Investigation of delayed onset of flashback of H₂/air premixed flames with different inner diameters of meso-scale tubes with wire mesh

抄録

This study aims to clarify the effect of inner-diameter differences on the delayed onset of flashback, where the H₂/air premixed flame, after being trapped near a wire mesh, passes through the mesh and flashback occurs with a time delay. In the experiment, as the inner diameter decreased, the flashback range decreased, and the time from the flame trap near the mesh to the flashback increased. This is because the heat loss to the tube wall increased as the inner diameter decreased. On the other hand, the mesh temperature just before the start of flashback decreased as the inner diameter decreased. This is because heat recirculation is greater as the inner diameter decreases due to the longer time from the flame trap near the mesh to the flashback and the low flow rate of the mixture. Additionally, flame-front position was calculated using image analysis, and flame propagation behavior was examined in terms of the apparent flame speed. As a result, the findings of this study clarified the effects of heat loss and heat recirculation differences due to variations in the inner diameter on flame behavior near the mesh. This study provides knowledge on flame behavior near the flame arrester under flow conditions and contributes to the safe use of hydrogen.