Experimental study on the combustion-induced rapid phase transition of syngas/air mixtures under different conditions

Abstract In this work, the explosion pressure oscillation characteristics of premixed syngas/air mixtures were studied experimentally in the duct with different hydrogen concentrations and opening ratios. The results indicate that the overpressure changes as the hydrogen fraction and opening ratio varies, and the venting can mitigate the phenomenon of CRPT by increasing the opening ratio of the duct. With the increase of hydrogen volume fraction, from 10% to 50%, the rise rate of explosion overpressure increases rapidly, the maximum overpressure increases and the shortening time of reaching the maximum pressure decreases gradually. With the opening ratio increasing, the resistance, the turbulence and the pressure peak decrease gradually. Moreover, if the ratio is greater than 0.5, it has a small effect on the pressure peak; when the ratio is less than 0.5, it has a significant effect on the pressure peak. Through analyzing the dominant periods and average amplitudes of the oscillations, it can be found that the syngas combustion has an obvious combustion-induced rapid phase transition phenomenon in the opening duct. The decrement of the opening ratio and the increment of the hydrogen concentration contribute the average amplitude to increasing.