Influence of inclination parameters for axial‒radial combined structure on silicon nitride particles mixing prepared by dry method

To solve the problems of poor mixing effect and poor sphericity for the silicon nitride particles in the dry granulation chamber, the influence of the inclination parameters for the open turbine typed axial‒radial combined structure on the mixing effect of silicon nitride particles prepared by dry method was studied. The mathematical model of Eulerian‒Eulerian gas‒solid two phase flow was established, and the physical model of the axial‒diameter combined structure granulation chamber was simplified. The computational fluid dynamics (CFD) method was used to analyze the volume distribution and velocity field of silicon nitride particles in granulation chamber in the axial structure under the different inclined angles. The sphericity of silicon nitride particles was tested by experiments, and the accuracy of numerical simulation results was verified. The numerical analysis results show that, when the inclination angle is 45°, the volume fraction of silicon nitride particles is 0.3~0.7 (accounting for 28%), showing the better circulating fluidity and the best mixing effect, compared with the inclination angle of 30° and 60°. The experimental results show that, the best average sphericity of the silicon nitride particles is 0.72 when the inclination angle of the axis‒diameter combined structure is 45°, which can effectively improve the mixing effect of silicon nitride particles.