CFD-DEM coupled study on the characteristics of entrained air and particles dispersion during the particles flow impacting on a heap surface process

Abstract

The process of loading and unloading bulk materials is common in industrial production. This process has become a major source of dust fugitive in industrial plants. In order to understand its dust production mechanism, this paper establishes a physical model of particles flow impacting on the material heap. The CFD-DEM coupling method is validated using experimental data. The effects of heap angle, particle velocity, and hopper outlet diameter on the characteristics of entrained airflow and particle motion are analyzed. The index of ‘entrained flux’ is proposed to assess the influence range of entrained air at the material heap tail. The results indicate that the entrained air velocity exhibits a Gaussian distribution along the normal direction of the material heap surface, with significant fluctuations at the upper part of the material heap and the formation of vortex motion at the material heap tail. The magnitude of the entrained flux is primarily influenced by the location of the vortex, which gradually moves away from the material heap as particle velocity and hopper outlet diameter increase. Conversely, as the heap angle increases, the vortex movement tends to approach the material heap. An objective weighting method is used to analyze the influence weights of the entrained flux, revealing that particle velocity has the highest weight of 39 %, while the hopper outlet diameter has the lowest weight of 26 %.