Experimental study on pressure evolution of detonation waves penetrating into water

Abstract

Propagation of detonation waves crossing the gas–liquid interface is a basic phenomenon worth studying for underwater detonation engines. In this work, the pressure evolution of detonation waves penetrating into water is theoretically and experimentally investigated. The one-dimensional shock wave theory is adopted to solve the pressure–velocity relations of the reflected and transmitted shock wave in different mediums. Experiments under different filling pressure are performed based on a two-phase shock tube system. Theoretical results show that the range of pressure rise ratios between the detonation and transmitted wave is 2.40–2.50. Its trend is determined by the total atoms number of fuel under low filling pressure, but dominated by the ratio of C/H atoms under high filling pressure. Experimental results demonstrate that pressure rise ratios are in good agreement with the theoretical values. There are similar attenuation laws (decay to 50% in 0.3 ms) for subsequent pressure development after those two waves. Under the interface effect, the transmitted wave is stretched and the pressure zone becomes wider. The difference of acoustic impedance between two phases leads to wave property changes at the interface and exit. These changes result in the reciprocating cavitation zones and reformed shock waves in the water, greatly influencing the water pressure.