Experimental Study on the Ignition Behavior of Wildland Fuels Ignited by Heated Stainless-Steel Particles

Abstract

ABSTRACT Hot metal particles from activities like machining, grinding, and welding are significant ignition sources for wildland fuels. Thus, this study examines the effects of stainless-steel particle geometries and wildland fuel beds on wildfire ignition behavior. To this purpose, experiments have been conducted to investigate the impact of particle type, composition, diameter, number, and wildland fuel bed species on ignition behavior. Three common California wildland grass fuel species were studied: Bromus (Bromus diandrus), Tall Wheatgrass (Thinopyrum ponticum), and Avena Wildoats (Avena fatua). Various stainless-steel grades were tested as ignition particles. The findings from this study support prior research and indicate that increasing the quantity and diameter of ignition particles reduces ignition temperature and affects the type of ignition (flaming, smoldering, or none). Moreover, results from this study showed that decreasing the carbon content in stainless steel may lower the temperature required to reach wildland fuel ignition. In addition, wildland fuel species influenced ignition type and temperature. For instance, Bromus fuels had the lowest flaming ignition temperature at 320°C whereas Tall Wheatgrass and Avena ignited at 400°C and 380°C, respectively. Flaming ignition was primarily observed in Bromus fuels, while Avena and Tall Wheatgrass primarily supported smoldering ignition. This work asserts that species-specific fuel morphology, chemical, and thermal properties affect the flammability of grassy fuels when these are ignited by metal particles and observes that in addition to particle geometry, the chemical properties of ignition particles, such as carbon content, may also lay a key role in shapping ignition behavior.