The Effects of Turbulence of Spark-Ignited, Ultra Lean, Premixed Methane-Air Flame Growth in a Combustion Chamber

The effects of turbulence on 60% stoichiometric, premixed methane-air flame propagation were investigated using high speed schlieren video and pressure trace analyses. The mixtures were centrally spark-ignited at 300 K and 101 kPa in a 125 mm cubical chamber. Turbulence was up to 2 m/s intensity with 2 to 8 mm integral scale. With quiescent mixtures, buoyancy convected the slow-burning flame upward onto the upper wall, resulting in dramatic heat loss. With turbulence, the burning rate was enhanced profoundly, though partial flame quenching resulted in cyclic variability at higher turbulence levels. Despite this partial quenching, these ultra-lean flames generally resisted total extinguishment over the conditions tested.