Research On Near-field Shock Wave Characteristics Of Underwater Explosion Of Aluminum-containing Explosives

Near-field underwater explosions can generate strong intermittent shock waves,causing serious local damage to ship structures.Compared to ordinary charges,aluminum-containing explosives can prolong the underwater explosion time and expand the scope of action.Therefore,it is of great significance to study pressure characteristics of near-field underwater explosion for aluminum-containing explosives and its damage to structures.With the rapid development of computer technology,it has become a trend to combine numerical simulation with experimental techniques to investigate the near-field underwater explosion.In this paper,an Eluer method was used to establish the near-field underwater explosion model.The shock wave loading characteristics and its damage characteristics of underwater explosions of TNT charges and aluminum charges are compared and the effectiveness of the numerical model is validated by experiments.The purpose of this paper is to provide reference for the prediction and structural response of near-field underwater explosion shock wave loading for aluminum-containing charges.First of all,researches of underwater explosion of aluminum-containing explosives in recent years is summarized.Then,the representative works of detonation models of aluminumcontaining explosives,shock wave loads in near-field underwater explosions,and structural responses are reviewed.After that,based on the principle of energy equivalence,an empirical formula for the peak pressure of the near-field shock wave of aluminum-containing explosives is deduced.The validity of the empirical formula is proved through the comparison with the experimental data.In order to study the near-field underwater explosion of aluminum-containing explosives,an experiment study was carried out to investigate the peak pressure of near-field shock waves,and a dedicated sensor for near-field waters was designed.The PVDF sensor was used to capture and record the peak pressure of the near-field shock wave of a 10-fold radius.The operability of the shock wave pressure can still be tested under near-field conditions,and the different reaction mechanisms between the aluminum charge and the TNT charge under test conditions are compared and analyzed.The dynamic finite element program AUTODYN is used to simulate the underwater explosive process of a typical aluminum explosive in the free-field.Firstly,an underwater explosion model of free-field underwater explosion is established.The effect of the state equation and the grid size on the numerical simulation results is discussed.The results show that the polynomial equation of state and small grid size can improve the precision of numerical simulation.After that,the load characteristics of the underwater explosive shock wave of aluminum explosives and the effect of aluminum content are studied.The comparison results between the numerical and experimental methods show that the secondary heat release of aluminum powder has a supporting effect on the shock wave energy.On this basis,the nearfield underwater explosion model of aluminum explosives was further established.The shock wave loading characteristics of the near-field underwater explosion of TNT and aluminumcontaining explosives and their dynamic response to the circular plate are compared and analyzed.The failure of circular plates subjected to near-field underwater explosion of different explosives was obtained.The form provides a reference for the formula design of underwater weapons charges and the anti-knock performance of ships.