Effects of Equivalent Ratio on Flame Acceleration in Channels with Obstacles of Different Shapes
This paper investigates the flame acceleration process of premixed hydrogen/air with dif-ferent equivalence ratios in obstacle channels by high-speed schlieren photography technique.There are three types of obstacle shapes,including triangle,fully-cut semicircle and semicircle.The results indicate that the equivalence ratio changes the flame propagation speed and evolution process inside the channel by affecting flame instabilities and laminar flame speed.When the equivalence ratio(φ)is 1.5,the flame propagates at the fastest speed.The shape of obstacles has a significant impact on flame acceleration.Obstacles with sharp structures are conductive to the stretching and frag-mentation of flame,promoting flame turbulization.Under extremely rich fuel conditions(φ=3),the evolution of the flame front is more stable,and sharp fully-cut semicircular obstacles have a more significant effect on flame turbulization,enhancing the acceleration.The flame transition in the semicircular obstacle channel is smooth and spreads slowest.This study can provide experimental support for explosion safety and burner design.
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