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.