Burning velocity measurements of methane-oxygen-argon mixtures and an application to extend methane-air burning velocity measurements

Abstract

Burning velocities of methane-oxygen-argon mixtures have been measured in two matched constant-volume chambers, one spherical and one cylindrical. Burning velocities in the spherical chamber were determined from the pressure rise using a thermodynamic model based on the conservation of mass and energy. Photographic observations made through end windows in the cylindrical chamber at early times were used to study the effects of flame curvature and stretch on the flame speed under constant pressure conditions. The cylindrical chamber was also used to investigate flame shape, cracking and wrinkling. Substitution of argon for the nitrogen in air increased the range of pressure and temperature at which measurements could be made. A correlation for the burning velocity of methane-oxygen-argon mixtures has been developed for the range of pressures from 1 to 40 atmospheres, unburned gas temperatures from 298 to 650 K and fuel-air equivalence ratios from 0.8 to 1.2. Using this correlation and previous results for methane-air mixtures, the burning velocities of methane-air mixtures have been extended to higher temperatures. The results are compared to other experimental measurements and theoretical predictions.