Numerical Simulation On The Rheological Parameter Variation And Mixing Ability Of Single-screw Extrusion Process Of Propellant

Solid propellant has played a significant role in national defense industry, and single-screw extrusion is widely used in production of solid propellant. While, the extrusion process has the characteristics of multiple accidents, complicated rheological parameters and difficult measurement of real-time conditions, therefore, the process details can be reproduced by simulation conveniently and intuitively. In this paper, the POLYFLOW simulation platform was used to model and analyze the single-screw extrusion process of propellant under different work conditions and the mixing ability through the application of Finite Element Analysis on the extrusion process of plastics.In the steady-state problem section, parameters of velocity field, viscosity,pressure field and temperature field were studied in geometric distribution and change regulation. It turned out that close to the screw edge, viscosity was low, shear rate was high, and the phenomenon of viscous heating was obvious. It was easier to form a "hot spot" near this part, because of the accumulation of heat. And the pressure peak was also at this position, which should be paid more attention to. Secondly, in the time-dependent problem section, the results showed that there were elevated signs both in pressure and temperature fields along with the time, and the rising ranges decreased. So the start of operation should be focused on. Single factor method was applied in both sections to discover the effect of rotation in varied parameters. It was found out that the rotation speed had a significantly positive correlation with different parameters, so the increase of production and pursuit of interests should be under the precondition of guarantee the safety.Mixing ability was studied from residence time distribution, mixing index and mixing statistical analysis in the mixing function section. The results showed that the geometry of the screw channel had greater effect on the mixing ability of the extrusion. And the probability function of the mixing index was independent of time, however, the maximum reached by each particle increases with time, so the maximum of mixing index was a function of time.The results of this paper were feasible for process control of single-screw extrusion process of propellant, the coordination of safety and profit, and the improvement of design.