Numerical Comparison of Rushton Turbine and CD-6 Impeller in Non-Newtonian Fluid Stirred Tank

A computational fluid dynamics simulation is done for
non-Newtonian fluid in a baffled stirred tank. The CMC solution is
taken as non-Newtonian shear thinning fluid for simulation. The
Reynolds Average Navier Stocks equation with steady state multi
reference frame approach is used to simulate flow in the stirred tank.
The turbulent flow field is modelled using realizable k-ε turbulence
model. The simulated velocity profiles of Rushton turbine is
validated with literature data. Then, the simulated flow field of CD-6
impeller is compared with the Rushton turbine. The flow field
generated by CD-6 impeller is less in magnitude than the Rushton
turbine. The impeller global parameter, power number and flow
number, and entropy generation due to viscous dissipation rate is also
reported.

• Akhilesh Khapre
• Basudeb Munshi

• Computational fluid dynamics
• non-Newtonian
• Rushton turbine
• CD-6 impeller
• power number
• flow number
• viscous dissipation rate.

[1] Y. Kawase, K. Shimizu, T. Araki and T. Shimodaira, “Hydrodynamics in
three-phase stirred tank reactors with non-Newtonian fluids,” Industrial
& Engineering Chemistry Research, vol. 36, no. 1, pp. 270–276, 1997.
[2] H. Ameur, M. Bouzit and M. Helmaoui, “Numerical study of fluid flow
and power consumption in a stirred vessel with a Scaba 6SRGT
impeller,” Chemical and Process Engineering, vol. 32, no. 4, pp. 351–
366, 2011.
[3] E. Koutsakos and A.W. Nienow, Effects of rheological properties of
simulated fermentation broths on flows in stirred bioreactors: A laser
anemometry study, Rheology of food, pharmaceutical and biological
martials with general rheology, R.E. Carter (ed.), pp. 284–303, 1990.
[4] J. Nouri and J. Whitelaw, “Flow characteristics of stirred reactors with
Newtonian and non-Newtonian fluids,” AIChE Journal, vol. 36, no. 4,
pp. 627–629, 1990.
[5] J. Solomon, T. Elson and A. W. Nienow, “Cavern sizes in agitated fluids
with a yield stress,” Chemical Engineering Communication, vol. 11, no.
1-3, pp. 143-164, 1981.
[6] B. Venneker, J. Derksen and H. E. A. Van den Akker, “Turbulent flow
of shear-thinning liquids in stirred tanks-The effects of Reynolds number
and flow index,” Chemical Engineering Research and Design, vol. 88,
no. 7A, pp. 827–843, 2010.
[7] H. Ameur and M. Bouzit, “Mixing in shear thinning fluids,” Brazilian
Journal of Chemical Engineering, vol. 29, no. 2, pp. 349–358, 2012.
[8] M. Dular, T. Bajcar, L. Slemenik-Perse, M. Zumer and B. Sirok,
“Numerical simulation and experimental study of non-Newtonian mixing
flow with a free surface,” Brazilian Journal of Chemical Engineering,
vol. 23, no. 4, pp. 473–486, 2006.
[9] P. Tanguy, M. Heniche, C. Rivera, C. Devals and K. Takenaka, “Recent
developments in CFD applied to viscous and non-Newtonian mixing in
agitated vessels,” Paper presented at 5th International Conference on
CFD in the Process Industries, CSIRO, Melbourne, Australia, 2006.
[10] W. Kelly and B. Gigas, “Using CFD to predict the behaviour of power
law liquids near axial-flow impellers operating in the transitional flow
regime,” Chemical Engineering Science, vol. 58, no. 10, pp. 2141-2152,
2003.
[11] W. Binxin, “CFD investigation of turbulence models for mechanical
agitation of non-Newtonian fluids in anaerobic digesters,” Water
Research, vol. 45, no. 5, pp. 2082-2094, 2011.
[12] S. Masiuk and H. Lacki, “Power consumption and mixing times for
Newtonian and non-Newtonian liquids mixing in a ribbon mixer,” The
Chemical Engineering Journal, vol. 52, no. 1, pp. 13–17, 1993.
[13] J. Netusil and F. Rieger, “Power consumption of screw and helical
ribbon agitators in highly viscous pseudoplastic fluids,” The Chemical
Engineering Journal, vol. 52, no. 1, pp. 9–12, 1993.
[14] M. Ammar, W. Chtourou, Z. Driss, M. S. Abid, “Numerical investigation
of turbulent flow generated in baffled stirred vessels equipped with three different turbines in one and two stage system,” Energy, vol. 36, no. 8,
pp. 5081–5093, 2011.
[15] N. Dohi, T. Takahashi, K. Minekawa, Y. Kawase, “Power consumption
and solid suspension performance of large-scale impellers in gas-liquidsolid
three phase stirred tank reactors,” Chemical Engineering Journal,
vol. 97, no. 2-3, pp. 103–114, 2004.
[16] A. R. Khopkar and P. A. Tanguy, “CFD simulation of gas-liquid flows in
stirred vessel equipped with Rushton turbines: influence of parallel,
merging and diverging flow configuration,” Chemical Engineering
Science, vol. 63, no. 14, pp. 3810–3820, 2008.
[17] G. F. Naterer and O. B. Adeyinka, “Magnetic Stirring Tank and Parallel
Channel Flow,” Entropy, vol. 11, no. 3, pp. 334–350, 2009.
[18] Z. Driss, S. Karray, W. Chtourou, H. Kchaou and M. S. Abid, “A study
of mixing structure in stirred tanks equipped with multiple four-blade
Rushton impellers,” The Archive of Mechanical Engineering, vol. 59,
no. 1, pp. 53–72, 2012.
[19] Ansys Fluent 13, Theory Guide, Ansys Inc., U.S.A., 2011.
[20] A. Bakker, A new gas dispersion impeller with vertically asymmetric
blades, The Online CFM Book, 2000. http://www.bakker.org/cfm
[21] A. B. Metzner and R. E. Otto, “Agitation of non-Newtonian fluids,”
AIChE Journal, vol. 3, no. 1, pp. 3-10, 1957.
[22] T. Cebeci and P. Bradshaw, Physical and computational aspects of
convective heat transfer, New York: Springer, 1984.
[23] F. Kock and H. Herwig, “Entropy production calculation for turbulent
shear flows and their implementation in cfd codes,” International Journal
of Heat and Fluid Flow, vol. 26, no. 4, pp. 672–680, 2005.
[24] S.V. Patankar, Numerical heat transfer and fluid flow, Series in
Computational Methods in Mechanics and Thermal Sciences,
Hemisphere, Washington, DC, 1980.
[25] D. Deglon and C. Meyer, “CFD modeling of stirred tanks: Numerical
considerations,” Minerals Engineering, vol. 19, no. 10, pp. 1059–1068,
2006.
[26] R. L. Bates, P. L. Fondy and R. R. Corpstein, “An examination of some
geometrical parameters of impeller power,” Industrial & Engineering
Chemistry Process Design and Development, vol. 2, no. 4, pp. 310–314,
1963.