Crossflow Speed and Ground Slope Influence on the Flame Structure for Stationary Methane Burners

Wildland fires are dangerous and complex processes whose dynamics are governed by numerous environmental variables. Two of these environmental variables, wind and ground slope, impact both the flame structure and rate of spread. While previous experimental research examined the individual effects of these two variables on fire dynamics, few studies have considered the concurrent effects of crossflow speed and ground slope. This study aims to examine the effects of crossflow speed and ground slope on the structure of stationary diffusion flames under highly controlled conditions. Sintered-bronze, rectangular methane burners with spanwise width of 0.2 m and aspect ratios of 200, 20, and 2 were used to produce stationary flame fronts. The burners were tested in an inclinable wind tunnel facility at crossflow speeds from 0.5 to 2 m/s and ground slope angles from -10 to +10 degrees. The flame structure and dynamics were captured using two high-speed cameras in a perpendicular orientation. Flame angle, flame length, and frequencies of downstream flame extensions were quantified from the side and top view videos. Additionally, the surface temperature distribution downstream of each of the burners was captured using an array of thermocouples embedded in an aluminum floor to examine the variations in downstream heating.