Detonation wave propagation through a single orifice plate in a circular tube

Detonation behavior associated with the propagation of a detonation wave through an orifice plate located within a circular tube is investigated. The tube and orifice diameter used in the study are 27.3 cm and 10 cm, respectively The test gas used is hydrogen-air at 1 atmosphere and at various initial temperatures up to 650 K. Immediately after the orifice, the detonation wave decouples and either fails or reinitiates. The reinitiation process is characterized by either spontaneous initiation, initiation due to shock reflection, or deflagration-to-detonation transition (DDT). In the case of DDT, transition is preceded by the degeneration of the decoupled detonation wave to a velocity consistent with a CJ deflagration. Delineation between these various propagation regimes could not be correlated with the detonation cell size, lambda, and orifice diameter, d. The data, although limited, demonstrate for the first time that the d(c)/lambda = 13 critical tube criterion obtained at room temperature may not apply at elevated temperature conditions. The evidence for this is data obtained at 500 K that shows no detonation transmission for 30% hydrogen in air that corresponds to d/lambda = 16.7. The tests also indicate that a simple d/lambda correlation cannot be used to determine when reinitiation due to shock reflection is possible. For example, at 650 K detonation wave failure was observed for d/lambda < 7.4, and at 300 K failure was observed for d/lambda < 11.