Effect of blade angle and particle size on powder mixing performance in a rectangular box

This study focuses on the understanding of flow over a single blade and its impact on powder mixing. The Discrete or Distinct Element Method (DEM) is used and the flow of a single blade through a bed of a binary particle mixture is studied. Mixing performance with respect to a blade-rake angle and particle size is investigated using the Modified Generalized Mean Mixing Index (MGMMI) and the maximum mean instantaneous velocities. A wide range of angles and different loading scenarios of the binary particle mixture were studied. Velocity profiles for all these cases were computed, as well as the forces on particles and the blade. The results showed an inverse relation between the interparticle force and blade-rake angle. Systems with a higher number of larger particles experienced a higher interparticle force. Similar results were obtained for the blade force. The results for mixing efficiency showed that if the smaller particles are placed at the top this leads to a higher mixing performance. The mixing performance was highest for blade-rake angles that offered a maximal surface area or maximal resistance to the flow of particles, which occurred for blade-rake angles from 70° to 90°.

Impact of blade-rake angles and particle size on mixing performance (MGMMI) Mixing performance of a 2-D single blade is studied as a function of blade angle and particle size. A wide range of angles and loading scenarios of a binary particle mixture were studied. Velocity profiles for all these cases were computed, as well as the forces on the particles and the blade.Impact of blade-rake angles and particle size on mixing performance (MGMMI).Figure optionsDownload as PowerPoint slideResearch highlights
► We study granular flows over a single blade.
► Blade forces varied inversely with respect to the blade-rake angle.
► At highly acute blade angles of < 60° locking of the mixer may be expected.
► The highest mixing performance was approximately in the range of 70° to 90°.