Collaborative Research: Structured Wakes Behind Oscillating Foils: Characterization, Control, and Cooperative Behavior

利用振荡箔的能量收集有潜力开发大量的水动力（潮汐和河流）能源，并为滨水社区提供可再生和可持续的能源。振荡箔对海洋动植物的危害较小，可以在更多的位置和较低的水速下运行，而不是传统的旋转水动力涡轮机。振荡箔也可以彼此靠近放置，增加功率密度-可以从给定区域提取的总功率。然而，优化这种布局取决于对相邻水翼之间相互作用的更好理解，特别是结构尾流形成的方式，顺流而下并影响相邻水翼的性能。该研究项目将解决这些问题，并导致预测工具的发展，可以帮助开发商业上可行的水动能系统，使用实验和计算方法的紧密结合，将开发一个系统框架，用于系统地表征和控制振荡箔之间的尾流相互作用。主要目标是基于扑动运动的运动学对涡旋拓扑和对流路径进行分类。这些工具将在机器学习分类和回归模型的帮助下开发。一旦尾流结构被很好地预测，控制算法将被开发，涡翼相互作用将被描述为有益和有害的相互作用，以达到能量收集的目的。将使用二维直接数值模拟（DNS）和三维大涡模拟（LES）相结合的方法对单个和多个水翼进行模拟。计算机控制的配有力和扭矩传感器的三水翼系统将与使用粒子图像测速（PIV）的非定常尾流速度测量相结合，用于大型开放地表水水槽。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Energy harvesting using oscillating foils has the potential to tap large hydrokinetic (tidal and riverine) energy resources and provide renewable and sustainable energy to water-front communities. Oscillating foils are less harmful to marine flora and fauna, can operate in many more locations and at lower water speeds than is possible for conventional rotary hydrokinetic turbines. Oscillating foils can also be placed in close proximity to each other, increasing the power density - the total power that can be extracted from a given area. However, optimizing this placement depends on improved understanding of the interactions between adjacent hydrofoils, and in particular, the way in which structured wakes form, advect downstream and impact the performance of a neighboring hydrofoil. This research project will address these issues, and lead to the development of predictive tools that can aid in the development of commercially feasible hydrokinetic energy systems, Using a tightly-integrated combination of experimental and computational approaches, a systematic framework will be developed for systematically characterizing and controlling the wake interactions between oscillating foils. The primary goal is to categorize vortex topology & convective paths based on the kinematics of the flapping motion. These tools will be developed with aid of machine learning classification and regression models. Once the wake structure is well-predicted, control algorithms will be developed, and the vortex-foil interactions will be characterized in terms of beneficial and detrimental interactions for the purpose of energy harvesting. Simulations of single and multiple hydrofoils will be performed using a combination of two-dimensional direct numerical simulation (DNS) and three-dimensional Large Eddy Simulations (LES). A computer-controlled three-hydrofoil system each equipped with force and torque sensors will be used in a large open surface water flume in conjunction with unsteady wake velocity surveys using Particle Image Velocimetry (PIV).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.