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

高速流动是非常复杂的，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中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-结构相互作用响应模式，该模式取决于力的历史，并且与其他类似系统显著不同。这个联合计算和实验项目的目的是提供一个深刻的理解，在高速流动的流体-结构相互作用的关键因素，并确定新的非线性动态响应模式，由于冲击和加热的柔性表面之间的相互作用。该项目将包括重要的教育和外展活动，包括与当地社区的本科生研究项目和K-12外展项目的多元化群体进行接触。该项目旨在通过调查一类涉及平移冲击和热梯度的新场景，填补目前在理解流体-热-结构相互作用方面的空白。目前，我们的理解主要限于在小长度尺度的流动变化明显短于界面长度的情况。该项目通过探索特定速度下的冲击波平移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，填补了我们知识中的差距。 该项目将通过严格的实验和计算研究来实现这些目标，重点是三个具体任务：（i）使用浸没边界方法开发和验证一个计算模型，用于流体-热-结构相互作用的综合研究，（ii）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，以及（iii）通过制定基于理论能量和基于动量的分析方法来解开复杂的物理学。通过该项目获得的知识将使开发和设计更可靠的高速应用与强烈的冲击和热相互作用。该奖项反映了NSF的法定使命，并已被认为是值得通过评估使用基金会的知识价值和更广泛的影响审查标准的支持。

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.