Numerical Simulation Of Influence Of Base Bleed On Increasing Range Of Projectile With Base Bleed

This paper presents numerical investigations of influence of base bleed on increasing range of base bleed projectile. The main points are as follow:(1) A model of one dimension multi-phase flow is established. By this method, the process of large caliber ballistic guns with base igniter is simulated. The numerical results are in good accordance with the experimental ones. Accurate muzzle velocity and base pressure of projectile are calculated, which supply the reliable boundary conditions for the numerical calculation of the base bleed unit interior ballistics.(2) In view of ambient influence to base bleed, base bleed unit interior ballistics model compounded with mass point trajectory equations is established. By the method, the influence of higher base pressure on base bleed grain combustion is analyzed. Influence of base bleed grain burning rate, base grain structures and size of bleeding hole on drag reduction and increasing range are investigated.(3) Integrating with results of interior and mass point trajectory model, compressible mass-averaged N-S equations governing the flow field around projectile with mass bleed at the base are used to analyze complex flow interactions between a supersonic base flow and a subsonic bleed jet, which are solved with Spalart-Allmaras model. In different ambient conditions, influence of variable injection parameters on base pressure of base bleed projectile is calculated. At last all the results are analyzed generally. This supplies more particular theoretical evidences and guiding principles for designing base grain and for the optimum condition of minimum base drag and maximum range.