SGER: Auto-ignition of Wood

University Of Maryland, College Park, College Park MD

Investigators

Abstract

Project Summary: Auto-ignition of wood This is a Small Grant for Exploratory Research. A model for autoignition of wood is developed and solved numerically. The model considers physical and chemical processes in both solid and gas phases. The char surface oxidation, important when the incident heat flux to the solid surface is low, is included in the solid-gas interface boundary conditions. The numerical code can reproduce the experimental results for autoignition and ultimately can explain the underlying physical and chemical processes governing the autoignition of wood. Auto-ignition is a significant mechanism in the spread and growth of fire. It is of fundamental interest, but its complexity has prevented a definitive study of the important mechanisms that control it. Although the focus of this study is wood, the proposed modeling can relate to other charring and non-charring solids as well. The heating of wood in an oxygen atmosphere leads to exothermic surface oxidation and thermal decomposition of the virgin material. Smoldering ignition can occur at the surface, and flaming ignition is also possible. These two forms of ignition have not previously been distinguished in the process of autoignition. Broader Impact This fundamental work is important to the overall safety of the public and infrastruture. Significantly, it embraces the problem of spread in forest fires since this spread involves the radiant heating of discrete woody material causing oxidation and flaming. From an educational point of view, the results of this work are transmitted to fire-protection engineering students in a unique program. This result will be the first of its kind in addressing both the surface and gas-phase ignition processes, and is significant to public safety and the spread of fire in forests and structures.