Effects of cross-wise obstacle position on methane–air deflagration characteristics

•Three obstacle configurations with different cross-wise positions are investigated.•High-speed flame images and overpressures were recorded and analyzed.•Cross-wise obstacle positions have significant effects on deflagration characteristics.•Flame speeds and overpressures for both the central and staggered configurations are greater.•May help designers in optimizing the internal layout of obstacles in practical processes.

A vented chamber, with internal dimensions of 150 mm × 150 mm × 500 mm, is constructed in which the premixed methane–air deflagration flame, propagating away from the ignition source, interacts with obstacles along its path. Three obstacle configurations with different cross-wise positions are investigated. The cross-wise obstacle positions are found to have significant effects on deflagration characteristics, such as flame structure, flame front location, flame speed, and overpressure transients. The rate of flame acceleration, as the flame passes over the last obstacle, is the highest at the configuration with three centrally located obstacles, whereas the lowest is observed at the configuration with three obstacles mounted on one side of the chamber. Compared with the side configuration, the magnitude of overpressure generated increases by approximately 80% and 165% for the central and staggered configurations, respectively. Furthermore, flame propagation speeds and generated overpressures for both the central and staggered configurations are greater, which should to be avoided to reduce the risk associated with turbulent premixed deflagrations in practical processes.