10. Combustion and Reacting Flows

In this study, we developed a system that changes the swirl vane angle at the inlet of a cylindrical premixed combustor over time according to the flame behavior while keeping the air ratio and flow rate, to suppress the flashback behavior of a premixed flame in a cylindrical tube with swirling flow and stabilizing the flame position. We also attempted to stabilize the flame behavior using this system and simultaneously performed time-series PIV measurements of the flow field in the circular tube. The findings of this study are as follows: (1) We showed that under these experimental conditions, there is a strong positive correlation between the flame tip position in a circular tube with swirling flow and the integrated brightness of tracer particles. (2) Using the integrated brightness of tracer particles as an index, we determined the change in the flame tip position and the swirl vane angle according to the behavior of the premixed flame. We also showed that it is possible to keep the flame position within the circular tube. (3) While operating the flame position stabilization system, we simultaneously measured the flow characteristics near the flame tip using time-series PIV measurements. From this, it is considered that when the swirl vane angle is changed in the positive direction, the swirl strength increases, and a reverse flow region is formed. It was then confirmed that the flame propagates upstream along the formed reverse flow region.