Research on bubble pulsation and jet loading characteristics during a near-field underwater explosion

To deeply study the bubble jet phenomenon occurring during the near-field underwater explosion, this study performed an underwater explosion test of small equivalent TNT exploding at the bottom of a clamped square plate. The load time history curve of the bubble jet was successfully measured by the method employing an array wall pressure sensor. The experimental results show that the peak value of the bubble pulsation pressure at the bottom center of the clamped square plate is not significantly different from the peak value of the jet pressure. However, the duration of the jet pressure is 21.36 times that of the bubble pulsation pressure. The bubble pulsation pressure and its duration slightly attenuate, while the jet pressure and its duration attenuate faster with the increasing distance from the sensor to the center, indicating a quite concentrated range of jet load. Further, the numerical simulation of the whole process from the explosion to the bubble jet formation was performed via the Abaqus software. The bubble evolution process and the bubble jet load time history curve obtained by the simulation are consistent with the experimental results. Finally, the distribution law of the specific impulse of the bubble jet, the evolution law of the bubble jet shape, and the change law of the head speed of the bubble jet during the near-field underwater explosion bubble pulsation process are obtained through numerical simulation. This work can provide a basis for the destructive strike of surface ship structures using bubble jets formed by a near-field underwater explosion.