Ignition and explosion behaviour of methane/air mixtures caused by a radiatively heated inert particle

An experimental and modeling study of the ignition and explosion behavior of quiescent methane/air mixtures caused by a radiatively heated inert particle was carried out. The initial methane content was from 6 to 14 vol % and the total initial pressure of the gas was maintained constant at 1 atm. The explosion-delay time depended exponentially on the radiative power flux and tended to infinity at the critical values of the power flux. There was a tendency for the explosion-delay time to increase with increasing particle mass at fixed laser power flux and a stoichiometric mixture of methane and air. The explosion-delay time tended to infinity as the gas mixture composition approached the extremities of the flammability limits, while the minimum time occurred at the stoichiometric methane/air ratio. The numerical simulations correlated well with the experimental values if the correlation was included. However, the absence of such a factor led to significantly higher values (by a factor of ten) of the critical radiation power flux. Original is an abstract.