Peak Pressure Variation with Grain Fracture: Using a Lumped Model for Projectile Energizing with Seven Perforation Grain

Abstract

Propellant grain geometry plays a critical role in pressure space behaviours in interior ballistics which are important for operational safety of gun barrel designs. This geometry leads to a burning surface which is tractable to mathematical models only if the grains do not fracture. Complex high fidelity models for situations when grains fracture require significant computational effort. We propose to use instead the conventional lumped model with certain normative assumptions about grain fracture. We demonstrate that with seven perforation grains of two different lengths having different loading mass fractions to mimic fracturing, we can inform design insights concerning peak pressure variation. In particular, our results suggest that hole radius and outer radius could be optimized to provide minimum peak pressure variation on account of grain fracture.