On the ignition of fuel beds by firebrands

Abstract

SUMMARYAn experimental apparatus has been built to investigate the ignition of fuel beds as a result of impact with burning firebrands. The apparatus allowed the ignition and deposition of both single and multiple firebrands onto the target fuel bed. The moisture content of the fuel beds used was varied, and the fuels considered were pine needle beds, shredded paper beds and crevices constructed of cedar shingles. Firebrands were simulated by machining wood (Pinus ponderosa) into small disks of uniform geometry and the size of the disks was varied. Firebrand simulation was necessary because it is difficult to capture and characterize firebrands from an actual burning object. The firebrand ignition apparatus was installed into the fire emulator/detector evaluator to investigate the influence of an air flow on the ignition propensity of fuel beds. The results of this study are presented and compared with relevant studies in the literature.

Ignition of Combustible Fuel Beds by Hot Particles: An Experimental and Theoretical Study

“…However, four flaming embers were not capable of igniting hardwood at 11% moisture content. Similar results are found using disk shaped embers [4,5] where flaming ignition occurred only when flaming embers are dropped. It was also observed that multiple flaming embers resulted in flaming ignition where single embers would cause no ignition.…”

“…This complex process depends on several factors, including the size and state of the brand or particle (temperature, smoldering/ glowing, flaming), the characteristics of the fuel bed on which it lands (temperature, density, porosity, moisture content), and environmental conditions (temperature, humidity, wind velocity). Ignition of fuel beds by fire brands and heated surfaces has been studied primarily experimentally, in particular by workers at NIST [4][5][6][7]. Studies on ignition by metal particles have been reported by Rowntree and Stokes [2,3].…”

“…Only a few studies have examined the critical conditions that can lead to fire initiation after the landing of a firebrand or particle on a particular fuel bed. These studies are primarily experimental in nature [2][3][4][5][6][7][8], and no comprehensive theoretical studies have yet been conducted to analyze the problem or develop generalized predictive tools. Consequently, previous models of wildland fire propagation [9][10][11] have limited capabilities to predict the initiation of spot fires.…”

Assessing the flammability of surface fuels beneath ornamental vegetation in wildland–urban interfaces in Provence (south-eastern France)

“…Regarding ornamental vegetation, Long et al (2006a) provided flammability data for horticultural beds by evaluating the effect of the type of mulch, planting composition and drought conditions on fire spread and heat release in both field and controlledenvironment conditions. Several experiments were carried out on firebrands but very few used surface fuels (Manzello et al 2006a(Manzello et al , 2006b(Manzello et al , 2007(Manzello et al , 2008(Manzello et al , 2009Ganteaume et al 2011b). …”

Mathematical Model of Heat Transfer in Layered Structure of Human Skin Influenced by Heated up to High Temperatures Particle

“…Majority of such damages depend on source temperature and influence time. Heated up to high temperatures particles of metals and nonmetals are probable sources of high temperature at natural and technogenic fires [5][6][7][8].…”