The application of the finite-volume method for solving the equations of hydrodynamics to substantiate certain parameters of the pneumatic system of grain cleaning machines

The aim of the research is to substantiate the basic parameters of a two-bubble pneumatic system of a grain-cleaning machine with a single air flow, by applying a finite-volume method for solving the equations of hydrodynamics. The investigated model of the pneumatic system with sedimentary chambers having dimensions similar to the pneumatic system of machines of the OZF series has one airflow inlet, passage sedimentary chambers and a horizontal channel of pre-suction aspiration, one common outlet of the exhausted airflow. The closed hollow design model of the pneumatic system was imported into the calculation area of the software complex. The model of a turbulent incompressible fluid is chosen as a mathematical model, which involves solving the Navier-Stokes equations (momentum conservation law), the continuity equation (the law of conservation of air mass), and the equation of state. To solve the equations of a mathematical model, a rectangular adaptive locally milled grid (ALMG) and a finite volume method were used in which the equations were integrated over the volume of each cell of the computational grid and along the time interval τ. The time step τ was chosen from the stability conditions of the computational algorithm. In accordance with the simulation results and the distribution of airflow rates obtained in the pneumatic system, the overall dimensions of the sedimentary chambers and the length of the baffles were reduced. The length and depth of the sedimentary chamber of pre-aseptic aspiration were 1.1 m and 0.65 m, respectively. The length of the baffle plate of the sedimentary chamber of the pre-suction aspiration is reduced by 4.0 times, the depth of the sedimentary chamber of the canal after aspiration is up to 0.78 m, the sedimentation chamber of the canal is 0.43 m, while the length of the baffle plate is reduced to 0.28 m. The installation of the bottom wall of the chamber on both sides was 40⁰ in relation to horizontal. The resistance of a pneumatic system of reduced dimensions with an idle mode of operation does not exceed 160 Pa. The resistance of the pneumatic system of post-grid aspiration with a vertical pneumatic separating channel of relatively large length and three smooth turns of the air flow is more than 90-95 Pa.