Laminar burning velocity of stoichiometric CH₄/air premixed flames at high-pressure and high-temperature

Experimental and numerical studies on laminar burning velocities of stoichiometric CH₄/air flames were performed at high pressure and high temperature. A stoichiometric CH₄/air mixture was diluted by helium in order to restrain the intrinsic flame instabilities occurring at high pressure. Measurements of laminar burning velocity for burner-stabilized flames were conducted by a technique employing particle tracking velocimetry (PTV) and planar laser induced fluorescence for OH radical (OH-PLIF) simultaneously, which measures the instantaneous local burning velocity. Laminar burning velocities were determined by the average values of local burning velocities in the region where the Karlovitz number are sufficiently small, meaning that the effect of flame stretch and curvature can be neglected. Numerical simulations were also conducted using a one-dimensional premixed flame code. Detailed reaction mechanisms and the 4-step reduced mechanism were examined, and their results were compared with experimental results to investigate the feasibility of predicting the flame characteristics at high pressure and high temperature, based on the reaction mechanisms.