Investigation on cavitation phenomena and load characteristics of fixed square plates subjected to near-field underwater explosion

The cavitation phenomenon caused by near-field underwater explosion imposes a secondary loading on ship structures. Studying the cavitation effects of plates during underwater explosions has implications for ship protection since plate is a typical structure of ships. This paper experimentally investigated the behavior of fixed square plates subjected to near-field underwater explosions. Experimental results indicated that cavitation existed in both shockwave and bubble pulsation stages; and the cavitation closure load at bubble pulsation stage was measured. To further investigate the cavitation phenomenon and the load characteristics at the bubble pulsation stage, finite element models were developed. The numerical results show that cavitation will increase the bubble load impulse by 47 % under specific conditions. These models were then used to investigate the influence of the stand-off distance and charge weight on cavitation area and load characteristics. An empirical formula was finally proposed to predict the coupled impulse of cavitation closure, bubble pulsation and water jet. This research has practical guidelines for the protection design of ship structures.