Theory of grain mixture particle motion during aspiration separation

V. Bulgakov¹, S. Nikolaenko¹, I. Holovach¹, V. Adamchuk², S. Kiurchev³, S. Ivanovs⁴ and J. Olt⁵*

¹National University of Life and Environmental Sciences of Ukraine, 15 Heroyiv Oborony Str., UA 03041 Kyiv, Ukraine
²National Scientific Centre, Institute for Agricultural Engineering and Electrification, 11, Vokzalna Str., Glevakcha – 1, Vasylkiv District, UA08631 Kiev Region, Ukraine
³Dmytro Motornyi Tavria State Agrotechnological University, Ukraine
⁴Latvia University of Life Sciences and Technologies, 2 Liela Str., LV-3001 Jelgava, Latvia
⁵Estonian University of Life Sciences, 56 Kreutzwaldi Str., EE51006 Tartu, Estonia
*Correspondence: jyri.olt@emu.ee

Abstract:

The practice of separating grain mixtures with the use of the difference in the aerodynamic properties of their components has proved that the process of separating mixtures in the aspiration separator is the most promising one with regard to the improvement of quality and intensification of production. The authors have developed a new improved design of aspiration seed separators, in which the work process of separating seed material is performed with the use of vibration processes. In this seed material separator, the constant force air flow that acts on the sail members on the central pipe of the separator, when seeds are fed for processing, generates self-excited oscillations in the pipe, which produces centrifugal forces of inertia in the seed feeding system. As a result of the mentioned effect, the propelling force in the process under study substantially increases, accelerating the seeds of different fractions, which differ in their masses, to different velocities. The motion paths of the seed particles change accordingly, heavier particles moving closer to the vertical axis of the aspiration channel, which provides for increasing the efficiency of separation of the seeds of different fractions from each other. In this paper, a new mathematical model is developed for the motion of a seed mixture material particle in the operating space of the separator’s aspiration channel. The mathematical modelling of the process of vibration and aspiration separation has indicated that the separation of the motion paths of the medium and heavy fractions takes place within the range of 20–40 mm; the flying speed of the particles is equal to 3.2–8.0 m s–1, respectively; and their acceleration is equal to 1.8–3.3 m s–2, which provides the necessary conditions for the accurate and high quality separation into the required fractions. In view of the found differences between the kinematic characteristics of the separated fractions of the grain mixture, the diameter of the pipeline for the medium fraction is to be within the range of 90–100 mm, for the heavy fraction – 50–70 mm.

Key words:

air flow, aspiration separator, material particle, mathematical model, seed

Theory of motion of grain mixture particle in the process of aspiration separation

V. Bulgakov¹, S. Nikolaenko¹, I. Holovach¹, A. Boris², S. Kiurchev³, Ye. Ihnatiev³ and J. Olt⁴*

¹National University of Life and Environmental Sciences of Ukraine, 15 Heroyiv Oborony Str., UA 03041 Kyiv, Ukraine
²National Scientific Centre, Institute for Agricultural Engineering and Electrification, 11, Vokzalna Str., Glevakcha 1, Vasylkiv District, UA08631, Kiev Region, Ukraine
³Dmytro Motornyi Tavria State Agrotechnological University, 18B, Khmelnytsky Ave, UA 72310, Melitopol, Zaporozhye Region, Ukraine,
⁴Estonian University of Life Sciences, Institute of Technology, 56 Kreutzwaldi Str., EE51006 Tartu, Estonia
*Correspondence: jyri.olt@emu.ee

Abstract:

The paper describes the development of a mathematical model for the motion of a seed mixture particle in the aspiration channel of the separator after the particle passes the cone-shaped spreader and enters the workspace of the aspiration channel in the pneumatic dynamics and vibration unit devised by the authors. The unique feature of the proposed new design is the presence of the central pipe with sail members in the aspiration channel. The sail members in the air stream generate the self-oscillatory mode of motion of the central pipe, which results in the efficient separation of the grain seed mixture into the required fractions. On the basis of the prepared equivalent schematic model, the differential equations of the motion of a seed mixture particle in the process of aspiration separation have been generated. Basing on the results of the PC-assisted numerical modelling of the motion paths, on which the material particles (seeds) of the heavy and medium fractions travel, it has been established that they move on different courses, and the course of the heavy fraction seeds is such that, after they pass the cone-shaped spreader and advance further in the air stream through the space of the aspiration channel, they move closer to the pipe of the aspiration channel. Also, their velocities and accelerations are greater than the same kinematic parameters of the medium fraction seeds. The seeds of the light fraction move upwards under the action of the air stream and leave the aspiration separator at its top.

Key words: