INVESTIGATION OF THE MOVEMENT OF GRAIN MATERIAL PARTICLES IN A VERTICAL CHANNEL UNDER THE ACTION OF AIR FLOW PULSATIONS

Separation of grain mass in the air stream is one of the most common technological operations during post-harvest processing of grain. Most grain separators are equipped with air cleaning systems for grain mass. It is important to further improve the quality of grain separation into fractions by existing types of air separators. The creation of new and improvement of existing pneumatic separation systems is inextricably linked with the further development of the scientific basis of air separation and the creation of more accurate mathematical models that take into account the forces arising from changes in air flow rate, both coordinates and time. The action of forces on the grain due to the non-stationary flow of air and its unevenness under certain conditions can increase, or enhance, the efficiency of separation of the components of the grain material by aerodynamic properties. To study the process of moving grain material under the action of uneven, non-stationary air flow in the pneumatic separation channel, it is necessary to formulate a mathematical description that will determine the trajectories of grain in the air flow with a velocity gradient and pulsations. The article theoretically determines the regularities of grain motion and improves the mathematical model of the dynamics of solid grain motion in the vertical air flow, which differs from those known in that it takes into account the unevenness of the velocity field, the action of lateral forces, material concentration. The use of pulsed air flow allows us to increase the divergence of the trajectories of the grains by 10–15%. The solution of the system of equations with initial conditions is made in the form of trajectories of grain in vertical air flow, which allows us to calculate their trajectories differing in sailing coefficients and to determine rational values of design parameters of pneumatic gravity separators.