Study On Mechanism Of Burn Rate Enhancement Of Solid Propellant With Plasma And Modeling Of Multidimensional Multiphase Flow

With the objective to investigate the mechanism of electrothermal chemical launch, this paper lay emphasis on burn rate enhancement effect of solid propellant under the action of electrothermal plasma and multi-dimensional multiphase interior ballistic problem in electrothermal chemical gun.The main points are as follows:(1) A modified closed bomb is used to study the ignition and burn rate enhancement characteristic of several kinds of propellants under the action of plasma. Experimental results show, the ignition and combustion process of propellant can be effectively modulated by controlling the electric discharge behavior of pulsed power supply. Plasma can greatly shorten the ignition delay and markedly increase propellant burn rate.(2) In closed bomb experiments, we find two kinds of burn rate enhancement modes for different kinds of propellant. The two modes are burn rate enhancement during the electric discharge and burn rate enhancement after the discharge. The post-discharge burn rate enhancement can also be divided into two modes, increasing mode and decreasing mode. These findings provide the theoretical basis of achieving plateau effect of bore pressure, increasing ballistic efficiency and muzzle velocity.(3) Effort is made to elucidate the mechanism of propellant burn rate enhancement phenomena by the action of plasma. The different ways of action of convective and radiative heat transfer on surface layer and inner layer combustion behavior are presented. The influence of graphite layer, coating and passivation layer on propellant combustion behavior is also analyzed.(4) By means of modifying the exponential-form burn rate law in common use, a burn rate law related to both temperature and pressure is presented, which more accurately describes the burn rate law of propellant under the action of plasma.(5) Transient multi-dimensional multiphase flow model is adopted to investigate electrothermal chemical launch process. Many parameters of the electrothermal chemical launch process are calculated in the model. And calculated breech pressure, muzzle velocity and discharge parameters agree with experimental results.(6) Ballistic parameter consistency in the situation of hypervelocity (>2200m/s) launch is achieved with small caliber electrothermal chemical launch device. The velocity and pressure differences of a group of several shots are small.(7) The influence of high loading density and plasma generator on performance of electrothermal chemical launch is also investigated in the paper. This study points out the way to further improve the efficiency of electrothermal chemical launch.