Abstract：In order to research the phenomeno of uneven conveying, two calculation models with different feeding mode of vertical screw conveyor were built, those were gravity type and horizontal type. The discrete element method and the software of EDEM were used. The simulation parameters, such as inlet velocity, time step and granule attribute parameters, were identified, thus the feasibility of model and parameters were ensured. The two models were simulated respectively. Standard deviation of number of granules was selected as the evaluation index. The results show that compared with the gravity type, granules of sampling region in the feeding rim of the horizontal feeding mode have higher evenness and lower transporting uniformity. This two feeding modes are significantly affected by screw rotation. Some advice is given for the improvement of the two feeding types. The study results have a certain preference for the structure design of feeding rim in the screw conveyor.

Keywords: vertical screw conveyor; feeding mode; discrete element method; force chain; granules unevenness