Effect of spark duration on explosion parameters of methane/air mixtures in closed vessels

The paper outlines an experimental study on influence of the spark duration and the vessel volume on explosion parameters of premixed methane-air mixtures in the closed explosion vessels. The main findings from these experiments are: For the weaker ignition the spark durations in the range from 6.5. μs to 40.6. μs had little impact on explosion parameters for premixed methane-air mixtures in the 5. L vessel or 20. L vessel; For the same ignitions and volume fractions of methane in air the explosion pressures and the flame temperatures in both vessels of 5. L and 20. L were approximately the same, but the rates of pressure rises in both vessels of 5. L and 20. L were different; The explosion indexes obtained from the measured pressure time histories for both vessels of 5. L and 20. L were approximately equal; For the weaker ignition with the fixed spark duration 45. μs the ignition energies in the range from 54. mJ to 430. mJ had little impact on the explosion parameters; For the same ignition and the volume fractions of methane in air, the vessel volumes had a significant impact on the flame temperatures near the vessel wall; The flame temperatures near the vessel wall decreased as the vessel volumes increased.