Collaborative Research: Reaping the Whirlwind: Re-energizing Boundary Layers by Targeted Manipulation of Coherent Structures

合作研究：收获旋风：通过有针对性地操纵相干结构来重新激活边界层

• 批准号: 2129493
• 负责人: Michael Amitay
• 金额: $ 23.49万
• 依托单位: Rensselaer Polytechnic Institute
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-07-01 至 2024-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2129493&HistoricalAwards=false
• 关键词: Collaborative; Research; Reaping; Whirlwind; Re

In a turbulent flow, for example near the surface of an airplane wing or in the atmosphere as it flows over the Earth’s surface, there is a range of eddies of different sizes. The largest of these coherent eddies, called Large Scale Motions (LSMs), carry a significant portion of the turbulent kinetic energy and are largely responsible for mixing high-speed flow far away from the surface with the low-speed flow right near the surface. This mixing may be enhanced by selectively displacing the LSMs toward the surface, and this is very desirable in some applications. For example, bringing high-speed flow to the surface can keep a wing from stalling and losing its lift. The goal of this project is to prove via simulations and in matched experiments an approach to detect and manipulate LSMs to re-energize the near-surface flow. The success of the present approach is also expected to motivate the emergence of technologies such as controlling acoustic noise or heat transfer for underwater, ground-vehicles, or air-vehicles or combustion in turbomachinery. This project thus has the potential of initiating a new direction in turbulent flow control. The goal of this research is to develop an experimentally-validated system for active detection and manipulation of LSMs for turbulent boundary layer re-energization. Advances in the fundamental understanding of LSMs, actuator innovations, and advanced control theory make this goal achievable. The first step towards the goal is to demonstrate energizing a boundary layer by manipulating controlled, well-characterized, synthetically generated structures in well-coordinated boundary layer experiments and direct numerical simulations (DNS). The preliminary DNS successfully demonstrated optimization of control jet actuation using two different control methods, which deflected a prototypical LSM towards the surface. Preliminary work has created a suitable actuator based on a synthetic jet and demonstrated it in the lab. The specific tasks proposed in this collaborative 3-year project are: (1) develop and implement control algorithms to selectively move synthetically generated LSMs in matched experiments and DNS, (2) quantify the re-energization achieved by moving different kinds of LSMs to guide target prioritization, and (3) test and optimize the re-energization of a turbulent boundary layer with an eye toward separation control and wind power applications. The results of this project will be made publicly available through online platforms and enhanced classroom activity. The project will also help recruit graduate students from underrepresented groups and for several undergraduate research projects.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.

在湍流中，例如在飞机机翼表面附近或在地球表面的大气中，会产生一系列大小不同的涡流。这些相干涡流中最大的涡流被称为大尺度运动（Large Scale movements, lsm），它携带了很大一部分湍流动能，主要负责将远离地表的高速气流与靠近地表的低速气流混合在一起。这种混合可以通过选择性地将lsm移向表面来增强，这在某些应用中是非常理想的。例如，将高速气流带到地面可以防止机翼失速和失去升力。该项目的目标是通过模拟和匹配实验证明一种检测和操纵lsm以重新激活近地表流动的方法。目前方法的成功也有望激发诸如控制水下、地面车辆、空中车辆或涡轮机械燃烧的声学噪声或传热等技术的出现。因此，这个项目有可能在湍流控制方面开创一个新的方向。本研究的目标是开发一个实验验证的系统，用于主动检测和操纵湍流边界层再激活的lsm。对lsm的基本理解，执行器创新和先进的控制理论的进步使这一目标可以实现。实现目标的第一步是在协调良好的边界层实验和直接数值模拟（DNS）中，通过操纵受控的、具有良好特征的、合成生成的结构来演示边界层的赋能。初步的DNS成功地演示了使用两种不同的控制方法优化控制射流驱动，使原型LSM偏转到表面。初步工作已经在合成射流的基础上创造了一个合适的驱动器，并在实验室中进行了演示。在这个为期3年的合作项目中提出的具体任务是：(1)开发和实现控制算法，在匹配实验和DNS中选择性地移动综合生成的lsm；(2)量化通过移动不同类型lsm实现的再激励，以指导目标优先级；(3)测试和优化湍流边界层的再激励，着眼于分离控制和风力发电应用。该项目的成果将通过在线平台和强化的课堂活动向公众公布。该项目还将帮助从代表性不足的群体中招募研究生，并为几个本科生研究项目提供帮助。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。