Evaluation Of Air Velocity Within The Threshing Crescent

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 present article gives the air flow velocity trials within threshing crescent.
Experimental studies were carried out with a stationary tangential threshing
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cylinder stand which consisted of 0.6 m diameter and 1.2 m wide eight rasp bars
tangential threshing cylinder which is surrounded by concave with 146º. Air velocity
was measured at 56 locations, distributed dependent on construction of concave.
The air velocity was measured using a hot wire anemometer unit. The output
data was recorded on PC using 10 bit ADC converter. Nine levels of cylinder peripheral
speed (from 11.0 ms-1 to 23.6 ms-1) at cylinder-concave clearances of: 36
mm at front, 32 mm in middle, and 20 mm at rear part of concave were used in this
experiment. The results of the experiment show that there were significant differences
of air velocity among cylinder peripheral speeds and locations. The air velocity
increased with increased cylinder peripheral speed and towards the rear of the
concave. Air flow velocity within threshing crescent dependence on technological
and constructional parameters of the threshing cylinder is presented.

Article is in lithuanian language