Optimal design of guns’ propellant charges

A method to design guns’ solid propellant charges is developed. Contrarily to existing charges, based on granular propellants, the present one considers large multiperforated monoliths. With granular propellants, about half of the combustion chamber volume is empty. In the present approach, the aim is to fill nearly the entire volume, resulting in heavier propellant charges masses, without exceeding guns’ maximum admissible pressure. Consequently, guns performances are expected to be significantly enhanced. The method uses an enhanced zero-dimensional (0D) two-phase flow model which accounts for the phase velocities and drag effects between phases. Consequently, the kinetic energies of the phases are not neglected. The first step consists in a specific use of the 0D model to determine the optimal specific interfacial area during propellant burning. The optimal interfacial area maintains the pressure at the maximum admissible level in the gun combustion chamber until the end of the combustion, resulting in an enhanced muzzle velocity. The second step is decoupled from the first one. The aim is to determine the design of realistic charges to reproduce, as accurately as possible, the optimal interfacial area. The optimized propellant charge consists of fine spherical grains and large monoliths, which are multiperforated cylinders with a diameter equal to the gun caliber. The geometrical parameters of the grains and monoliths are determined to fit the optimal specific interfacial area. Determination of these parameters is simple and accounts for practical limitations in manufacturing. The resulting optimized charges demonstrate significant performance enhancement compared to conventional multiperforated gun powders.