Kinetic nature of blue flames in the autoignition of methane

Kinetic calculations within the framework of detailed reaction mechanisms showed that the blue flames observed during autoignition of methane in an internal combustion engine are combined cool-blue flames. In the course of methane oxidation, methyl hydroperoxide CH₃O₂H and hydrogen peroxide H₂O₂ appear and accumulate almost simultaneously. The partial decomposition of these species yields a hydroxyl OH concentration peak, thereby giving rise to a local acceleration of the oxidation reaction, accompanied by luminescence. Kinetic curves for the main products were obtained and the boundaries of cool-blue flames were determined, which turned out to be in satisfactory agreement with the experimental data.