Abstract
Extrusion-based 3D printing holds great potential for manufacturing solid propellants. Among the various methods, screw- and plunger-based extrusion are the most frequently reported techniques for propellant 3D printing, each employing different extrusion mechanisms. This paper compares the flow characteristics of these two methods through a combination of simulations and experiments. Simulation results reveal that propellant slurry in a plunger extrusion device exhibits relatively stable flow characteristics, especially near the nozzle outlet, with high flow velocity, high shear rate, and low-pressure distribution. Compared to the screw-based device, the plunger extrusion achieves a more uniform outlet velocity. In contrast, the screw extrusion device produces more complex rheological behavior, with backflow observed in the gap between the screw and the extrusion channel wall. However, the average pressure in the flow channel for screw extrusion (3885.11 Pa) is notably lower than that of plunger extrusion (7292.92 Pa). Experimental results indicate that the printing quality of plunger extrusion is comparable to that of screw extrusion. These findings provide valuable insights into advancing extrusion-based 3D-printing processes for solid propellants.