Effects of filling flow rate and equivalence ratio on flame acceleration in an obstacle channel

The propagation characteristics of flame in an obstructed tube are crucial to the transition from slow combustion to detonation. To explore the influence of filling flow rateand equivalence ratio on flame acceleration in a rectangular obstructed tube, ethylene was used as fuel, and air was used as oxidant. Based on high-speed schlieren technologyand chemiluminescence technology, schlieren imagesand flame chemiluminescence images with different filling flow ratesand equivalence ratios were obtained through experimental research. The experimental results show that the flame propagation in a rectangular channel with obstacles can be divided into two stages: slow accelerationand oscillating acceleration. Moderately increasing the filling flow rate will accelerate the transition from laminar flame to turbulent flame, and significantly promote the flame acceleration process. However, further increasing the filling flow rate will not continuously accelerate the flame propagation, and the maximum flame propagation speed fluctuates in the range of 650 m/s to 700 m/s. When the equivalence ratio of reactants is 1, the flame acceleration effect is obviously better than that of lean or rich conditions. As the filling flow rate increases, the effect of equivalence ratio on flame acceleration gradually weakens.