WAKE MEDIATED COUPLING IN OSCILLATING HYDROFOIL TURBINE ARRAYS

该项目的目标是实现可扩展的无阻尼振动水翼涡轮机阵列，提供比当前水电技术更高的效率、更高的功率输出水平和更广泛的适用性。这项拟议的工作将利用最近发现的独特的尾迹结构相互作用，这种相互作用可以在密集排列的振荡器阵列中增加功率输出和效率。使用可以紧密排列在一起的振荡水翼装置的方法，将在以前被认为太浅或太杂乱而不可行的地点为水电打开新的市场。由于许多人口中心位于海岸线和河流沿线，这种新的清洁能源将具有最低的输电成本和损失。这类设备在偏远村庄或因灾难而流离失所的人的临时避难所等离网地点也可能具有无价的价值。较小规模的应用可以创建流量供电的感应站，不依赖短期和对环境有害的消耗性电池，用于监控关键基础设施等应用。在公用事业电网规模，与风能和太阳能等其他可再生能源相比，由于能源的可预测性，振荡涡轮机水力发电阵列将更方便地集成到电网中。虽然风能和太阳能会因天气变化而受到每日变化和间歇性的影响，但特别是潮汐流量可以提前很好地进行准确预测，从而使公用电网中的各种来源能够容易地得到平衡，从而以经济高效的方式满足需求和生产分配。此外，拟议的教育活动将有助于扩大对工程的参与，并激励儿童学习科学、技术、工程和数学(STEM)。北卡罗来纳州的初中生和初中生将在动手实验室活动中学习流动能量收集和工程设计，研究人员将开发并运行该活动，作为广受欢迎的北卡罗来纳州州立大学夏令营项目的一部分。研究人员还将通过为来自北卡罗来纳州公立大学的未被充分代表的本科生提供机会，在PI和Co-PI的实验室从事有指导的研究活动，从而扩大对研究的参与。与传统的旋转涡轮机不同，传统的涡轮机必须分布广泛才能最有效地运行，我们的初步实验表明，当振荡能量收集设备紧密堆积在一起，并且它们的运动被尾流耦合时，实际上是最有效的。这项工作将确定如何对振荡涡轮机阵列进行建模、控制和优化配置，以利用上游和下游设备的尾迹之间的这些协同作用。目前的风能和水动能研究主要集中在从机械或流体动力学的角度研究单个设备的性能，或从电气的角度研究“智能电网”中电源的相互作用和组合。拟议的工作将利用一种不同的方法，在机械层面上利用和优化设备之间的交互。具体地说，实验和分析研究将：(1)研究控制协同尾流-结构耦合的发生、强度和尺度的参数，以及如何利用它来提高二维水力集能器阵列的性能。研究人员还将(2)定量比较振动涡轮机的主动、被动和混合驱动和控制方法，以及(3)量化水体浅度对单个和集体能量收集器尾流结构形成的影响。

The objective of this project is to enable scalable arrays of damless oscillating hydrofoil turbines that will offer higher efficiencies, higher power output levels, and wider applicability than current hydropower technologies. The proposed work will take advantage of unique, recently uncovered wake-structure interactions that can increase power output and efficiency in densely packed arrays of oscillators. The approach of using oscillating hydrofoil devices that can be closely arranged together will open new markets for hydropower in locations previously considered too shallow or cluttered to be feasible. With many population centers located on coastlines and along rivers, this new source of clean energy would have minimal transmission costs and losses. Such devices could also be invaluable in off-grid sites like remote villages or temporary shelters for people displaced by disasters. Smaller scale applications could create flow-powered sensing stations that do not rely on short-term and environmentally hazardous consumable batteries for applications like monitoring critical infrastructure. At the utility grid scale, when compared to other renewable energy sources like wind and solar power, oscillating turbine hydrokinetic power arrays will offer more convenient integration into the power grid due to the predictable nature of the energy source. While wind and solar power are subject to daily variation and intermittency due to weather changes, tidal flows in particular can be accurately predicted well in advance, allowing the various sources in the utility grid to be readily balanced to cost-effectively meet demand and production allocations. In addition, the proposed education activities will serve to help broaden participation in engineering and inspire children to Science, Technology, Engineering, and Math (STEM) studies. North Carolina middle school and junior high school students will learn about flow energy harvesting and engineering design in a hands-on lab activity the researchers will develop and run as part of the popular NC State University summer camp program. The researchers will also broaden participation in research by providing opportunities for underrepresented undergraduate students from public colleges across North Carolina to engage in mentored research activities in the PI's and Co-PI's labs. Unlike traditional spinning turbines, which must be widely spaced to perform most effectively, our preliminary experiments have shown that oscillating energy harvesting devices actually perform most effectively when they are closely packed together and their motions become coupled by the wake flow. This work will determine how arrays of oscillating turbines can be modeled, controlled, and optimally configured to take advantage of these synergistic interactions between the wakes of upstream and downstream devices. Current wind and hydrokinetic energy research largely focus on the performance of individual devices from a mechanical or fluid dynamics standpoint, or the interaction and combination of power sources in a "smart grid" from an electrical perspective. The work proposed will leverage a different approach that exploits and optimizes interactions between devices at the mechanics level. Specifically, experimental and analytic studies will (1) investigate the parameters that govern the occurrence, strength, and scaling of the synergistic wake-structure coupling and how it can be used to enhance the performance of 2D arrays of hydropower energy harvesters. The researchers will also (2) quantitatively compare active, passive, and hybrid actuation and control approaches for the oscillating turbines, and (3) quantify the influence of the shallowness of the water body on the wake structure formation of individual and collective energy harvesters.