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一份报告，加拿大河流的河流水动力能潜力估计为~340GW。为了获取这种能量，已经开发和测试了各种规模的涡轮机系统。这些设备要么独立运行，要么以阵列形式运行，并表现出许多经济、技术和环境影响挑战。此外，大多数河流的流速通常低于1m/S，这不适合转轮水轮机的高效运行。一种新的基于低速流动的流动诱导振动(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。这项建议探讨了FIV作为一种新能源的潜力，在这种能源中，水动力河流能量可以作为负担得起的环境友好解决方案的一部分来利用，以满足日益增长的能源需求。流固耦合(FSI)是工程中常见的现象，它是由细长结构的尾部形成的交替涡以连贯而多变的流态向下游散布而成。这些旋涡在物体上产生涡激作用力，这种作用力是周期性的，由流动诱导振动(FIV)现象引起。在大多数实际应用中，涡系的形成导致了流体力学问题，包括涡激振动(VIV)，通常是孤立圆柱的涡激振动(VIV)，多个圆柱的尾迹诱发振动(WIV)，以及复杂圆柱(如带有附件和狭缝的圆柱)的舞动。研究人员主要研究了抑制FIV以避免过度振动导致故障。相反，在能量采集系统的设计中，必须最大化由于FIV而产生的振动能量，以提高能量转换效率。提出了一种新的实验和数值研究方案，以更好地了解高度耦合的流体-结构系统的基本流动物理，其中各种流动条件和结构属性可以显著改变FIV响应。该方案侧重于研究定常和非定常流动条件下单个和多个振动(柔性)体的流固耦合问题。来自振动响应、连贯结构和尾流动力学的信息将使开发工程师必须解决的最佳流动策略成为可能。这项提案的短期目标中确定的流动情况更为复杂，因为它们调查非圆柱体和多体阵列结构的流动，包括流入和自由表面(浅波和振荡波流动)的影响，以研究能量交换的可行性。这些方面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，以弥合实验流体力学和计算流体力学之间的差距。

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.