Study On Granular System Dynamics Of Propellant Bed With Press And Fracture

Research on dynamic characteristics of Granular system is concerned in many fields.Under the background of launching safety of propellant charge project, movement,accumulation, press and fracture of granular system have been systemically studied.Dynamic characteristics of granular system is simulated by using the Discrete ElementMethod. In order to improve the computational efficiency, contact detection algorithm isused. Dense accumulation structure of granular system which is made up of many spheralparticles is obtained by using geometrical constructive algorithm. First, fracture model ofsingle particle is applied to granular system. Second, simulation method on granularsystem dynamics with fracture phenomenon is set up. At last, this simulation method isused to study the dynamic characteristics of granular system with fracture phenomenon ofpartial particles under ladder loads. All the results of numerical simulations aredynamically showed by the postprocessing programs which are based on OpenGL.Physical and numerical simulations which are aimed at propellant bed which is made up ofmany propellant particles with hexagonal prism shape are done, and the results of twosimulations are basically identical. The study results provide the base of theory andexperiment for propellant safety.Fracture model of propellant particle is set up, and this model is used to study the dynamiccharacteristics of propellant particle's impulsion and fracture. Dense accumulationstructure of propellant bed which is made up of many propellant particles with hexagonalprism shape is obtained by using dynamic techniques. Fracture model of propellant particleand simulation method on granular system dynamics with fracture phenomenon are appliedto simulate the press and fracture process of propellant bed. According to followingmovement and fracture of each propellant particle at typical time, the fracture degrees ofpropellant bed are obtained by statistical method.The press stress of propellant bed which is the same to real environment is obtained by thephysical simulating experiment of in-bore burning and mechanical environment ofpropellant bed. Through this stress pressing propellant bed, fracture propellant particles areobtained by the physical simulating experiment of the press and fracture of propellant bed.First, the p～t curve of fracture propellant particles is tested by using the experiment ofclosed vessel. Second, on the basis of the definition of dynamic activity of propellantparticle, the method which is used to exactly describe the initial burning surface areas of all the propellant particles is set up by introducing initial dynamic active ratio. At last, thedescribing method of the fracture degrees of propellant bed is set up.