## THERMAL SCIENCE

International Scientific Journal

### TWO-PHASE FLOW IN CHANNELS WITH NON-CIRCULAR CROSS-SECTION OF PNEUMATIC TRANSPORT OF POWDER MATERIAL

**ABSTRACT**

The paper presents a numerical simulation of two-phase turbulent flow in straight horizontal channels of pneumatic transport with non-circular cross-section. For the granular flow simulation, we have chosen the flow of solid particles of quartz, flour, and ash in the flow of air, which is transporting fluid. During the modeling of the flow, the transported solid particles are reduced to spherical shapes. A correction of the stress model of turbulence is performed by taking into account the influences of the induction of secondary flows of the second order in the gas phase. The full Reynolds stress model was used for modeling the turbulence, and the complete model is used for the turbulent stresses and turbulent temperature fluxes. All numerical experiments were conducted for the same initial flow conditions and a single uniform grid was adopted for all numerical experiments. The flow is observed in a straight channel of a square cross-section and dimensions of sides of 200 mm and the length of 80 Dh. During the simulation, the fineness of the numerical grid was also tested, and the paper shows results of the numerical grid of the highest resolution beyond which the fineness does not influence the obtained results. The paper offers graphics of velocities of the solid particles transported by the transporting fluid (air) along the channel.

**KEYWORDS**

PAPER SUBMITTED: 2018-04-08

PAPER REVISED: 2018-07-24

PAPER ACCEPTED: 2018-08-08

PUBLISHED ONLINE: 2019-01-19

**THERMAL SCIENCE** YEAR

**2018**, VOLUME

**22**, ISSUE

**Supplement 5**, PAGES [S1407 - S1424]

- Cundall, P. A., Strack, O. D. L., A Discrete Numerical Model for Granular Assemblies, Geotechnique, 29 (1979), 1, pp. 47-65
- Tsuji, Y., et al., Discrete Particle Simulation of Two-Dimensional Fluidized Bed, Powder Technology, 77 (1993), 1, pp. 79-87
- Zhao, X. L., et al., DEM Simulation of the Particle Dynamics in Two-Dimensional Spouted Beds, Powder Technology, 184 (2008), 2, pp. 205-213
- Feng, Y. Q., et al., Discrete Particle Simulation of Gas Fluidization of Particle Mixtures, AIChE Journal, 50 (2004), 8, pp. 1713-1728
- Campbell, C. S., Brennen, C. E., Computer Simulations of Granular Shear Flows, Journal of Fluid Mechanics, 151, (1985), Feb., pp. 167-188
- Hoomans, B. P. B., et al., Discrete Particle Simulation on Bubble and Slug Formation in a Two-Dimensional Gas-Fluidised Bed: a Hard-Sphere Approach, Chemical Engineering Science, 51 (1996), 1, pp. 99-118
- Goldschmidt, M. J. V., et al., Hydrodynamic Modeling of Dense Gas-Fluidised Beds Using the Kinetic Theory of Granular Flow: Effect of Coefficient of Restitution on Bed Dynamics, Chemical Engineering Science, 56 (2001), 2, pp. 571-578
- Li, J., Kuipers, J. A. M., Gas-Particle Interactions in Dense Gas-Fluidized Beds, Chemical Engineering Science, 58 (2003), 3-6, pp. 711-718
- He, Y., et al., Gas-Solid Two-Phase Turbulent Flow in Acirculating Fluidized Bed Riser: an Experimental and Numerical Study, Proceedings, 5th Word Congress on Technology, Orlando, Fla., USA, 2006, pp. 1-9
- Tanaka, T., et al., Cluster Formation and Particle-Induced Instability in Gas-Solid Flows Predicted by the DSMC Method, International Journal of JSME, 39 (1996), 2, pp. 239-245
- Fuzhen, C., et al., Coupled SDPH-FVM Method for Gas-Particle Multiphase Flow: Methodology, Inter-national Journal for Numerical Methods in Engineering, 109 (2017), 1, pp. 73-101
- Jaffari, M., et al., Modelling and Numerical Investigation of Erosion Rate for Turbulent Two-Phase Gas Solid Flow in Horizontal Pipes, Powder Technology, 267 (2014), Nov., pp. 362-370
- Lain, S., Study of Turbulent Two-Phase Gas-Solid Flow in Horizontal Channels, Indian Journal of Chemical Technology, 20 (2013), 2, pp. 128-136
- Schellander, D., et al., Numerical Study of Dilute and Dense Poly-Dispersed Gas-Solid Two-Phase Flows Using an Eulerian-Lagrangian Hybrid Model, Chemical Engineering Science, 95 (2013), May, pp. 107-118
- Milanović, S., et al., The Influence of Secondary Flow in a Two-Phase Gas-Solid System in Straight Channels with a Non-Circular Cross-Section, Thermal Science, 20 (2016), Suppl. 5, pp. S1419-S1434
- Hinze, J. O., Turbulence, McGraw-Hil, New York, USA, 1959
- Bird, B. R, et al., Transport Phenomena, John Wiley and Sons, New York, USA, 2001
- Stevanović, Ž., Numerical Aspects of Turbulent Impulse and Heat Transfer (in Serbian), Faculty of Me-chanical Engineering, University of Nis, Nis, Serbia, 2008
- ***, Mathematical Models of Turbulent Transport Processes, (in Serbian), Collection of Papers Dedicat-ed to the Academician Muhamed Riđanović, Academy of Sciences and Arts of Bosnia and Herzegovina, Sarajevo, B&H, 1984
- Hanjalić, K., General Equations of Transport Processes (in Serbian), Faculty of Mechanical Engineer-ing, University of Sarajevo, Sarajevo, B&H, 1976
- Sijerčić, M., Mathematical Modelling of Complex Turbulent Transport Processes (in Serbian), Yugoslav Society of Thermal Engineers - Edition: Scientific Research Achievements, Belgrade, 1998
- Milanović, S., Research into the Turbulent Two-Phase Flow in Straight Channels with a Non-Circular Cross-Section during the Pneumatic Transport of Granular Materials, Ph. D. thesis, Faculty of Mechani-cal Engineering, University of Nis, Nis, Serbia, 2014
- Bogdanović, B., et al., Flying Pneumatic Transport (in Serbian), Faculty of Mechanical Engineering, University of Nis, Nis, Serbia, 2009
- Po, J. K., Developing Turbulent Flow in the Entrance Region of a Square Duct, M. Sc. thesis, University of Washington, 1975
- Perkins, H. J., The Formation of Streamwise Vorticity in Turbulent Flow, Journal of Fluid Mechanics, 44 (1970), 4, pp. 721-740