Conjugate problem of combined radiation and laminar forced convection separated flow

Document Type : Research Article

Authors

Mechanical Engineering Department, School of Engineering, Shahid Bahonar University of Kerman, Kerman, Iran

Abstract

This paper presents a numerical investigation for laminar forced convection flow of a radiating gas in a rectangular duct with a solid element that makes a backward facing step. The fluid is treated as a gray, absorbing, emitting and scattering medium. The governing differential equations consisting the continuity, momentum and energy are solved numerically by the computational fluid dynamics techniques. Since the present problem is a conjugate one and both gas and solid elements are considered in the computational domain, simultaneously, the numerical solution of Laplace equation is obtained in the solid element for temperature calculation in this area. Discretized forms of these equations are obtained using the finite volume method and solved by the SIMPLE algorithm. The radiative transfer equation (RTE) is also solved numerically by the discrete ordinate method (DOM) for computation of the radiative term in the gas energy equation.The streamline and isotherm plots in the gas flow and the distributions of convective, radiative and total Nusselt numbers along the solid-gas interface are presented. Besides, the effects of radiation conduction parameter and also solid to gas conduction ratio as two important parameters on thermo hydrodynamic characteristics of such thermal system are explored. It is revealed that the radiative Nusselt number on the interface surface is much affected by RC parameter but the radiation conduction parameter has not considerable effect on the convective Nusselt number. Comparison between the present numerical results with those obtained by other investigators for the case of non-conjugate problems shows good consistency.

Keywords

References

[1]Vradis, George C., and Lara Vannostrand. “Laminar coupled flow downstream of an asymmetric sudden expansion.” Journal of thermophysics and heat transfer 6.2 (1992): 288-295.
[2]Kondoh, T., Y. Nagano, and T. Tsuji. “Computational study of laminar heat transfer downstream of a backward-facing step.” International Journal of Heat and Mass Transfer 36.3 (1993): 577-591.
[3]Erturk, Ercan. “Numerical solutions of 2-D steady incompressible flow over a backward-facing step, Part I: High Reynolds number solutions.” Computers & Fluids 37.6 (2008): 633-655.
[4]Abu-Nada, Eiyad. “Numerical prediction of entropy generation in separated flows.” Entropy 7.4 (2005): 234-252.
[5]Abu-Nada, Eiyad. “Entropy generation due to heat and fluid flow in backward facing step flow with various expansion ratios.” International Journal of Exergy 3.4 (2006): 419-435.
[6]B. F. Armaly, A. Li and J. H. Nie, Measurements in threedimensional laminar separated flow, International Journal of Heat and Mass Transfer, 46 (2003) 3573-3582.
[7]Armaly, Bassem F., An Li, and J. H. Nie. “Measurements in three-dimensional laminar separated flow.” International Journal of Heat and Mass Transfer 46.19 (2003): 3573- 3582.
[8]Ansari, A. B., and SA Gandjalikhan Nassab. “Thermal characteristics of convective flows encountered in a 2-D backward facing step under the effect of radiative heat transfer.” International Review of Mechanical Engineering 4.6 (2010): 711-718.
[9]Vynnycky, M., et al. “Forced convection heat transfer from a flat plate: the conjugate problem.” International Journal of Heat and Mass Transfer 41.1 (1998): 45-59.
[10]Chiu, Han-Chieh, Jer-Huan Jang, and Wei-Mon Yan. “Mixed convection heat transfer in horizontal rectangular ducts with radiation effects.” International Journal of Heat and Mass Transfer 50.15 (2007): 2874-2882.
[11]Chiu, Han-Chieh, and Wei-Mon Yan. “Mixed convection heat transfer in inclined rectangular ducts with radiation effects.” International Journal of Heat and Mass Transfer 51.5 (2008): 1085-1094.
[12]Rao, C. Gururaja, C. Balaji, and S. P. Venkateshan. “Effect of surface radiation on conjugate mixed convection in a vertical channel with a discrete heat source in each wall.” International journal of heat and mass transfer 45.16 (2002): 3331-3347.
[13]Juncu, Gh. “Conjugate heat/mass transfer from a circular cylinder with an internal heat/mass source in laminar cross flow at low Reynolds numbers.” International journal of heat and mass transfer 48.2 (2005): 419-424.
[14]Juncu, G. (2008). Unsteady heat transfer from an elliptic cylinder. International Journal of Heat and Mass Transfer, 51(3), 920-928.
[15]Mathews, Roy N., C. Balaji, and T. Sundararajan. “Computation of conjugate heat transfer in the turbulent mixed convection regime in a vertical channel with multiple heat sources.” Heat and mass transfer 43.10 (2007): 1063-1074.
[16]Kanna, P. Rajesh, and Manab Kumar Das. “Conjugate heat transfer study of backward-facing step flow–a benchmark problem.” International journal of heat and mass transfer 49.21 (2006): 3929-3941.
[17]Modest, Michael F. Radiative heat transfer. Academic press, 2013.
[18]Keshtkar, M. M., and SA Gandjalikhan Nassab. “Theoretical analysis of porous radiant burners under 2-D radiation field using discrete ordinates method.” Journal of Quantitative Spectroscopy and Radiative Transfer 110.17 (2009): 1894-1907.
[19]Bejan, Adrian. Convection heat transfer. John wiley & sons, 2013.
[20]Ansari, A. B., and SA Gandjalikhan Nassab. “Study of laminar forced convection of radiating gas over an inclined backward facing step under bleeding condition using the blocked-off method.” ASME Journal of heat transfer 133.7 (2011): 072702.
[21]Patankar, Suhas V., and D. Brian Spalding. “A calculation procedure for heat, mass and momentum transfer in three-dimensional parabolic flows.” International Journal of Heat and Mass Transfer 15.10 (1972): 1787-1806.
[22]Abu-Nada, Eiyad. “Investigation of entropy generation over a backward facing step under bleeding conditions.” Energy Conversion and Management 49.11 (2008): 3237-3242.
[23]Atashafrooz, Meysam, and Seyyed Abdolreza Gandjalikhan Nassab. “Numerical analysis of laminar forced convection recess flow with two inclined steps considering gas radiation effect.” Computers & Fluids 66 (2012): 167-176.
AUT Journal of Modeling and Simulation
Volume 49, Issue 1
June 2017
Pages 123-130

Files

Share

How to cite

Statistics