Formation of an overdriven detonation wave in the flow of methane–oxygen mixtures in a variable cross section channel

The formation of an overdriven detonation wave in methane-oxygen mixtures in an axially symmetrical channel with a variable cross section was experimentally investigated. The ignition of gas mixture was carried out using the spark gap, located at the closed end of the channel. To create the overcompressed shock detonation wave, the decay of the stationary detonation wave was performed at the transition to the channel of a larger cross section. The created complex of shock wave and flame front, moving behind it, propagated in a channel with conical narrowing. The formation of the overdriven detonation wave, with parameters exceeding the parameters of Chapman–Jouguet stationary detonation by a few times, was registered at the outlet of conical narrowing. The rates and pressures on the front of the detonation wave were determined, depending on the mixture composition. The sizes of detonation cells, diagrams of compression waves propagation, flame front, and detonation wave in a combustion chamber, depending on the mixture composition, were presented.