Experimental study on propagation dynamics characteristic of premixed syngas/air explosion in parallel narrow channels

Experiments of premixed syngas/air explosion in parallel narrow channels(PNCS) were carried out under the condition of equivalent ratio (phi) varying from 0.6 to 2.5 and ignition distance away from the entrance to PNCS changing from 190 mm to 590 mm. The flame propagation process, explosion pressure and temperature in PNCS were obtained. The result showed that the ignition distance had a significant effect on flame propagation in PNCS by affecting the inlet flame structure and velocity. The equivalent ratio had a significant effect on the explosion dynamics propagation in PNCS, which changed not only the inlet flame structure and velocity, but also explosion reactive rate in PNCS. The flame in the PNCS inherited the characteristic of inlet flame at the entrance to PNCS and developed further into a multi-headed tulip shape at phi = 1.2, into a tulip shape at phi = 1.0 and 1.5, and into a finger-shaped flame at phi = 0.8 and 2.0. While the flame quenched inside the parallel narrow channels at lower (phi = 0.6) and higher (phi = 2.5) equivalent ratios. After the flame passed through the PNCS, the flame came back into and leaved from the PNCS several times. The flame velocity, pressure maximum (Pmax) and temperature maximum (Tmax) in PNCS reached a maximum at ignition distance S11 (490 mm away from the entrance to the PNCS) for phi = 1.2 due to the greatest inlet flame velocity at S11. As the equivalent ratio increased, the pressure and temperature increased and then decreased which reached the maximum at phi = 1.2 because of the chemical reaction rate of syngas being the fastest at phi = 1.2. The pressure and temperature were greatly affected by the flame back and forth entry the PNCS from the buffer pipe. The front -end pressure was about half of the back -end pressure in PNCS. The temperature had more than one peak in the PNCS. The experimental results were important for insight into the kinetic mechanism of flame propagation in parallel narrow channels.