Effects of ignition time differences and array parameters on acoustic characteristics of multi-detonation-tube arrays

This paper explores the acoustic characteristics of detonation sound waves (DSWs) generated by multiple detonation tubes through experiments considering various ignition time differences (ITDs), numbers of tubes, and tube spacings. The experiments use methane as the fuel and oxygen as the oxidant and measure the peak sound pressure, effective sound pressure level, and frequency spectrum. The experimental data show that the pressure level of DSWs can be effectively improved by increasing the number of detonation tubes. However, in the case of simultaneous ignition or small ITDs, increasing the number of tubes does not significantly change the wave structure of the DSW. In the case of multiple detonation tubes, there is a marked decline in the peak pressure and effective sound pressure level as the ITD increases. These energy attenuations are mainly concentrated in the low-frequency region below 1000 Hz and gradually shift to lower frequencies with increasing ITD. Moreover, changes in the ITD modify the structure of the DSWs, with increases in the ITD extending the duration of the positive-pressure region, but paradoxically reducing the energy proportion. Under asynchronous ignition conditions, the peak pressure and effective sound pressure level can be enhanced by increasing the tube spacing so as to reduce the interference of the central jet. These changes indicate that the ITD has a relatively significant negative impact on the pressure characteristics of DSWs and regulates the associated energy distribution.