Effect of obstacle position and equivalence ratio on syngas explosion characteristics

An experimental study of premixed syngas/air flame explosive characteristics in an obstacle pipe is introduced. Square obstacles with a blocking rate of 0.5 are installed at varying positions from the ignition end inside a closed pipe to conduct syngas-air explosion dynamics experiment with varying equivalence ratios (phi) and obstacle positions (OP). Results show that compared to OP = 150 mm, the tulip flame will form at OP = 450 mm and OP = 750 mm. The distribution of flame front velocity and overpressure have same trend in the process of flame oscillation. Nevertheless, the overpressure curve will produce oscillation when the flame propagates out of the pipe at OP = 450 mm. As the increase of OP, the maximum flame front velocity first increases and then decreases and the maximum overpressure decreases gradually. Both the maximum flame front velocity and maximum overpressure first increase then decrease with phi, reaching the maximum at phi = 1.4. This research can provide some suggestions when syngas-air fuels are applied in the presence of obstacles.