Experimental and numerical modeling of unsteady fluid-structure interactions occurring across various interfaces in environmental flows

根据加拿大自然资源部最近的报告，加拿大河流的河流（水力）能源潜力估计约为340吉瓦。为了收获这种能量，已经开发和测试了各种规模的涡轮机系统。这些设备可以独立运行或以阵列形式运行，并表现出许多经济、技术和环境影响挑战。此外，大多数河流通常以低于1 m/s的速度流动，这不适合于旋转涡轮机的有效操作。基于低速流动的新型流致振动（FIV）能量收集可以补充现有技术，并为小型偏远社区提供更好的灵活性。该提案探讨了FIV作为一种新型能源的潜力，其中水力河流能源可以作为经济实惠和环保解决方案的一部分，以满足不断增长的能源需求。流固耦合是工程中常见的现象，它是由细长结构后体以相干但变化的流型向下游脱落而形成的交替涡引起的。这些涡流在主体上产生周期性的涡流诱导力，这是由流动诱导振动（FIV）现象引起的。在许多实际应用中，涡激振动是由涡的形成引起的，包括孤立圆柱的涡激振动（VIV）、多圆柱的尾流激振（WIV）以及复杂圆柱（如带附件和槽的圆柱）的驰振。研究人员主要研究FIV的抑制，以避免过度振动导致故障。相反，在能量收集系统的设计中，由于FIV的振动能量必须被最大化以增加能量转换效率。提出了一种新的实验和数值研究方案，以更好地了解一个高度耦合的流体-结构系统，其中各种流动条件和结构属性可以大大改变FIV响应的基本流动物理。该提案的重点是研究稳定和非稳定流动条件下的单个和多个振荡（柔性）机构的FSI。来自振动响应、相干结构和尾流动力学的信息将允许开发工程师必须解决的最佳流策略。在本提案的短期目标中确定的流动情况更为复杂，因为它们调查了非圆形圆柱体和多体阵列配置的FIV，包括流入和自由表面（浅水和振荡波流）的影响，以研究能量交换的可行性。这些问题在以往的研究中很少涉及。拟议的研究将探索和促进基于机器学习算法的更有效的建模工具的开发，以弥合实验和计算流体动力学之间的差距。

According to the recent report of Natural Resources Canada, the estimated energy potential of the Canadian rivers for in-stream (hydrokinetic) energy is ~340 GW. To harvest this energy, various scales of turbine systems have been developed and tested. These devices operated either standalone or in arrays and exhibit many economic, technical and environmental impact challenges. Furthermore, most rivers typically flow at a velocity lower than 1 m/s, which is not suitable for the efficient operation of the rotary turbine. A new flow-induced vibration (FIV) energy harvesting based on low-speed flows can complement the existing technologies and offer better flexibility for small, remote communities. This proposal explores the potential of FIV as a novel energy source where the hydrokinetic river energy can be utilized as a part of an affordable and environmentally friendly solution to meet the growing energy demands. Fluid--structure interaction (FSI) is a common phenomenon in engineering caused by the alternating vortices formed in the aft body of the slender structure shed downstream with a coherent but varied flow pattern. These vortices create vortex-induced forces on the body, which are periodic, resulting from the phenomenon of flow -induced vibration (FIV). In most practical applications, vortex formation is responsible for FIV, including vortex-induced vibration (VIV), generally of the isolated cylinder, wake- induced vibration (WIV) of multiple circular cylinders, as well as the galloping for complicated cylinders (such as cylinder with attachments and slots). Researchers have primarily studied the suppression of FIV to avoid excessive vibrations leading to failure. In contrast, in the design of energy harvesting systems, the vibrational energy due to FIV must be maximized to increase energy conversion efficiency. A novel experimental and numerical research program is proposed to better understand the underlying flow physics of a highly coupled fluid-structure system, where a variety of flow conditions and structural attributes can considerably alter the FIV response. The proposal focuses on studying the FSI of single and multiple oscillating (flexible) bodies in steady and unsteady flow conditions. Information from vibration response, coherent structures, and wake dynamics will allow developing optimal flow strategies that are essential for engineers to address. The flow cases identified in the short-term objectives of this proposal are more complex, as they investigate FIVs of non--circular cylinders and multi--body array configurations, including effects of the inflow, and free surface (shallow and oscillatory wave flows) to study the feasibility of energy exchange. These aspects are seldom addressed in previous research. The proposed research will explore and facilitate the development of more effective modeling tools based on machine learning algorithms to bridge the gap between experimental and computational fluid dynamics.