Effect of paddy grain flow behaviour on orientation adjustment mechanisms in rubber roll huller feeding chute

In the hulling process of rubber roll hullers, disordered paddy grain orientation reduces hulling efficiency. This results in material wastage, diminished product quality. While conventional long feeding chutes exhibit inherent orientation adjustment capabilities, their fundamental mechanisms remain poorly understood. This study employed the discrete element method (DEM) to simulate paddy grain motion dynamics within the feeding chute, elucidating the orientation adjustment mechanism through granular flow analysis. The findings demonstrate that elevated feeding rates improve the vertical alignment of paddy grains, albeit at the cost of increased breakage percentage. Spatial analysis reveals that grain alignment is suppressed by shear rate while being enhanced by hydrostatic pressure across the chute width. Furthermore, wall effects modify these parameters, resulting in strengthened vertical alignment near the sidewalls while marginally reducing it in central regions. Based on these findings, an innovative baffled feeding chute was developed that effectively regulates shear rate and inter-particle hydrostatic pressure through controlled wall effects. Experimental validation confirmed a 1.8 % enhancement in hulling effectiveness without compromising breakage rates compared to conventional designs. This research provides both theoretical foundations and practical solutions for optimising rubber roll huller feeding systems.