EAGER: Time-Resolved Measurements and Control of Vortex Breakdown via Heat Addition

EAGER：通过加热进行涡流破坏的时间分辨测量和控制

• 批准号: 2152596
• 负责人: Anya Jones
• 金额: $ 26.6万
• 依托单位: University of Maryland, College Park
• 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: 2021-12-15 至 2024-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2152596&HistoricalAwards=false
• 关键词: EAGER; Time; Resolved; Measurements; Control

This project was inspired by the discovery and ongoing study of the blue whirl, an apparent breakdown mode of a fire whirl in which it unexpectedly transitions to a small and seemingly benign blue flame. The blue whirl produces no soot and minimal pollutants, suggesting optimal burning and a potential source of clean energy. Creating a blue whirl without having to pass through the fire whirl state would enable a safe and clean form of hydrocarbon combustion that could be used in combustors, for propulsion, or for controlled burns (e.g., oil spill clean-up). More broadly, because vortex breakdown occurs in a wide variety of applications, a better understanding and ability to control and predict its dynamics has broad implications for many fluid dynamics systems affected by this instability. Controlling vortex breakdown would enable higher force production and enhance aerodynamic stability on wings and blades ranging from small-scale micro air vehicles to large-scale wind turbines, as well as more robust pump operation in cooling and emergency operations. This project aims to characterize and quantify the process of vortex breakdown in an incompressible non-reacting flow, and to identify mechanisms by which breakdown might be controlled via a new type of experiment wherein energy (in the form of heat) is introduced into the core of a vortex flow. The objective of this project is to experimentally demonstrate the effect of heat injection on vortex breakdown in a non-reacting incompressible flow, and to evaluate the parameter space over which heat addition has a measurable effect on the breakdown process and final state of the flow. A new type of vortex breakdown experiment will be developed to enable time-resolved velocity field measurements in a swirling flow with variable temperature (and thereby density) gradients. Complementary numerical simulations (performed by collaborators X. Zhang and E. Oran) will provide guidance in the development of the experimental facility and test matrix, and will make it possible to explore regions of the parameter space not easily achieved in the laboratory. Results from these experiments will include quantitative time-resolved measurements of the changes in flow structure during the process of vortex breakdown, with and without heat injection. The proposed experiments are expected to provide new physical insight into the process and mechanisms of vortex breakdown to inform theories and scaling laws, allowing for a generalization of the results gained here towards new methods of vortex control.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.

这个项目的灵感来自于对蓝色漩涡的发现和正在进行的研究，这是一种明显的火焰漩涡的分解模式，它意外地转变成一个小的、看似良性的蓝色火焰。蓝色漩涡不会产生烟尘和最小的污染物，表明最佳燃烧和潜在的清洁能源来源。创造一个不需要经过火焰漩涡状态的蓝色漩涡将使碳氢化合物燃烧成为一种安全和清洁的形式，可用于燃烧器，推进或控制燃烧（例如，溢油清理）。更广泛地说，由于漩涡破裂发生在各种各样的应用中，更好地理解和控制和预测其动力学的能力对受这种不稳定性影响的许多流体动力学系统具有广泛的意义。控制旋涡破裂可以产生更高的力，增强从小型微型飞行器到大型风力涡轮机的机翼和叶片的空气动力学稳定性，以及在冷却和紧急操作中更强大的泵运行。本项目旨在描述和量化不可压缩非反应流中涡旋击穿的过程，并通过一种新型实验来确定击穿可能被控制的机制，其中能量（以热的形式）被引入涡旋流的核心。本项目的目的是通过实验证明热注入对非反应不可压缩流动中涡击穿的影响，并评估热添加对流动的击穿过程和最终状态具有可测量影响的参数空间。一种新型的涡旋击穿实验将被开发，以使时间分辨速度场测量具有变温度（从而密度）梯度的旋涡流。互补的数值模拟（由合作者X. Zhang和E. Oran进行）将为实验设备和测试矩阵的开发提供指导，并将使探索在实验室中不易实现的参数空间区域成为可能。这些实验的结果将包括在有热注入和没有热注入的情况下，对涡旋破裂过程中流动结构变化的定量时间分辨测量。所提出的实验有望为涡旋破裂的过程和机制提供新的物理见解，为理论和标度定律提供信息，并允许将这里获得的结果推广到涡旋控制的新方法。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。