Experimental study on flame trap by wire mesh of hydrogen/air premixed flame in meso-scale narrow tube

• This study investigated the behavior of a H 2/ air premixed flame trapped near a wire mesh inside a narrow tube, which depends on the flow condition. • The flame was quenched near the wire mesh after the flame continued to be trapped for 4–5 s under conditions with a low flow velocity. • In some conditions with ϕ = 0.65 and 0.7, after the flame continued to be trapped near the wire mesh for 52–161 s and flashback occurred. • The flashback occurs when the heat loss to the wire mesh decreases and the heat recirculation is enhanced. This study aims to clarify the behavior of a hydrogen/air premixed flame near a wire mesh inside a meso-scale narrow tube depending on the flow condition. In the experiments, we used a quartz-glass narrow tube with an inner diameter of 3.6 mm in which a stainless-steel mesh of 32 mesh/inch was installed. The flame behavior near the wire mesh was observed while a hydrogen/air mixture was continuously supplied to the tube. Under most of the conditions investigated, the flame continued to be trapped near the wire mesh even after reaching a steady state. However, under conditions with a flow velocity of approximately 4 cm/s or lower, the flame was quenched near the wire mesh after the flame continued to be trapped for a few seconds. These are mostly due to heat loss through the wire mesh. In some conditions with the equivalence ratios ϕ = 0.65 and 0.7, after the flame continued to be trapped near the wire mesh for a few minutes, the flame passed through the wire mesh and flashback before reaching a steady state. In addition, the time from the flame trap to the flashback varied depending on the flow velocity. This is because the heat loss at the wire mesh decreases, and the heat recirculation is enhanced while the flame continues to be trapped near the wire mesh. These findings suggest that the risk of flashback is increased for the flow condition where the flame arrester in the meso-scale tube promotes the heat recirculation.