Calculation of particle trajectories in the pneumatic separation channel using various methods

Abstract

The article presents the comparison testing of particle trajectories in the pneumatic separation channel (PSC) of the pneumatic seed separator SP-2F and its bend, calculated using computer simulation method and two experimental-theoretical methods. They are based on taking into account the real airflow velocity field. In the first variant, the velocity field was measured in an idle mode, in the second at the nominal grain load. The studies were carried out in a vertical PSC with a supporting grid divided into two parts by a partition wall. In the variant with the theoretical velocity field the trajectories of light and grain impurities in the first part of the PSC are shifted closer to the outer wall. In the second part of the channel, particles with hovering speed of 8.0...10.0 m/s are carried upwards, and with hovering speed of 11.0 m/s they fall down into the purified material. In the variant of the experiment in an idle mode, particles with the hovering speed of 7.0...10.0 m/s rise up in the second part of the PSC. In the variant with grain load, particles with the hovering speed of 7.0...9.0 m/s rise upward and ricochet off the inner walls of the PSC and a bend wall, and particles with the hovering speed of more than 10.0 m/s fall down into the purified material. In the variant of the experiment with the grain load, the particle velocity with the hovering speed of 5.0...9.0 m/s at the exit of the PSC bend is more evened as compared to other options - 2.3...2.7 m/s, and the velocity vector of most particles is directed at a lower angle to the horizontal: from 4 up from the horizontal to 17 down from the horizontal. The most accurate is the calculation of particle trajectories using the velocity field in the PSC at the nominal grain load. The results of the study can be useful in the theoretical substantiation of the design parameters of pneumatic systems of grain cleaning machines.