Multidimensional Interior Ballistic Two-Phase Flow and the Chambrage Problem

Abstract

The effect of the chamber geometry of tube weapons on the performance and on the interior ballistic two-phase flow is investigated by applying the two-dimensional axisymmetric model of interior ballistics (AMI). The axisymmetric formulation in AMI has been modified such that arbitrary chamber shapes can be considered without any simplifying assumptions. The numerical results for large caliber systems show interesting flow patterns caused by the axial changes in cross section, e.g., by the transition cone or the ignitor geometry. The numerical procedure is explained. Computational results emphasize the differences between a constant-diameter chamber-bore configuration and a configuration with chambrage, i.e., with nonconstant diameter. Nomenclature A - cross section of the chamber or tube of a gun g = determinant of the Jacobian mc - initial propellant mass mp = projectile mass p = volume-averaged mean gas pressure pp =gas pressure at the projectile base Q =gas production rate per time and volume unit by propellant and ignitor s = distance between breech and projectile base s = projectile velocity «,v = axial and radial velocity components in the physical space x,y = axial and radial coordinates in the physical space a. = porosity, ratio of the gas volume to the total volume p =gas density £, t = Cartesian coordinates in the computational space