CFD–DEM simulation of material motion in air-and-screen cleaning device

In this work, a numerical study of the gas–solid flow in an air-and-screen cleaning shoe is carried out by use of the combined Discrete Element Method (DEM) and Computational Fluid Dynamics (CFD) model where the motion of discrete particles phase is obtained by DEM which applies EDEM software and the flow of continuum fluid by the traditional CFD which solves the Navier–Stokes equations at a computational cell scale. The effect of inlet airflow velocity is studied and analyzed in terms of grains and short straws’ longitudinal velocity and vertical height, and cleaning loss. Simulation results showed that, in a certain range, different inlet airflow velocity only affects the magnitude of airflow velocity in the cleaning shoe, but does not affect the distribution regularity of flow field in the cleaning shoe. With the inlet airflow velocity increase, vibrating screen processing power improves, while grain losses increase. Grains mainly concentrate on 4–12 sections under the screen surface. Comparison of numerical simulation results with experiments has demonstrated adequate agreement. It showed that numerical simulation of material motion on vibrating screen of air-and-screen cleaning device based on CFD–DEM is feasible. The results provide a basis for improving the design on air-and-screen cleaning device of combine harvester.

• CFD–DEM coupling is a good tool for studying the air-and-screen cleaning device of combine harvester.
• Inlet airflow velocity has more influence on the longitudinal velocity of short straws than that of grains.
• Comparison of simulated and experimental results shows a good degree of agreement.