CAREER: Hydrodynamics of Adaptive Lifting Surfaces in Unsteady Flows: An Integrated Experimental and Analytical Study

非定常流场在许多水下应用中都很常见，例如在高海况下，在螺旋桨尾流中，在合作游泳或潮汐和波浪期间。在这样的环境中，悬停、站位保持或执行任何其他动态操作对传统的自主水下航行器（auv）来说都变得极其困难，因为它们通常是在固定的操作包线内设计的刚性水翼。然而，水生游泳者可以适当地改变他们的鳍和尾巴来控制所有位置和方向的非定常力。工程师们可以设计出具有仿生变形水翼的高机动性下一代auv，模仿这种性能。但主要的瓶颈是缺乏控制这种变形升力表面流固相互作用的非定常流体动力学知识。因此，本项目的主要目的是深入了解自适应升力表面的非定常流体力学。该项目还将在各级学生中促进海洋流体力学和水下机器人的先进教育，包括在奥兰多科学中心和奥兰治县公共图书馆的推广活动。本提案的目标是发展新的研究和教育范式，揭示和推广变形升力表面的物理特性，以优化其在遇到瞬态尾流流入条件时的性能。提出了一种实验与分析相结合的方法来研究非定常流场中自适应升力面的非线性流固耦合。中心假设是，形状变形可以通过选择性地调整瞬态尾流的水弹性响应来动态平衡这种自适应升力表面上的非定常载荷。具体目标是：(a)揭示水下自适应升力面在一定非定常流场范围内的复杂非线性FSI响应；(b)通过三维流场和地表压力的时间分辨实现，解析涡度动力学和地表压力的时空特征；(c)发现动态变形的升力面受到周期性涡旋扰动引起的空间变化的流入时，上述非线性FSI响应的变化；(d)大力推进现有的以潜在流量为基础的框架，发展分析模型。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。

Unsteady flow fields are common in many underwater applications, such as during high sea conditions, in a propeller wake, during cooperative swimming or during tides, and waves. In such environments, hovering, station keeping, or performing any other dynamic maneuvers become extremely difficult for traditional autonomous underwater vehicles (AUVs) because they are typically designed with rigid hydrofoils within a fixed operational envelope. However, aquatic swimmers can aptly morph their fins and tails to control unsteady forces across all positions and orientations. Engineers can design highly maneuverable next-generation AUVs with bio-inspired morphing hydrofoils which can mimic such performance. But a major bottleneck has been the lack of knowledge of unsteady hydrodynamics that govern the fluid-structure interaction of such morphing lifting surfaces. Therefore, the principal aim of this project is to provide a deep understanding of the unsteady hydrodynamics of adaptive lifting surfaces. This project will also promote advanced education of marine hydrodynamics and underwater robotics amongst students at all level, including outreach activities at the Orlando Science Center and the Orange County Public Library.The goal of this proposal is to develop new research and educational paradigm that will reveal and generalize the physics of morphing lifting surfaces to optimize its performance while encountering transient wake-inflow conditions. An integrated experimental and analytical approach is proposed to study the non-linear fluid-structure interaction (FSI) of adaptive lifting surfaces in such unsteady flows. The central hypothesis is that shape morphing can dynamically balance the unsteady loads on such adaptive lifting surfaces by selectively tuning the hydro-elastic response in a transient wake-inflow. The specific objectives are: (a) Unravel the complex non-linear FSI response of adaptive underwater lifting surfaces in a range of unsteady flows; (b) Decipher the spatial and temporal features of the vorticity dynamics and surface pressure through the time-resolved realization of the 3D flow-field and surface pressure; (c) Discover the changes in the above non-linear FSI response when the dynamically deforming lifting surface is subjected to a spatially varying inflow caused by periodic vortical disturbances; (d) Develop analytical models by significantly advancing the existing potential-flow-based framework.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.