. Also, understanding how wakes affect the performance of downstream turbines and modeling superpositions of multiple such wakes has received considerable attention; however, there has been relatively little fundamental understanding of how a large array of wind turbines interacts with the turbulent atmospheric boundary layer at larger scales in the wind turbine array boundary layer (WTABL). Recent research has demonstrated that an important performance-limiting factor for large wind farms is the rate at which kinetic energy can be entrained into the array from the flow aloft, above the wind turbines. No matter how efficient an individual wind turbine is, or how well it can adapt to an upstream wind turbine, ultimately it is the vertical flux of kinetic energy into the overall array that largely determines how much power can be extracted from the atmospheric flow. The questions addressed in this project aim at better understanding the limiting factors and the effects of different scales of turbulence on vertical entrainment processes. The resulting models should guide wind turbine placement strategies and possible flow modifications so that vertical entrainment rates can be increased. Specifically, wind tunnel experiments coupled with large-eddy simulations (LES) will be employed to address the following research questions: (a) What are the essential differences between the developing and the fully developed WTABL? (b) What is the relative contribution from streamwise large-scale coherent vortices to vertical entrainment of kinetic energy? (c) What are the space-time correlations of hub-height velocity and power output between different wind turbines in the array? (d) Are there particular arrangements of wind turbines in the array that increase, on average, the entrainment? and (e) Can large-scale flow structures be affected through rotor modifications to increase such entrainment? Addressing such questions requires the ability to experiment under the highly controlled and reproducible conditions that can be afforded in the wind tunnel experiments and computer simulations. The data will be supplemented with comparisons with relevant new field data from a large wind farm. Broader impacts: The robust growth of wind energy implies the possibility that large portions of the land and near-shore surface of the US and the world may ultimately be used for large wind farms. Predicting and better understanding the physical processes coupling the modified surface and atmosphere under such conditions is a timely and critical area of research. Through project activities the PIs will help train the next generation of engineers and scientists with the necessary tools and insights to help reach the US goal of 20% wind energy by 2030. Graduate education/mentoring will stress the interplay between wind tunnel experimentation, computer simulation and field data analysis. International (Switzerland, Spain) and industrial experiences (General Electric) will also be emphasized in this project. Recruiting and outreach will leverage both PIs' ongoing efforts to recruit US Hispanic graduate students through contacts in Puerto Rico (NSF-AGEP and LSAMP), as well as an IGERT at JHU on modeling complex systems. A GK-12 at RPI on energy and environment will leverage NSF resources in training teachers on wind energy issues. The PI's ongoing outreach to a Baltimore high school will be continued, providing research experiences for high-school juniors and seniors.