An investigation of the effect of crown fuel separation on the dynamics of multiple crown fire initiation in shrub fuels

Abstract

Multiple crown fire initiation is investigated via laboratory experiments and physical modeling techniques. The goal of this study is to determine the influence of separation distance between adjacent crown fuels on the process of fire transition from surface fuels to crown fuels, and between crowns. The experimental setup is designed to model two isolated crown fuels consisting of live chamise (Adenostoma Fasciculatum). During experimentation, only distance between crown fuels and wind speed is varied while efforts are made to maintain all other conditions constant. Crown separation distances investigated range from 0.1 m to 0.3 m and wind speeds range from 0.6 m/s to 1.9 m/s. Solid fuel temperature and air temperature within the crown fuel matrix is measured. Also recorded is the mass loss rate of the surface and crown fuels as a fire propagates across the experimental fuel bed. By investigating the ignition of multiple crowns we expect to gain a better understanding of the transition process. The physical modeling aspect of this investigation is based on a Large Eddy Simulation (LES).