Tver State Technical University, Tver, Russia:

A. L. Yablonev, Head of Department, Doctor of Engineering Sciences, alvovich@mail.ru
D. M. Shcherbakova, Post-Graduate Student

The efficiency of suction of milling chips by pneumatic peat harvesters is largely governed by the height and angle of installation of the suction nozzle relative to the underlying surface. Since there are very few data and recommendations on this topic, in laboratory conditions, using a specially designed and created installation, a series of experimental work was carried out to identify rational values of the height and angle of the nozzle. The criteria were the most pronounced turbulence of the air flow (to create a lifting force) and the maximum length of the axis of the active zone of the suction plume (for a longer time of exposure of the air flow to the milling chips). The results showed that for the two examined types of peat – high-moor peat with a degree of decomposition of 5–10 % and a transitional degree of decomposition of 35–40 % for the maximum allowable fraction of 25 mm, the angle of installation of the suction nozzle of 30–35° is rational, and the height of the nozzle, equal to the size the maximum permissible conditioned fraction of milling chips, is 25 mm. It was with this arrangement of the nozzle th at the length of the axis of the active zone of the suction plume was maximum, and the air flow was with the most pronounced turbulence. To increase the efficiency of the pneumatic harvester, it is proposed to equip the suction nozzles with mouthpieces. The study proves that the maximum efficiency, according to the criterion of the length of the axis of the active zone of the suction flare, has a nozzle installed at an angle of 30–35°, equipped with a mouthpiece with an activation angle of 50–55°. The comparison of the efficiency of the nozzle without a mouthpiece and with a mouthpiece shows that the proposed mouthpiece is able to more than double the length of the axis of the active zone of the suction plume, and, consequently, to increase the efficiency of the machine.

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