Enhancement effects of methane/air explosion caused by water spraying in a sealed vessel

• We designed an entirely closed visual vessel for gas explosion with water mist.
• We examined the effects of drop sizes, spraying time and methane concentration.
• Spraying could cause flame acceleration and brightness enhancing.
• Larger drop sizes could lead to more violent explosion reaction.
• The enhancement effect remains changeless with the increasing of spraying time.

Experiments about the influence of ultrafine water mist on the methane/air explosion were carried out in a fully sealed visual vessel with methane concentrations of 8%, 9.5%, 11% and 12.5%. Water mists were generated by two nozzles and the droplets' Sauter Mean Diameters (SMD) were 28.2 μm and 43.3 μm respectively which were measured by Phase Doppler Particle Anemometer (PDPA). A high speed camera was used to record the flame propagation processes. The results show that the maximum explosion overpressure, pressure rising rate and flame propagation velocity of methane explosions in various concentrations increased significantly after spraying. Furthermore, the brightness of explosion flame got much higher after spraying. Besides, the mist with a larger diameter had a stronger turbulent effect and could lead to a more violent explosion reaction.