Axial acoustic signature of dual detonation tubes

Abstract

The axial acoustic characteristics of detonation sound waves generated by single and dual detonation tubes, utilizing methane as fuel and oxygen as oxidizers, are experimentally investigated. Various acoustic parameters are analyzed, including the effective sound pressure level, A duration, and energy characteristics. By the A duration, we mean the time when the sound pressure ascends to a significant maximum and then swiftly descends to the ambient pressure. Experimental results reveal that the decay rate of the effective sound pressure level gradually decreases with increasing distance, with ground reflection prolonging the A duration. The energy of the detonation sound wave is primarily concentrated in the low frequency, and the proportion of low-frequency energy increases with distance. For the dual detonation tubes, the detonation sound wave exhibits a higher effective sound pressure level and A duration compared to the single detonation tube. Although the energy proportion and wave structures of detonation sound waves generated by the dual detonation tubes are similar to those of the single detonation tube, the high-frequency energy experiences greater gain. The effective sound pressure level of the dual detonation tubes increases with the separation distance. Altering the ignition interval can transfer energy to lower frequencies, albeit slightly reducing the effective sound pressure level. These findings highlight the significant impact of the spacing between dual detonation tubes on the effective sound pressure level, and the potential for changing the ignition interval to modify the energy characteristics of the detonation sound wave.