CAREER: Morphing Surfaces for Flow Control

CBET-0747672 McKeon这项综合研究和教育研究调查与边界层流动和变形表面(这里定义为能够对墙边界条件产生微小的、分布的或离散的、形态或几何扰动的薄皮肤)相互作用的物理问题。要解决的基本问题包括：通过变形表面可以很好地操纵边界层的特征，通过这种新的激活方法可以获得对流体物理的额外基本理解，以及研究生应该如何最好地为这种跨学科研究做好准备？一种跨学科的方法将侧重于：确定现在可以用活性材料询问的新区域中的流动物理；现场表征边界层流动和变形表面之间的相互作用；以及使用表面变形作为闭环控制的前驱来研究开环致动。可单独寻址的微或纳米致动器阵列将被一个连贯的表面或能够改变形态或局部几何形状的小范围适应的“皮肤”所取代。适当设计的变形表面的激活代表最小的控制努力，潜在的相对简单的模型将输入与流动中的结果结构变化联系起来。这项研究将把我们对接受性流动中的流动物理的理解扩展到一个参数范围，在一些新的材料出现之前，这个参数范围是以前无法获得的，或者可能是想象不到的。在引入与时间相关的壁面运动后，经典假设可以重新考虑正则流，并为未来的闭环系统控制工作提供潜在的激励手段。在变形表面上的实验也提供了关于静态粗糙壁面、边界层中的混合和涡量通量的基本问题的进一步洞察。更广泛的影响解决了环境问题，并通过人为操纵边界层结构对车辆边界层进行主动控制或优化，扩大了飞行器的性能。这项研究将展示如何在不增加重量或结构惩罚的情况下实现这一点，并最终导致新车的设计特点。与活性材料行业和一家领先的控制研究人员的合作寻求联合多个领域来解决这一高度跨学科的话题。教育目标是开发一种流动控制的协同培训计划，适合于解决这里描述的研究，并培养研究生研究人员处于与流动控制相关的传统学科之间的中间地带，包括流体力学、控制、动力学和固体力学。这将以研究生水平的课程达到高潮，该课程旨在统一实验、计算和建模方法，以解决高级流量控制问题。外展将以大众对流体动力学的兴趣为目标，重点是高中年龄的女孩，并继续致力于本科生的研究参与。

CBET-0747672McKeonThis integrated research and education study investigates the physics associated with the interaction of boundary layer flows with morphing surfaces (defined here as thin skins capable of generating small, distributed or discrete, morphological or geometrical perturbations to the wall boundary condition). Fundamental questions to be addressed include how well can the characteristics of a boundary layer be manipulated via a morphing surface, what additional fundamental understanding of fluid physics can be gained from this new means of activation and how should graduate students best be prepared for this interdisciplinary research? An interdisciplinary approach will focus on: identification of the flow physics in new regimes that can now be interrogated using active materials; in situ characterization of the interaction between boundary layer flows and morphing surfaces; and investigation of open-loop actuation using surface morphing as a precursor to closed-loop control. Arrays of individually-addressable micro- or nano- actuators will be replaced with a coherent surface, or "skin" capable of either morphological changes or small adaptation of local geometry. Activation of properly designed morphing surfaces represents minimal control effort, with the potential for relatively simpler models relating the input to resultant structural changes in the flow. This research will expand our understanding of flow physics in receptive flows into a parameter range not previously accessible, or perhaps imaginable, before the advent of some newer materials. Classical hypotheses can then be revisited for canonical flows after the introduction of time-dependent wall motion and providing potential means for actuation for future closed-loop control work. Experiments on morphing surfaces also promise further insight into fundamental questions concerning a statically rough wall, mixing and vorticity flux in boundary layers. Broader impacts address environmental concerns and expanded air vehicle performance using active control or optimization of vehicular boundary layers via artificial manipulation of the boundary layer structure. This research will show how this could be achieved without large weight or structural penalties, and ultimately leading to a design feature for new vehicles. Collaborations with the active materials industry and a leading controls researcher seek to unite multiple fields to address this highly interdisciplinary topic. The educational goal is to develop a synergistic training scheme in flow control, suitable for addressing the research described here and educating graduate researchers to inhabit the middle ground between traditional disciplines associated with flow control, including fluid mechanics, control, dynamics and solid mechanics. This will culminate with a graduate level course designed to unify experimental, computational and modeling approaches to tackle advanced flow control problems. Outreach will target general public interest in fluid dynamics, with emphasis on girls of high school age and a continuing commitment to undergraduate research participation.