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.

该项目的灵感来自于对蓝色漩涡的发现和正在进行的研究，蓝色漩涡是火漩涡的一种明显的分解模式，其中它意外地转变为小而看似良性的蓝色火焰。蓝色旋风不产生烟灰和最少的污染物，表明最佳燃烧和潜在的清洁能源来源。无需经过火涡旋状态即可产生蓝色涡旋，这将实现一种安全、清洁的碳氢化合物燃烧形式，可用于燃烧室、用于推进或用于受控燃烧（例如，溢油清理）。更广泛地说，由于涡流破裂发生在各种应用中，因此更好地理解和控制和预测其动力学的能力对于受这种不稳定性影响的许多流体动力学系统具有广泛的影响。控制涡流破坏将能够产生更大的力，并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稳定性，以及在冷却和紧急操作中更强大的泵操作。该项目旨在表征和量化不可压缩非反应流中涡流破裂的过程，并确定通过一种新型实验控制破裂的机制，其中能量（以热的形式）被引入核心的涡流。该项目的目的是通过实验证明热注入对非反应不可压缩流中涡流破裂的影响，并评估参数空间，在该参数空间上，热添加对流的破裂过程和最终状态具有可测量的影响。将开发一种新型的涡流破坏实验，以实现在具有可变温度（以及密度）梯度的旋流中进行时间分辨速度场测量。补充数值模拟（由合作者 X.Zhang 和 E.Oran 进行）将为实验设施和测试矩阵的开发提供指导，并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或没有热注入的情况下涡流破坏过程中流动结构变化的定量时间分辨测量。拟议的实验预计将为涡流破坏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，从而将此处获得的结果推广到涡流控制的新方法。该奖项反映了 NSF 的法定使命，并已被通过使用基金会的智力优点和更广泛的影响审查标准进行评估，认为值得支持。