Experimental study on the transmission characteristics of near-field detonation noise into water

Abstract

To study the transmission characteristics of near-field detonation noise into water, the detonation noise transmission system is built on a laboratory-scale water tank using a detonation tube with a diameter of 30 mm. The interaction of the detonation gas jet with the air–water interface, the development of the cavity, and the growth of the liquid column are experimentally observed by a high-speed camera. The spectral distribution characteristics of detonation noise above and below the interface are recorded by a microphone, a hydrophone, and an underwater blast sensor. Analysis of the experimental images shows that the size of the cavity increases with increasing filling pressure and decreases with increasing nozzle height. By normalizing the evolution time of the cavity with the cavity lifetime, it is concluded that the time for the cavity to develop to the deepest is about 0.27, independent of the filling pressure. The pressure field data analysis results show that the main frequencies of the detonation sound waves are 100 and 400 Hz, and the frequency distribution has nothing to do with the filling pressure. Through the defined acoustic wave energy transmission coefficient, it is demonstrated that the detonation acoustic wave transmission coefficient decreases with the increase in the frequency, and the shock wave transmission coefficient decreases with the increase in the angle.