Experimental study of air flow variation in a combine harvester threshing apparatus

Abstract

The rotation of combine harvester threshing cylinder creates an air flow within threshing crescent, part of which is directed through the openings in the concave.The information about variation of air flow speed in the threshing crescent and in concave grate-bar would enable modelling the optimal design of filler plates of threshing cylinder. Air velocity was measured at 144 locations, distributed dependent on construction of concave. For the purpose of investigation software AirLab and measuring equipment were produced. The calculated confidence interval for arithmetic means of air flow speed and amplitudes of speed variation show that uniformity of air flow speed in width of the concave increases when spaces between rasp bars are covered with filler plates. The design of cylinder filler plates has no significant effect on air flow speed in the concave grate-bars. However, within threshing crescent, air flow speed in end of the concave length is lower when spaces between rasp bars are covered with filler plates.