Burner platform for sub-atmospheric pressure flame studies

Hencken burner flames at sub-atmospheric pressure were characterized experimentally to show their unique structure for detailed flame studies. Methane-air flames at 16.7 kPa were shown to be lifted and stably anchored at significant distances (up to 18 mm) above the burner surface, while maintaining a flat and one-dimensional laminar structure and near adiabatic conditions. Particle image velocimetry was used to identify the weakly stretched regime (strain rate = 20-70 s−1) of the flames, as well as the flame speeds, while OH number densities were measured through laser-induced fluorescence and calibrated through absorption. The flame speeds and quantitative OH profiles were compared to one-dimensional and two-dimensional flame simulations using the chemical kinetic mechanisms of USC Mech II and GRI-3.0 and showed good agreement. Flames produced by a Hencken burner at sub-atmospheric pressure were shown to accurately represent a steady, laminar, nearly one-dimensional, minimally curved, weakly stretched, and near adiabatic flame, which could be compared to one-dimensional freely-propagating flame simulations with minimal corrections and extrapolations.