Abstract
The radiative heating of small particles in a flammable atmosphere by laser light may lead to ignition and explosion. The mechanisms of ignition and detonation of quiescent methane/air mixtures caused by a radiatively heated inert particle involves a set of chemical reactions among the gas-phase species. A system of ordinary differential equations that comprises the net reaction rates of the species, which are initially present in the system, and the products of their reversible reactions is solved for the entire inflammability range of methane with air under isothermal conditions and within the temperature region of interest (800-1000 K). Two criteria tests are carried out to identify the chain initiating reaction. The first criterion tests the contribution a given reaction made to the main chain branching while the second criterion tests its contribution to the total heat release. It is found that the reaction, O2 + CH4→HO2 + CH3 satisfies the criteria at all grid points of the calculation. A simplified kinetic scheme is adopted and a system of differential equations, representing the net reaction rates of all species included in the scheme is solved. The data are used in the explosion-delay time calculations.
