Three-dimensional Modeling of Combustion and Pollution from Wildland Fires

这项研究代表了科罗拉多大学、国家大气研究中心（NCAR）和蒙大拿州密苏拉市美国农业部林业局山间火灾科学实验室的联合倡议，旨在显著提高现有的模拟大气-火灾耦合的能力，以应对野火中可能发生的强烈燃烧。具体任务将包括：(1)基于火焰表面积的描述开发湍流燃烧的亚网格尺度模型。这将使更准确地处理流体动力-燃烧相互作用成为可能。(2)垂直和水平对齐的涡度可以作为从火中升起和喷出燃烧物质的手段，从而导致斑点。首先，将使用NCAR现有大气-火灾模型的后处理速度场，对浮起、空气动力学和火焰沉降进行拉格朗日处理。利用这一点，将建立一个合适的欧拉模型。(3)基于基本守恒原理，将建立一个描述固体燃料床干燥、热解和炭氧化的简化模型。(4)最后，将开发一个简化的烟雾模型，使一氧化碳和颗粒物浓度能够量化。这是一个重要的组成部分，将有助于模型评估和测试替代烟雾管理方案。开发的子模型将集成到现有的三维中尺度大涡模拟中，该模拟已经在NCAR开发了20年，最近与山间火灾科学实验室合作。最近完成和正在进行的实地实验将使用数字红外相机对机会火进行从亚米到公里的范围内的观测。有了现有的数据，这些实验结果将被用作完全集成模型的试验台。预期结果将有助于森林管理机构改进灭火战略和规划规定的焚烧。这些进展将对从事湍流燃烧和污染建模领域的科学界产生根本性影响。

This research represents a joint initiative between the University of Colorado, the National Center for Atmospheric Research (NCAR), and the Intermountain Fire Sciences Laboratory of the U.S. Department of Agriculture Forest Service in Missoula, Montana, to significantly improve existing capabilities to model atmosphere-fire coupling as might occur during intense burning in wildland fires. Specific tasks will include: (1) Development of subgrid scale models for turbulent combustion based on a description of the flame surface area. This will enable a more accurate treatment of fluid dynamic-combustion interactions. (2) Vertically and horizontally aligned vorticity can act as means of lofting and ejecting burning material from the fire that could lead to spotting. Initially, using post-processed velocity fields from NCAR's existing atmosphere-fire model, a Lagrangian treatment of lofting, aerodynamics and settling of firebrands will be carried out. Using this, a suitable Eulerian model will be developed. (3) A simplified model to describe drying, pyrolysis, and char oxidation from a solid fuel bed will be developed, based on basic conservation principles. (4) Lastly, a simplified smoke model that will allow quantification of carbon monoxide and particulate concentrations will be developed. This is an important component that will assist with model evaluation and to test alternative smoke management scenarios.The sub-models developed will be integrated into an existing three-dimensional, mesoscale large eddy simulation that has been under development for twenty years at NCAR, with recent collaboration with the Intermountain Fire Sciences Laboratory. Recently completed and ongoing field experiments will provide observations on fires of opportunity ranging in scale from sub-meter to kilometers using a digital infrared camera. With available data these experimental results will be used as a test bed for the fully integrated model. Results are expected to assist forest management agencies to improve fire-fighting strategies and for planning prescribed burns. These advances will have a fundamental impact on the scientific community working in the areas of turbulent combustion and pollution modeling.