Combustion wave propagation through a bank of cross-flow cylinders

Combustion wave propagation through a bank of 12.7 mm diameter cylinders is investigated in a 76.2 mm tall, 25.4 mm wide channel using high-speed schlieren photography. Two cylinder geometries (“staggered” and “inline”) were tested with 50% channel area blockage. The staggered geometry was also tested with 67% blockage. Tests were carried out with hydrogen-air at atmospheric pressure. Flame propagation is highlighted by an initial flame acceleration phase driven by turbulent burning in the cylinder wakes. This is followed by quasi-steady flame propagation characterized by shock-flame interactions. Flame acceleration measured in the staggered and inline cylinder geometry, for the same blockage, was found to be similar despite the different flame pathways. In the fast-flame regime, the quasi-steady flame velocity was also found to be very similar. In the composition range where detonation initiation and failure was observed, often referred to as the quasi-detonation regime, the average velocity was significantly higher in the staggered cylinder geometry due to the higher frequency of detonation initiation.