TWO-PHASE FLOW IN GUN BARREL

Slobodan Jaramaz

Dejan Micković

Abstract

The subject of this information is theoretical modelling of the two-phase flow of black powder and its combustion products in the igniter, as well as the two-phase flow of solid granular propellant and its products of combustion in the gun barrel during the interior ballistic cycle. Starting from the conservation equations of mass, momentum and energy for gaseous and solid phase in the local-instantaneous form, the corresponding macroscopic balance equations of mass, momentum and energy are defined for both phases by the averaging procedure, where the interphase exchange of mass, momentum and energy are characterised in separate terms. By incorporating appropriate source terms, the macroscopic equations are completed for the cases of two-phase flow in the igniter and the two-phase flow in the propellant charge during base ignition or during ignition by igniter. The necessary constitutive laws for the two-phase flow in the igniter and the two-phase flow in the propellant chamber and gun barrel are analysed. The appropriate relations are adopted or developed for the constitutive laws determination. Initial and boundary conditions for the two-phase flow in the igniter and for the two-phase flow in the propellant chamber and gun barrel are defined. The presented theoretical approach enables, not only a choice of an optimum igniter and a complete optimisation of propellant charge ignition, but more successful solutions of many interior ballistic problems as well.

Key words: ballistics, interior ballistics, propellant charge, ignition, propellant combustion, flamespreading, two-phase flow, conservation equations, gun barrel