Two-Phase Viscous Flow Modeling of Interior Ballistics, Algorithm, and Numerical Predictions for an Idealized Lagrange gun
ARMY BALLISTIC RESEARCH LAB ABERDEEN PROVING GROUND MD
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A new state of the art algorithm, ALPHA, for the simulation of the multi- phase, multidimensional, unsteady, compressible, viscous, non-reactive, interior ballistics flow in a gun tube behind an accelerating projectile is described. The paper contains discussions of the physical processes in a real gun environment, of the mathematical model of these phenomena, and of the numerical technique for solving the equations. The algorithm allows the inclusion of several submodels, such as, heat transfer and turbulence. This permits the determination of the effects of these submodels on the flow. Numerical results of an idealized, one-phase ballistic cycle are given. Some of the significant results include the existence of a concentrated region of high temperature near the juncture of the projectile base and tube wall, the increase of the displacement thickness by a factor of at least three over most of the tubes length when turbulence effects are included, and the degradation of the projectile velocity by approximately ten percent under an isothermal cold wall condition.