Evaluating the shape and orientation effect of non-spherical charge on the pressure distribution of underwater explosion: Finite element analysis

Limited studies available are presented to investigate the shape and orientation effect of pressure distribution and peak pressure of non-spherical charge in near-field underwater explosion (UNDEX). A detailed 3-D finite element model based on arbitrary Lagrange-Euler (ALE) algorithm is used to study the near-field pressure distribution of UNDEX within infinite water field. The numerical results of the model are verified against the empirical results. The influence of the shape and orientation effect on the pressure distribution was also analyzed based on the numerical data. It is found that the model is suitable for the reproduction of the near-field shock waves for the non-spherical explosives within infinite water field. The shape and orientation effect have significant impact on the pressure distribution of near-field UNDEX. The deviation of the incipient pressure of the non-spherical charges from the constant-mass spherical charge (C0) increases with the length-to-diameter ratio increasing. Compared with the cylindrical charge (C1), the peak pressure of spherical charge continue to reduce with lower attenuation speed in the same propagation time from 0.02 ms to 0.22 ms. However, the peak pressure of cuboid charge is not monotone changing with the same propagation time. The pressure distribution and peak pressure of UNDEX have direct relation with the detonation modes, especially in the near-field region. A reference formula for the peak pressure of the non-spherical charge is also obtained to provide a reference for engineering design.