Study on the characteristics of initial shock waves generated by cylindrical charge for underwater explosion

Abstract

In order to provide a theoretical basis for studying the shock wave propagation and evolution generated by cylindrical charge of near-field underwater explosion, the characteristics of initial shock waves generated by cylindrical charge are studied. First, a new theoretical model for initial shock waves is proposed by the polar curve method. Based on the theoretical model and the simulated results, the influences of incident angle, length-to-diameter ratio and type of charge on the initial shock waves are analysed. Then the experiments of underwater explosion load tests are carried out to verify the theoretical and simulation results. Finally some instructive conclusions are drawn: i) The two-dimensional theoretical model can calculate the initial underwater shock wave pressure and its direction of cylindrical charge through detonation velocity, detonation pressure, explosive density and incident angle, which is provides a theoretical basic for studying the shock wave propagation and evolution studies. By comparing the theoretical results with the numerical results verified by experiments, the maximum error is not more than 9.93%. ii) Increasing the incident angle α 0 will reduce the initial shock wave pressure of cylindrical charge and make its direction deflect towards the material interface. When the incident angle α 0 is in the range of 0 - 10°, increasing the incident angle makes the initial shock wave pressure decrease rapidly as a power function. With the increasing of the incident angle, the attenuation rate of the initial shock wave firstly decreases and then increases when the incident angle α 0 is in the range of 10 - 72°. This phenomenon explains the reason that the axial and radial initial shock wave pressures are much higher than those in other directions after the central initiation of cylindrical charge. iii) According to the geometric relationship, the length-to-diameter ratio of the charge will limit the range of the incident angle. The length-to-diameter ratio will affect the initial shock wave pressure at the same initiation time. The pressure decreases with the increase of the length-to-diameter ratio when the initial shock wave is formed on the cylindrical surface of the charge.