Experimental study of rheological properties of solid propellant slurry at low‐shear rate and numerical simulation

The steady state rheological properties of a three‐component hydroxyl‐terminated polybutadiene binder (HTPB) solid propellant slurry at low shear rate were investigated using a rotational rheometer. The data were analyzed and the rheological characteristics of the slurry were determined. The effect of shear rate on apparent viscosity and shear stress as well as the viscosity–time effect of the slurry were also analyzed. Herschel–Bulkley (H‐B) model was applied for the simulation of the flow process of a two‐dimensional container using CFD Ansys‐polyflow software. Experimental results showed that solid propellant slurry had yield pseudoplasticity. Yield characteristics were determined based on the fact that when shear stress was greater than yield stress, the slurry began to flow and the relationship between shear stress and shear rate obeyed power law function. Simulation results further verified the correctness of experimental results. As can be seen in figure, as shear rate was increased, interactions between molecules were decreased, entanglement point was gradually unraveled, the forces between molecular chains were weakened, and the resistance was lowered resulting in a decrease in viscosity. Moreover, the increase of shear rate also increased frictional heat generation between different laminar flows of the slurry and molecular kinetic energy, resulting in increases in fluidity. In addition, as the time was increased, viscosity curve tended to shift upward.