Study of a flat-bottomed cylindrical silo with different orifice shapes

Converging orifice used to control the discharge rate of spherical particles from a flat floor silo

The effect of the converging orifice geometry in a model silo on the discharge rate of monosized spherical particles was studied experimentally and numerically. The cylindrical container was equipped with interchangeable inserts with converging discharge orifices of various upper diameters in the upper base and a constant lower diameter in the lower base. Plastic PLA beads and agricultural granular materials: wheat, rapeseeds, and linseeds were tested. A series of discrete element method simulations corresponding to the performed experiments was conducted with a largely extended set of experimental discharge conditions. In the case of the constant thickness of the insert, the discharge rate initially increased with an increase in the half cone angle of the converging orifice and then the tendency reversed. In the majority of cases, the discharge rate through the converging orifice was higher than through the hopper with the same orifice diameter.

Discrete Element Simulation Study of the Accumulation Characteristics for Rice Seeds with Different Moisture Content

To study the accumulation characteristics of rice seeds with different moisture content, an accurate model of rice seeds was established by 3D scanning technology. The accumulation state of rice seeds by the “point source” accumulation method was analyzed by proportioning and measuring the simulation parameters with different moisture content. The accumulation process was simulated at 10.23%, 14.09%, 17.85%, 21.77%, 26.41% and 29.22% moisture content, respectively. The velocity and force state of the seeds were visually analyzed by using the accumulation process with a moisture content of 29.22%. The accumulation process was divided into four stages according to the velocity characteristics of the seeds. The average force and kinetic energy of the rice seeds outside the cylinder were obtained, and the average force of the rice seeds outside the cylinder was proved to be the direct cause of the velocity change during the accumulation process. The mechanical characteristics of rice seeds in the quasi-static accumulation stage were partitioned and systematically analyzed. The force distribution of the “central depression” structure of rice seeds with a moisture content of 10.23%, 14.09% and 17.85% on the horizontal surface appeared. The higher the moisture content of rice seeds, the more likely the typical “circular” force structure appeared, and the more uniformly the force on the horizontal surface was distributed in the circumference direction.