Efficient Modeling of Fluid-Structure Interaction in Flapping, Flexible Wings for Real-Time Control and Parametric Design

柔性扑翼是几项发展中技术的重要组成部分，有可能造福于国家基础设施和福利。例如，可以部署带有拍打翅膀的微型机器人车辆来识别密集管道网络中的泄漏、调查空气质量，甚至对农作物进行人工授粉。拍打的翅膀也可以用来收集能量，从而为特定应用的传感器网络提供动力。然而，工程工具还没有充分发展，以利用这些新兴技术的柔性扑翼。目前用于预测扑翼物理特性的方法效率低下，通常需要很长时间才能估计单个扑翼系统的性能。因此，它们不能用于系统必须快速适应动态环境条件的实时控制应用。因此，该奖项的主要目标是开发有效和快速的实验方法来预测控制柔性机翼的物理学。这些方法将推进扑翼技术的设计。该奖项将支持通过蒙大拿州立大学的授权计划招募的美国印第安学生。它还将通过公共宣传活动，包括蒙大拿州家庭科学日和国家生物力学日，促进科学，技术，工程和数学领域。 本计画的主要目的是实现扑翼的降阶流固耦合模型。 传统的流体-结构相互作用模型依赖于耦合的有限元和计算流体动力学求解器，这两者都需要大量的计算资源。 现有的低阶方法通常局限于刚性机翼，不能考虑由弹性结构变形引起的气动力。 通过这项工作开发的模型将提供接近高保真解算器的解算精度，并具有低阶方法所实现的计算效率。 该模型将应用于研究人工翅膀以及真实的昆虫翅膀，并将通过完成以下目标来实现。 首先，机翼的几何形状，结构和空气动力学特性，通过结合微计算机断层扫描，计算流体动力学，实验模态分析，模型更新程序。 其次，将使用一种新的可变形叶片元素动量方法推导出流固耦合框架。 变形机翼空气动力学最近通过一个预先确定的系数和动态修正系数的查找表来计算，这些系数和动态修正系数将在必要时加入准定常模型中。这种低阶模型最初将以直接高保真计算模拟为基准。第三，对模型进行实验验证。一个连杆机构将被用来产生扑翼运动。 将测量机翼应变、气动力和扭矩，并与理论预测进行比较。该项目的预期成果是一个强大的流固耦合框架，能够支持实时控制以及参数化设计的扑动，柔性翼技术。该项目由CBET流体动力学，建立计划，以刺激竞争力的研究（EPSCoR），生物-该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准。

Flexible flapping wings are an important component in several developing technologies with potential to benefit national infrastructure and welfare. For example, miniature robotic vehicles with flapping wings could be deployed to identify leaks in dense networks of pipes, to survey air quality, or even to artificially pollinate crops. Flapping wings could also be used to harvest energy and thus power a sensor network for specific applications. However, engineering tools are not sufficiently evolved to utilize flexible flapping wings for these emerging technologies. Methods currently used to predict the physics of flapping wings are inefficient, often requiring long time to estimate the performance of just a single flapping wing system. As such, they cannot be used for real-time control applications where the system must adapt rapidly to dynamic environmental conditions. The primary goal of this award is therefore to develop efficient and rapid experimental methods to predict the physics governing flapping flexible wings. Such methods will advance the design for flapping wing technologies. This award will support American Indian students recruited through Montana State University's EMPower program. It will also promote science, technology, engineering and math fields through public outreach activities including Montana State Family Science Day and National Biomechanics Day. This project specifically aims to realize a reduced-order fluid-structure interaction model of flapping wings. Conventional fluid-structure interaction models rely on coupled finite element and computational fluid dynamics solvers, both which require considerable computational resources. Existing low-order approaches are typically restricted to rigid wings and cannot account for the aerodynamic forces that result from elastic structural deformation. The model developed through this work will deliver solution accuracy near that of high-fidelity solvers with the computational efficiency achieved by low-order methods. This model will be applied to study both artificial wings as well as real insect wings and will be realized by accomplishing the following objectives. First, wings will be geometrically, structurally, and aerodynamically characterized via a combination of micro-computed-tomography scans, computational fluid dynamics, experimental modal analysis, and model updating routines. Second, the fluid-structure interaction framework will be derived using a novel deformable blade element momentum approach. Deformed wing aerodynamics are accounted for efficiently through a predetermined look-up table of coefficients and dynamic correction factors that will be incorporated into the quasi-steady model as necessary. This low-order model will initially be benchmarked against direct high-fidelity computational simulation. Third, the model will be validated experimentally. A linkage mechanism will be used to generate flapping kinematics. Wing strain, aerodynamic forces and torques will be measured and compared to theoretic predictions. The expected outcome of this project is a robust fluid-structure interaction framework capable of supporting real-time control as well as parametric design of flapping, flexible wing technologies.This project is jointly funded by CBET-Fluid Dynamics, the Established Program to Stimulate Competitive Research (EPSCoR), and BIO-IOS programs.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.