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Investigation of Increasing the Heat Transfer from Flat Surfaces Using Boundary Layer Excitation

Authors: M.H.Ghaffari

Abstract:

The present study is concerned with effect of exciting boundary layer on increase in heat transfer from flat surfaces. As any increase in heat transfer between a fluid inside a face and another one outside of it can cause an increase in some equipment's efficiency, so at this present we have tried to increase the wall's heat transfer coefficient by exciting the fluid boundary layer. By a collision between flow and the placed block at the fluid way, the flow pattern and the boundary layer stability will change. The flow way inside the channel is simulated as a 2&3-dimensional channel by Gambit TM software. With studying the achieved results by this simulation for the flow way inside the channel with a block coordinating with Fluent TM software, it's determined that the figure and dimensions of the exciter are too important for exciting the boundary layer so that any increase in block dimensions in vertical side against the flow and any reduction in its dimensions at the flow side can increase the average heat transfer coefficient from flat surface and increase the flow pressure loss. Using 2&3-dimensional analysis on exciting the flow at the flow way inside a channel by cylindrical block at the same time with the external flow, we came to this conclusion that the heat flux transferred from the surface, is increased considerably in terms of the condition without excitation. Also, the k-e turbulence model is used.

Keywords: Cooling, Heat transfer, Turbulence, Excitingboundary layer.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1063074

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References:


[1] Jafari Nasr, M.R. and Polley, G.T., "An algorithm for cost comparison of optimized shell and tube heat exchanger with tube insert and plain tubes", Chem. Eng. Tech., Vol.23, pp.267-272, 2000.
[2] Tijing, L.D., Pak, B.C., "A study on heat transfer enhancement using straight and twisted internal fin inserts", International Communications in Heat and Mass Transfer, xx (2006) xxx-xxx.
[3] Drust,.F., and Becker,S., FY, "Boundary layer transition included by a roughness element", international report, University Erlangen, Germany, INEEL LDRD Program, 1973.
[4] Chiriac, Y.A. and Ortega, A., "A numerical study of the unsteady flow and heat transfer in a transitional confined slot jot impinging on a isothermal surface", Int., j., heat and mass transfer. Vol.45, pp1237- 1248, 2002.
[5] Kahrom M., Haghparast P., Javadi M., "Neural Network Application in Boundary Layer Phenomenon for Cooling the Turbine Blades to Improve the Cooling Process", 16th International Conference on Mechanical Engineering, Iran, 2008.
[6] Beredberg, J., "Turbulence Modeling For Internal Cooling Gas - Turbine Blades", PhD Thesis, Chalmers University of Technology, Sweden, 2002.
[7] Ghobadi, A., Kahrom, M., "Cooling Turbine Blades using Exciting Boundary Layer", International conference on computational and mathematical engineering, Penang, Malaysia, 2010.
[8] B. E. Launder, D. B. Spalding. "Lectures in Mathematical Models of Turbulence", Academic Press., London, England, 1972.
[9] T.B Gatski, M.Y.Hussaini, J.L. Lumley, "Simulation and Modeling of Turbulent flows", Oxford University Press, New York, 1996.
[10] "Fluent User-s Guide", Version 4.3, vols, 1-4, Fluent Incorporated, Lebanon, NH, 1995.
[11] S. V. Patankar, "Numerical Heat Transfer and Fluid Flow", McGraw- Hill, 1980.