CAREER: Flow Control with Cellular Materials

细胞材料的例子包括海绵骨、植物茎叶以及水生珊瑚。天然细胞材料通常是多功能的，并表现出独特的物理特性，如低密度，高强度和刚度，以及调节流体流动的能力。由于增材制造技术的进步，现在可以为工程应用创造这种多功能材料。本项目旨在开发用于被动流动控制的多孔细胞材料。适当设计的多孔材料有可能减少流动引起的噪音，减少表面摩擦，调节传热，控制分离或高速流动。由此产生的性能改进可以使飞机、水运船只和地面车辆受益。下面描述的研究工作将阐明支撑这些应用的基本流动物理学，并产生有助于设计用于流动控制的细胞材料的科学工具。该项目还有几个教育和推广组成部分，包括持续的本科生研究参与，对顶点高级设计项目的支持，以及与当地高需求公立学校的长期合作。这项研究将集中于更好地理解多孔基底上的湍流边界层流动。控制目标将是抑制近壁湍流，最终减少表面摩擦（即阻力）。这项研究涉及三个关键目标。首先，将开发低复杂性模型来预测具有特定体积特性（例如孔隙度和渗透率）的多孔材料如何改变近壁湍流。该模型将用于优化体积特性以抑制近壁湍流。然后，这些结果将用于设计和制造（通过3d打印）由模型确定的具有大块特性的细胞材料。该组件将天然细胞材料的宏观描述与实际可制造细胞几何形状的设计连接起来。最后，将采用多孔细胞状材料壁面的通道和边界层实验来测量湍流的统计和结构特征。除了提供对复杂各向异性多孔材料湍流物理的深入了解外，这些实验将作为模型的概念验证。总之，这些研究活动将创建一个紧密耦合的理论和实验框架，可以指导具有所需宏观特性的细胞材料的开发，以控制各种湍流。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。

Examples of cellular materials include spongy bone, plant stems and leaves, as well as aquatic corals. Natural cellular materials are often multi-functional and demonstrate unique physical properties such as low density, high strength and stiffness, and the ability to regulate fluid flow. Due to advances in additive manufacturing technology, it is now possible to create such multi-functional materials for engineering applications. This project aims to develop porous cellular materials for passive flow control. Appropriately designed porous materials have the potential to reduce flow-induced noise, decrease skin friction, regulate heat transfer, and control separated or high-speed flows. The resulting performance improvements could benefit aircraft, waterborne vessels, and ground vehicles. The research effort described below will clarify the fundamental flow physics that underpin these applications and generate scientific tools that can aid the design of cellular materials for flow control. The project also has several educational and outreach components, including sustained undergraduate research involvement, support for capstone senior design projects, and long-term collaboration with a local high-needs public school.The research will focus on gaining a better understanding of turbulent boundary layer flow over a porous substrate. The control objective will be to suppress the near-wall turbulence to ultimately reduce skin friction (i.e. drag). This research involves three key objectives. First, reduced-complexity models will be developed to predict how porous materials with specified bulk properties (e.g., porosity and permeability) modify the near-wall turbulent flow. The models will be used to optimize the bulk properties to suppress near-wall turbulence. These results will then be used to design and fabricate (via 3D-printing) cellular materials exhibiting bulk properties identified by the models. This component will bridge macroscopic descriptions of natural cellular materials with the design of actual manufacturable cell geometries. Finally, channel and boundary layer experiments with the porous cellular-like material walls will be used to measure the statistical and structural features of the turbulent flow. In addition to providing insight into turbulent flow physics over complex anisotropic porous materials, these experiments will serve as proof-of-concept validation for the models. Together, these research activities will create a tightly coupled theoretical and experimental framework that can guide the development of cellular materials with desired macroscopic properties to control a variety of turbulent flows.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.