Energy Release Law And Assessment On Blast Wave Power Of Aluminized Explosives

Aluminized explosive is one of the typical non-ideal explosives,whose detonation behaviors can't be described by the well-known Chapman-Jouget(CJ)model or the Zeldovich-Nwuma-Doering(ZND)model.During the detonation process of an aluminized explosive,the secondary reaction of aluminum powder,which releases energy for a longer time behind the CJ plane,makes the detonation products expansion non-isentropic,and introduces extensive difficulties into its thermodynamic study.However,the detonation products expansion is essential to the assessment of the capacity of doing work by an explosive,thus the dissertation aims to describe the expansion process for detonation products of an aluminized explosive,assess the capacity of doing work by the detonation products and the power of its air blast wave in the far field.Firstly,the secondary reaction of the aluminum powder contained in an aluminized explosive is investigated,from which,the energy lose resulted from reduce of the total quantity of the gaseous products is demonstrated.Moreover,taking the energy lose into account,the existing improved JWL equation of state(EOS)for detonation products of aluminized explosive is modified.Using the new modified JWL EOS for detonation products of aluminized explosive,together with the Miller reaction rate,the metal plate acceleration tests for the aluminized explosives are investigated by numerical simulation.The secondary reaction energy release model and the new modified JWL EOS for an aluminized explosive is demonstrated.Based on the energy conservation law,this dissertation proposed a theoretical approach which can determine the adjustable parameters in the JWL EOS for the detonation products of LiF-contained explosive,and its accuracy is demonstrated by the metal plate acceleration test;Futhermore,a one-dimensional spherical symmetric combustion model for aluminum particle in the explosive environment is established,which based on the physical and chemical parameters of the aluminum and the detonation products,and a theoretical reaction rate for the secondary reaction of aluminum powder contained in the aluminized explosives is developed.Considering the similarity of the detonation stages for aluminized explosive and LiF-contained explosive and the secondary reaction energy release model for an aluminized explosive,a theoretical approach which can predict the expansion process for the detonation products of aluminized explosive is developed in this dissertation.By conducting the explosion experiments in the air for aluminized explosives,the overpressure of the air blast wave for the aluminized explosives with different composition are investigated.Their TNT equivalent mass are obtained and the experimental data is practically meaningful to the composition research for aluminized explosives.Based on the secondary reaction energy release model for aluminized explosive,the parameters of the initial air shock wave for aluminized explosives are obtained by numerical calculation.It is found that the forming location of the initial air shock wave for aluminized explosive is more far away from the explosion center,and doesn't obey the similarity law,which can explain the experimental phenomenon that the air blast wave pressure of aluminized explosive decreases more slowly than that of ideal explosive.Through dimensional analysis,a semi-empirical formula is proposed to predict the peak overpressure of air shock wave for aluminized explosives and other non-ideal explosives.This method is more appropriate than the TNT equivalent mass method,and can reflect the propagation law of the air shock wave for the aluminized explosive well.With the new modified JWL EOS for detonation products of aluminized explosive and the theoretical reaction rate of aluminum powder implemented into the calculation program with finite difference method for explosive shock wave,the explosion in the air for aluminized explosives are simulated.The accuracy of the theoretical reaction rate for aluminum powder is demonstrated by the correspondence of the numerical simulation results and the test results.Futhermore,the influence of the secondary reaction on the air blast wave is investigated by numerical simulation.Moreover,the influence of the charge dimmeter,the aluminum particle diameter and the content of the aluminum powder on the detonation products pressure and the over-pressure of the air blast wave are also investigated.It is indicated that,the content increase of the aluminum powder can greatly enhance the power of the air blast wave of aluminized explosive,and the energy efficiency of the secondary reaction for the smaller aluminum powder is higher.