Wind-Driven Ignition Behavior of Wildland Fuels: Experimental Insights Under Controlled Conditions

Wildfires are driven by complex interactions between fuels, ignition sources, and environmental conditions among which wind plays a critical role. This study investigates the influence of wind speed on the ignition behavior of wildland fuels using a controlled wind tunnel setup. Four fuel types (excelsior, bromus, avena, and wheatgrass) were exposed to stainless steel spheres as heated ignition sources under four wind conditions (0.5, 1.0, 1.5, and 2.0 m/s). The analysis focuses on key combustion parameters including ignition temperature, ignition delay, smoldering-to-flaming transition, burnout time, rate of spread (ROS), and heat release rate (HRR). Results show that higher wind speeds significantly increased ignition and peak temperatures while reducing ignition delay and transition times. For example, in wheatgrass fuels, flaming ignition temperature rose from ~ 472°C to ~ 610°C as wind speed increased from 0.5 to 2.0 m/s, with a concurrent decrease in smoldering-to-flaming transition time from 105 to 61 seconds. ROS increased notably with wind speed across all fuel types, reaching up to ~ 1.2 cm/s in excelsior at 2.0 m/s. Similarly, HRR values rose with wind, indicating more intense combustion; for instance, HRR in flaming ignition for excelsior peaked at ~ 3500 J/s at 2.0 m/s. The study highlights how wind-enhanced convective heat transfer and oxygen availability accelerate combustion dynamics and fire spread. These insights improve our understanding of wind-driven fire behavior and provide valuable input for predictive fire modeling, risk assessment, and wildfire mitigation strategies.