CFD‐DEM Simulation and Experimental Study on Microchannel Seepage of HTPB Ternary Propellant Slurry

Liquid–solid flow plays a dominant role in the mixing and pouring of hydroxyl‐terminated polybutadiene (HTPB) propellants and has been modeled using various approaches. However, predicting solid flow patterns and particle interactions with continuum‐based models remains challenging. In this study, the computational fluid dynamics–discrete element method approach was employed to investigate liquid–solid flow during percolation of slurry in microchannels. The results revealed particle segregation during the slurry percolation process and showed that the microchannel width influenced the solid flow patterns significantly. The mechanisms by which coarse and fine particles are influenced by the fluid differ, leading to variations in volume fraction within the microchannels. By employing a particle staining and grouping method and investigating porosity and particle coordination number, a better understanding of the liquid–solid flow mechanism was achieved. The presence of particle segregation was confirmed by scanning electron microscopy, Fourier transform infrared spectroscopy, and differential scanning calorimetry tests on the thin film obtained from slurry curing in the microchannel. Sensitivity test results demonstrated that the slurry in the 0.3‐mm microchannel had high safety performance, ensuring intrinsic safety during propellant manufacturing. The results provide significant engineering insights into the design of core molds and safety assessment of the charging process.