Control of Vortex Breakdown and the Blue Whirl

涡破裂和蓝旋涡的控制

基本信息

批准号：
2050771
负责人：
Elaine Oran
金额：
$ 42万
依托单位：
Texas A&M Engineering Experiment Station
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：
2021-08-01 至 2024-07-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=2050771&HistoricalAwards=false
关键词：
Control Vortex Breakdown Blue Whirl

项目摘要

Fire whirls are dangerous, rapidly whirling flames that arise naturally in wildfires. When they do occur, they can be up to a kilometer tall and very destructive. Fire whirls can lift and throw burning material and generate fast winds that quickly spread the fire. Under the right controlled laboratory conditions, however, a fire whirl can transition into a beautiful, benign, small, blue flame called a blue whirl. These blue whirls can burn many different types of hydrocarbon fuels, either in gaseous or liquid form, while producing minimal pollutants and no soot at all. Such green-combustion properties are optimal for burning hydrocarbons, which make blue whirls a potential source of truly clean combustion energy. To use the blue whirl for practical applications, though, more needs to be understood about its structure, how it forms, and how to control it. This research project aims to understand how the blue whirl evolves naturally from a fire whirl and how to control it. The results of these investigations should reveal how to bypass the dangerous fire-whirl stage for creating the blue whirl, and the research should provide fundamental knowledge about swirling flows, which would benefit other related systems. This research project will train several early-career researchers, including a postdoctoral researcher and several graduate students.Previous studies led to the discovery of the existence of the blue whirl, its flame structure, and some of its dynamic properties. An important observation was that the blue whirl emerges from a fire whirl that goes unstable through a process known as vortex breakdown, which is a fluid transition leading to various possible modes of swirling flow. The objective of this research project is to focus on the vortex-breakdown transition and use large-scale numerical models to investigate whether it is possible to control the evolution to different modes. More specifically, the researchers will consider several different types of swirling flows subject to vortex breakdown. One type is a swirling flow with localized heat changes in the region of vortex breakdown. Here, the researchers hope to investigate and quantify how heat changes introduced into the vortex-breakdown process affect the transition to different modes. Another type of swirling flow to be investigated is a chemically reactive flow that produces flames such as the blue whirl. The researchers anticipate finding information on how to control the blue whirl and to enable its use for power generation and fuel spill clean-up. These studies will provide a fundamental understanding of the system that is needed to control vortex breakdown in other related applications, such as controlling instability on highly swept wings and swirl combustors. The new numerical algorithms and physical models developed from this research project will add to the general computational ability to simulate low-speed reactive complex flow systems.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.

火旋转是危险的，在野火中自然出现的旋风迅速。当它们确实发生时，它们可能高达一公里，非常具有破坏性。火旋转可以举起并扔掉燃烧的材料，并产生迅速散布火的快风。然而，在右侧的受控实验室条件下，旋转可以过渡为美丽，良性，小的，蓝色的火焰，称为蓝色旋转。这些蓝色旋转可以以气态或液体形式燃烧许多不同类型的烃燃料，同时产生最小的污染物，而根本没有烟灰。这种绿色燃烧特性对于燃烧碳氢化合物是最佳的，这使蓝色成为真正清洁燃烧能的潜在来源。但是，要将蓝色旋转用于实际应用，需要了解更多有关其结构，形成方式以及如何控制它的情况。该研究项目旨在了解蓝色旋转如何从火旋转以及如何控制它的情况下自然发展。这些调查的结果应揭示如何绕过创建蓝色旋转的危险旋转阶段，并且研究应提供有关旋转流的基本知识，这将使其他相关系统受益。该研究项目将培训几位早期研究人员，包括一名博士后研究人员和几位研究生。预防研究导致发现了蓝旋转的存在，其火焰结构及其某些动态特性。一个重要的观察结果是，蓝色旋转是从旋转的旋转中出来的，该旋转通过称为涡流分解的过程不稳定，这是一种流体过渡，导致了各种可能的旋流方式。该研究项目的目的是专注于涡流破裂的过渡，并使用大规模数值模型来研究是否有可能控制对不同模式的演变。更具体地说，研究人员将考虑受涡流崩溃的几种不同类型的旋流流。一种类型是旋转流，在涡流分解区域中具有局部热变化。在这里，研究人员希望调查并量化如何引入涡旋破裂过程中的热变化会影响到不同模式的过渡。要研究的另一种类型的旋流流是一种化学反应性流动，会产生诸如蓝旋流之类的火焰。研究人员期望找到有关如何控制蓝色旋转的信息，并使其用于发电和燃油漏油的使用。这些研究将提供对控制其他相关应用中涡流分解所需的系统的基本理解，例如控制高度扫荡的机翼和漩涡燃烧器的不稳定性。该研究项目开发的新的数值算法和物理模型将增加一般计算能力，以模拟低速反应性复杂流动系统。该奖项反映了NSF的法定任务，并认为使用基金会的智力优点和更广泛影响的评估标准，认为值得通过评估来获得支持。