Selection of Die Shape for Manufacturing of Energetic Materials by CFD Modeling

The first principle of numerical modeling of die extrusion of energetic materials is carried out to reduce the needed pressure gradient along the die. The proposed new die design with a converging shape outlet appears to have a smaller pressure drop compared to the current U.S. Army Armament Research, Development and Engineering Center (ARDEC) die shape. The optimal shape was obtained by finite-volume fluid dynamics computations through a range of die designs. The presented computations have been performed for a 3D die equipped with different outflow pipes. The features of the flow field are obtained for the non-Newtonian fluid through the apparatus. The change of fluid model from Newtonian to non-Newtonian complying power law does not make a considerable change in velocity profile at outlets for the same mass flow rate. Nevertheless, there is a substantial increase in the pressure gradient needed to transport the fluid through the die. For the new proposed die design, apparent viscosity steadily drops along the centerline of the outlet. As the viscosity magnitude determines the needed pressure drop, the new die design with a converging shape outlet has a substantially smaller pressure drop compared to the current die.