Experimental and simulation studies of flow characteristics of twin-blade vertical kneader with novel solid propellant slurry

In this study, the flow behavior of solid propellant slurries containing core–shell fuel–oxidizer composites during mixing in a twin-blade vertical kneader with two different modes was studied through rheological experiments and Computational Fluid Dynamics (CFD) simulations. The Herschel–Bulkley model was employed to fit the rheological data, indicating that the presence of Al@CL-20 and AP@Al would reduce the flow behavior index (n) by 0.31 and 0.19, respectively. Experimental kneading pressure was measured to validate the CFD model. Simulation results showed that the integrated composites significantly increased the apparent viscosity of the slurry and led to lower tangential but higher axial velocities during mixing, compared to conventional formulations. Compared to the control group, slurries containing Al@CL-20 have 66.7% and 56.3% higher peak kneading pressure under two mixing modes. The torque of both solid and hollow blades was increased by more than 30%, suggesting a notable rise in energy consumption during processing. A potential mechanism describing the variation of flow field characteristics was proposed.