Thermo-Hydraulic Performance Evaluation of Inclined Vortex Generators

Abstract:

In the present study, a commercial finite volume package ANSYS FLUENT 14.5 has been used to determine thermo-hydraulic performance of two different vortex generator (VG) configurations, namely, flow-up and flow-down, located in triangular ducts. A comprehensive literature survey on flow-up and flow-down configurations has shown that there are completely opposite results obtained in terms of performance of the two configurations. In some studies, flow-up configuration showed better performance characteristics over flow-down configuration while in other studies flow-down configuration was found better. This has been motivated the present authors to make a study covering the two VG configurations to find out which one has a better performance over the other one. Therefore flow and thermal fields together with the secondary flow induced by the two VG configurations have been analyzed extensively. The geometry comprised of double row of VGs located on the slant surfaces of equilateral triangular ducts. The angle of inclination of the VGs made with the flow direction is 30°. The results show that flow-down configuration has a 40.65% higher thermo-hydraulic performance over the flow-up configuration for Re=5000. It is also shown that the heat is transferred at a further downstream distance allowing in a reduction in the number of VGs to be used in of flow down case.

• Periodical: Advanced Materials Research (Volume 853)
• Pages: 317-322
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.853.317
• Online since: December 2013
• Authors: Azize Akcayoglu*, Halil Cebeci, Celal Nazli
• Keywords: CFD, Equilateral Triangular Duct, Thermo-Hydraulic Performance, Vortex Generator

References

[1] C.W. Leung, S.D. Probert: Forced-convective turbulent flows through horizontal ducts with isosceles-triangular internal cross-sections. Appl. Energy Vol. 57 (1997), pp.13-24.

DOI: 10.1016/s0306-2619(96)00021-9

[2] R.K. Shah, A.L. London: Laminar Flow Forced Convection in Ducts (AcademicPress, New York 1978).

[3] Y.H. Zhang, X. Wu, L.B. Wang, K.W. Song, Y.X. Dong, S. Liu: Comparison of heat transfer performance of tube bank fin with mounted vortex generators to tube bank fin with punched vortex generators. Exp. Therm. Fluid Sci. Vol. 33 (2008), pp.58-66.

DOI: 10.1016/j.expthermflusci.2008.07.002

[4] R. Vasudevan, V. Eswaran, G. Biswas: Winglet-type vortex generators for platefin heat exchangers using triangular fins. Num. Heat Transfer-A Vol. 58 (2000) p.533– 555.

DOI: 10.1080/104077800750020423

[5] A. Akcayoglu: Flow past confined delte-wing type vortex generators. Experimental Thermal and Fluid Science Vol. 35 (2011) pp.112-120.

DOI: 10.1016/j.expthermflusci.2010.08.012

[6] K. Torii, K.M. Kwak, K. Nishino: Heat transfer enhancement accompanying pressure-loss reduction with winglet-type vortex generators for fin-tube heat exchangers. Int. J. Heat Mass Transfer Vol. 45 (2002), p.3795–3801.

DOI: 10.1016/s0017-9310(02)00080-7

[7] C.B. Allison, B.B. Dally: Effect of a delta-winglet vortex pair on the performance of a tube-fin heat exchanger. Int. J. Heat Mass Transfer Vol. 50 (2007), 5065–5072.

DOI: 10.1016/j.ijheatmasstransfer.2007.08.003

[8] M.H. Biswas, G. Torii, K., Fujii, D. Nishino: Numerical and experimental determination of flow structure and heat transfer effects of longitudinal vortices in a channel flow. Int. J. Heat Mass Transfer Vol. 39 (1996), p.3441–3451.

DOI: 10.1016/0017-9310(95)00398-3

[9] E. Kim, J.S. Yang: An experimental study of heat transfer characteristics of a pair of longitudinal vortices using color capturing technique. Int. J. Heat Mass Transfer Vol. 45 (2002), p.3349–3356.

DOI: 10.1016/s0017-9310(02)00054-6

[10] M. Fiebig, A. Valencia, N.K. Mitra: Wing-type vortex generators for fin-andtube heat exchangers. Exp. Therm. Fluid Sci. Vol. 7 (1993), p.287–295.

DOI: 10.1016/0894-1777(93)90052-k

[11] R. L. Webb, E. R. G. Eckert, R. J. Goldstein: HeatTransfer and Friction in Tubes with Repeated Rib Roughness. International Journal of Heat and Mass Transfer, Vol. 14 (1971), p.601–617.

DOI: 10.1016/0017-9310(71)90009-3

[12] R. Vasudevan, V. Eswaran, G. Biswas: Winglet-type vortex generators for plate fin heat exchangers using triangular fins. Num. Heat Transfer A. Vol. 58 (2000), p.533– 555.

DOI: 10.1080/104077800750020423

[13] C.N. Lin, Y.W. Liu, J.S. Leu: Heat transfer and fluid flow analysis for plate-fin and oval tube heat exchangers with vortex generators. Heat Transfer Eng. Vol. 29 (2008), p.588–596.

DOI: 10.1080/01457630801922279

[14] T.H. Shih, W. W. Liou, A. Shabbir, Z. Yang, and J. Zhu: A New Eddy Viscosity Model for High Reynolds Number Turbulent Flows - Model Development and Validation. Computers and Fluids Vol. 24 (1995), p.227–238.

DOI: 10.1016/0045-7930(94)00032-t

[15] G. Zhou, Q. Ye: Experimental investigations of thermal and flow characteristics of curved trapezoidal winglet type vortex generators. Applied Thermal Engineering, Vol. 37 (2012), pp.241-248.

DOI: 10.1016/j.applthermaleng.2011.11.024