Flow Simulation Of The Bottom Row Of The Transient Relief Process

The base bleed projectile has simple structure and high extend range rate, and has large dispersion too. One of the reasons leads to large dispersion is that, working pressure of base bleed projectile changes from high gun pressure to barometric pressure. Because of high transient, it is hard to measure. In this paper, numerical simulation of base bleed projectile that is shooting out of the gun is presented, the work presents as follows:Firstly, the calculation models of the flow field of muzzle flash and the process that projectile is shooting of muzzle are made. Simulations of two-dimensional unsteady flow field of muzzle flash and near muzzle flash of the process that the projectile is shooting out of muzzle are made. The analysis of the change of wave structure is made, and results agree well with experiment results, show that the means of numerical simulation used in this paper is feasible.Secondly, the calculation model of base bleed unite that is shooting out of gun is made. The flow fields of base bleed unite depressurization with velocity of movement or not and with burning rate or not are simulated. The influence of velocity of movement and burning rate to the flow field is analyzed.Thirdly, the calculation model of base bleed projectile that is shooting out of gun is made. Flow fields near muzzle flash during the process of base bleed projectile is shooting out of gun with burning rate or not are simulated. The flow filed is analyzed and compared with that of near muzzle flash during the projectile shooting out of gun and that of base bleed depressurization, the process of base bleed projectile is known overall.Finally, the combustion model of base bleed projectile that is shooting out of gun is made. The combustion system of BBP and gun gas are simplified and replaced by H2-CO combustion system. The combustion process is modeled by finite-rate chemistry, and the combustion mechanism consists of nine reactive species and twelve reaction steps. The change laws of flow field structure and composition profile are presented.The results of this paper provided a certain theoretical reference for the experiments and engineering applications, and make a good foundation for more in-depth study of the base bleed projectile.