Detonations in hydrogen-methane-air mixtures in semi confined flat channels

The aim of this work was to determine the influence of methane addition on the critical layer thickness h* and its relation to detonation cell size (λ) for stable detonation propagating in semi-confined, non-obstructed channel filled with uniform, stoichiometric hydrogen-methane-air mixtures. Three types of gaseous mixture composition were used: 0%, 5% and 10% of methane volume fraction in the mixture with hydrogen. The critical height h*, detonation cell size λ and critical relation h*/λ were defined for each investigated mixture showing that detonation in stoichiometric hydrogen-air mixture may propagate in semi-open channel only when the channel height is very close to, or exceeds, 3 cell sizes. Methane addition to the investigated combustible mixture increases the critical h*, however h*/λ ratio increases as well to 3.1 and 3.4 for 5% and 10% methane fraction, respectively.