To simulate the flow behaviors of gun propellants in extrusion processing assisted with supercritical carbon dioxide (SC-CO2), a numerical software Polyflow was applied to investigate the pressure, viscosity and velocity distributions of CA/SC-CO2 mixture under various processing conditions. The results demonstrate that the highest pressure of the die appears at the entrance of the die, and the pressure decreases smoothly to the atmospheric pressure. The injection of SC-CO2 reduces the viscosity and the pressure of the flow significantly. Increasing the length of the die raises the inlet pressure, but it has few effects on the viscosity distribution. Increasing both the processing temperature and the solvent content can decrease the pressure in the die. The inlet pressure reduces by about 30%, when the temperature rises from 45°C (9.66 MPa) to 55°C (6.77MPa). Besides, too high solvent content leads to the structural damage of the products. The numerical simulation of CA/CO2 mixture provides the fundamental and significant experimental data for the extrusion of gun propellants assisted with SC-CO2.
gun propellant, Polyflow, SC-CO2, extrusion, flow behaviors