Numerical Study of Initial Pressure in Unsteady Flow Field with Base Bleed

Abstract

When the base bleed projectile leaves muzzle, the combustion chambers will undergo a strong unsteady process, which will strongly disturb the tail flow field and affect the drag reduction efficiency. In order to study the effect of the initial pressure on the drag reduction of the base bleed projectile with annular jet during the transient depressurization process, the improved advection upstream splitting method (AUSM+) scheme and k-ω shear stress transport (SST) turbulence model were used to solve two-dimensional axisymmetric Navier-Stokes equations. The development of the flow field at the bottom of the annular jet model during transient depressurization is studied numerically. The characteristic parameters and drag reduction characteristics of the bottom flow field of the annular jet model at different initial pressures are compared and analyzed. The results show that initial pressure has little effect on the flow field structure, and the influence on the flow field characteristic parameters is mainly in 0.1ms≤t≤1.5ms. The flow field characteristic parameters of the final depressurization process are unaffected. In the process of transient depressurization, as the initial pressure increasing, the bottom flow field spend more time to be stable, the average temperature of bottom decreases, but the average pressure of bottom increases, and drag reduction effect is better.