A Comprehensive Investigation of Nonlinear Shock-Induced Flutter in High-Speed Flows

高速流动非常复杂，涉及激波边界层加热、熵层、梯度和粘性相互作用等现象。这些系统中复杂的流体-热-结构相互作用响应对确保高速流动应用的安全性和效率提出了挑战。在高速流动应用中，温度变化和冲击动力学的存在会导致流体-结构相互作用的响应模式，这种模式依赖于力历史，与其他类似系统有很大不同。这个联合计算和实验项目旨在深入了解高速流动中控制流固耦合的关键因素，并识别由于冲击与加热柔性表面之间相互作用而产生的新的非线性动力响应模式。该项目将包括重要的教育和推广活动，包括与当地社区开展不同群体的本科研究项目和K-12推广项目。该项目旨在通过研究一类涉及转换冲击和热梯度的新型场景来填补目前在理解流体-热-结构相互作用方面的空白。目前，我们的理解主要局限于小长度尺度的流动变化明显短于界面长度的情况。该项目通过探索激波在特定速度下的转换如何诱导新的气动弹性颤振模式，并确定温度梯度对这些新响应模式出现的影响，填补了我们知识上的空白。该项目将通过严格的实验和计算研究来实现这些目标，重点关注三个具体任务：（一）利用浸入式边界方法开发和验证计算模型，以全面研究流体-热-结构相互作用；（二）确定在固定和移动激波情况下，热条件对激波边界层与柔性表面相互作用的作用；（三）通过制定基于能量和基于动量的理论分析方法，揭示复杂的物理现象。通过该项目获得的知识将使具有强冲击和热相互作用的更可靠的高速应用的开发和设计成为可能。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。

High-speed flows are highly complex, involving phenomena like shock-boundary layer heating, entropy layer, gradients, and viscous interactions. The intricate fluid-thermal-structural interaction responses in these systems pose challenges toward ensuring safety and efficiency in high-speed flow applications. The presence of temperature changes and shock dynamics in high-speed flow applications can result in fluid-structural interaction response modes which are dependent on the force history and differ significantly from other similar systems. This joint computational and experimental project aims to provide a deep understanding of the key factors governing the fluid-structure interaction at high-speed flows and identify new nonlinear dynamic response modes due to interaction between the shocks and a heated flexible surface. The project will include significant educational and outreach activities, including engaging a diverse group of undergraduate research programs and K-12 outreach program with the local community.The project aims to fill the current gap in understanding fluid-thermal-structural interaction by investigating a novel class of scenarios involving translating shock and thermal gradients. Currently, our understanding is mainly limited to situations where the changes in the flow at small length scales significantly shorter than the interface length. This project fills the gap in our knowledge by exploring how shock wave translation at specific velocities can induce new modes of aeroelastic flutter and determine the influence of temperature gradients on the emergence of these new response modes. The project will accomplish these objectives through rigorous experimental and computational research, focusing on three specific tasks: (i) Developing and validating a computational model using an immersed boundary approach for a comprehensive study of fluid-thermal-structure interaction, (ii) Identifying the role of thermal conditions on shock boundary layer interaction with a flexible surface in both fixed and moving shock situations, and (iii) Unraveling the complex physics through the formulation of theoretical energy-based and momentum-based analysis approaches. The knowledge gained through this project will enable the development and design of more reliable high-speed applications with strong shock and thermal interaction.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.