DEM simulations and experiments investigating of grain tank discharge of a rice combine harvester

Abstract

Problems associated with the discharge of rice from the grain tank of a combine harvester can be avoided if the tank is designed based on the rice’s flow properties. The precise prediction of the rice movement during discharge from the grain tank is important for the design, manufacture, and improvement of the grain tank. In this research, a discrete element method (DEM) was used to simulate the rice movement during unloading of the grain tank, and the flow type, the pressure exerted on the walls, the particle velocity, the discharge time, and the mass flow rate were analyzed and compared to the experimental results. The results of this research reveal a similarity between the numerical simulation and the experimental test bench. The results show that 1 s after the grain tank starts to unload, a funnel flow was created at the back of the tank and spreads to the rest of the tank. The grain tank is asymmetrical; thus, the pressure exerted on the different walls is not the same. When the tank is filled with rice grain, the four vertical walls receive a little stress compared to the two inclined walls at the bottom of the tank. The walls at the bottom of the tank receive the highest pressure. the two velocity sensors attached to the screw feeder in different parts of the tank to measure the axial speed of the rice grains show that the velocity of the rice velocity is the same between the threads of the screw at the tank exit and inside the tank. the average value of the mass flow rate was 3.5 kg/s for the simulation and 3.35 kg/s for the experiment. The mass flow rate remains constant at zero acceleration of the screw.