Ignition propensity of structural materials exposed to firebrand in wildland-urban interface (WUI) fires

荒地-城市界面 (WUI) 火灾中暴露于火源的结构材料的着火倾向

基本信息

批准号：
1836428
负责人：
Ya-Ting Liao
金额：
$ 30万
依托单位：
Case Western Reserve University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2018
资助国家：
美国
起止时间：
2018-09-01 至 2022-08-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1836428&HistoricalAwards=false
关键词：
Ignition propensity structural materials exposed

项目摘要

This project will characterize the ignition process of materials caused by firebrand attacks, a key mechanism of wildfire spread into Wildland-Urban Interface (WUI) communities. Firebrands are small burning pieces lofted by flame plumes and transported by ambient winds. Although they are small, firebrands can travel in large groups for long distances from the fire front. These firebrands can shower unto structures in WUI communities far from the wildfire itself and therefore pose serious threats to human lives and properties. In this project, lab-scale experiments and computational modeling will be used to systematically study such phenomena. By providing a better understanding of firebrand attacks, this project will promote the development of new testing standards for building codes and materials. This work will contribute to the effort in increasing the safety of structures at the wildland-urban interface, such as optimal geometry of structure for mitigating fire risks.For a combustible solid subjected to external heating, ignition depends not only on the total energy input but also on the spatial distribution of the heating. For ignition due to firebrand attack, the distribution of firebrands and their individual shapes, sizes, and contact areas with the target structure will determine the distribution of heat flux on the structure surface. Environmental conditions (e.g., background radiant heating and air flow speed) also have a significant effect on the kinetics of the burning firebrands and the interactions between firebrands and the target structure. The goal of this study is to obtain a fundamental understanding of how these parameters affect the ignition propensity of a structure material. A combination of lab-scale experiments and computational modeling will be used. The experiment will involve firebrands burning under the influence of air flow and external radiant heating. Temperatures, burning durations, and heat release rates of the burning brands, as well as the temperature of the substrate, will be analyzed. The ignition propensity of the fuel bed will be characterized according to firebrand attributes and environmental factors. A combustion model will also be developed for simulating the thermo-kinetic process of each aspect of the firebrand attack. The simulation results will provide detailed information about gases and solids during the combustion process, thus facilitating the interpretation of the experimental observation. The numerical simulation will also allow the investigation of the underlying physics of these processes.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.

该项目将描述由火力攻击引起的材料的点火过程，这是野火蔓延到野火界面（WUI）社区的关键机制。火焰是小燃烧的小块，被火焰羽高出，并由环境风运输。尽管它们很小，但火牌可以远距离远距离旅行。这些火力可以在武装部队本身远离武力社区的建筑物中淋浴，因此对人类的生命和财产构成了严重威胁。在这个项目中，实验室规模的实验和计算建模将用于系统地研究这种现象。通过更好地了解火力攻击，该项目将促进建筑法规和材料的新测试标准的制定。这项工作将有助于提高荒野城市界面的结构安全性，例如用于减轻火灾风险的结构的最佳几何形状。对于受外部加热的可燃固体，点火不仅取决于总能量输入，还取决于加热的空间分布。对于由于火力攻击而引起的点火，火焰及其单个形状，大小和与目标结构的接触区域的分布将决定结构表面上的热通量的分布。环境条件（例如，背景辐射加热和空气流速）也对燃烧火焰的动力学以及火焰和目标结构之间的相互作用也有显着影响。这项研究的目的是获得对这些参数如何影响结构材料的点火倾向的基本理解。将使用实验室规模实验和计算建模的组合。该实验将涉及在空气流和外部辐射加热的影响下燃烧的火焰。将分析燃烧品牌的温度，燃烧持续时间和热量释放速率以及基板的温度。燃油床的点火倾向将根据火焰属性和环境因素来表征。还将开发一个燃烧模型，以模拟火力攻击的每个方面的热态过程。模拟结果将在燃烧过程中提供有关气体和固体的详细信息，从而促进实验观察的解释。数值模拟还将允许对这些过程的基本物理进行调查。该奖项反映了NSF的法定任务，并使用基金会的知识分子优点和更广泛的影响审查标准，被认为值得通过评估来获得支持。