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Study of spatial viscous liquid flow around a cylinder

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Category: Solid-state physics, mineral processing

Last Updated on 14 July 2013

Published on 14 November 2012

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Authors:

V.I. Krivoshchekov, Cand. Sci. (Tech.), Associate Professor, State Higher Educational Institution “National Mining University”, Senior Lecturer of the Department of Enrichment of Minerals, Dnepropetrovsk, Ukraine

Abstract:

Purpose. Semi-counter flow hydroseparator was developed with layerwise recleaning by means of dividing cylindrical elements with a crack.

Methodology. The minimum value of the coefficient of head-resistance was accepted as a criterion of rational arrangement of tandem cylinders. Dependences of averaged coefficients of head-resistance and carrying capacity were established. On the basis of equations of motion of the two-phase environment the numerical simulation of flowing of tandem cylinders by the spatial stream of viscid liquid was fulfilled.

Findings. The reason for tearing-off the laminar frontier layer from the surface of cylinder is the increase of pressure in diffuser part of stream. Vortexes that unstuck from the cylinder surface are unsteady structures reacting on the least changes of terms of flowing. Formation of these vortexes is accompanied by discrete displacement of points of tearing-off and oscillation of hydrodynamic forces. Therefore even at the fixed values of Reynolds numbers, position of tearing-off points change constantly. In terms of hydroseparator the influence of hydrodynamic terms of flowing of tandem cylinders on character of tearing-off of stream in the first approach it is possible to estimate using the results of research of their flowing around the spatial stream of viscid liquid.
The analysis of the received results for realization of layerwise recleaning of grainy materials, providing the rise of efficiency of division and productivity of semicounterflow hydroseparator with minimum hydraulic resistance was given. The conducted experimental research confirms suitability of the proposed calculation methodology for the substantiation of stream structure of two-phase environment in semicounterflow hydroseparator with layerwise recleaning and perspective of its application for classification and enriching of grainy materials.

Originality. Compared to the spatial flowing of tandem cylinders, flowing of dividing elements in frame of semicounterflow hydroseparator is characterized by lowering of pressure in an external flow after the point of a minimum pressure and forming of zone of capture of viscid liquid by the slot of the dividing element.

Practical value. One of the directions of improvement of quality of concentration products of mineral raw material is to rise the efficiency of hydraulic separation process by development of new methods and vehicles with the rational zone of division and low energy consumption, due to the fact that used for this purpose cylinder-conic hydrocyclones have low (37...56% according to Hancock) technological efficiency conditioned by a number of reasons. On the basis of analysis of these reasons its research and elimination a semicounterflow hydroseparator was developed with layerwise recleaning by means of dividing cylindrical elements with a crack.

References:

1. Кривощеков В.И. Тонкослойная гидросепарация минеральных зерен / Кривощеков В.И. // Збагачення корисних копалин: Наук.-техн. зб. – 2000. – Вип. 8(49). – С. 86–90.

Krivoshchekov, V.I. (2000), “Thin-layer hydro-separation of mineral grains”, Zbahachennia korysnykh kopalyn, issue. 8 (49), pp. 86–90.

2. Кривощеков В.И. Новое формирование потока пульпы в гидросепараторе / Кривощеков В.И. // Збагачення корисних копалин: Наук.-техн. зб. – 2000. – Вип. 9(50). – С. 33–36.

Krivoshchekov, V.I. (2000), “New formation of crushed ore flow in hydroseparator”, Zbahachennia korysnykh kopalyn, issue. 9(50), pp. 33–36.

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Prikhodko, A.A. (2003), Kompyuternye tekhnologii v aerogidrodinamike i teplomassoobmene [Computer Technologies in Aerohydrodynamics and Heat and Mass Exchange], Naukova dumka, Kyiv, Ukraine.

4. Niceno, B. Available at: http://www-inma.univ.tri este.it/~nirftc/research/easymesh/easymesh. html.

5. Русакова Т.И. Численное исследование особенностей отрывного обтекания колеблющегося цилиндра / Т.И. Русакова, В.И. Карплюк // Вісник Дніпропетровського університету. – 2002. – Вип. 6. – Т. 2. – С. 115–123.

Rusakova, Т.I. and Karpliuk, V.I. (2002), “Numerical research of features of a flow with a separation of the varying cylinder”, Visnyk Dnipropetrovskoho universytetu, vol. 2, issue. 6, pp. 115–123.

6. Sharman, B., Lien, F.S., Davidson, L. and Norberg, С. (2005), “Numerical predictions of low Reynolds number flows over two tandem circular cylinders”, International journal for numerical methods in fluids. Mechanics of liquids, 47, pp. 423–447.

7. Кривощеков В.И. Кинетический подход к выводу уравнений движения двухфазной среды в сепарационных аппаратах / Кривощеков В.И. // Обогащение руд. – 2001. – №6. – С.23-26.

Krivoshchekov, V.I (2001), “Kinetic approach to a conclusion of the equations of movement of biphase medium in separation devices”, Zbahachennia rud, no.6, pp. 23–26.

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