Emre KAHRAMANOĞLU, Savaş SEZEN, Seyfettin BAYRAKTAR

İç akışlardaki hidrodinamik giriş uzunluğu üzerine hesaplamalı akışkanlar dinamiği analizleri

Bu sayısal çalışmada, en kesit şekillerinin ve yüzey pürüzlülüklerinin borulardaki hidrodinamik giriş uzunluğuna olan etkileri farklı Reynolds (Re) sayıları için incelenmiştir. Dairesel, kare ve eşkenar üçgen kesitli borulardaki türbülanslı akışı analiz etmek için standart k-e türbülans modeli kullanılmıştır. Analizler pürüzlü yüzeyli borulardaki giriş uzunluğunun pürüzsüz borulardakine göre daha kısa olduğunu göstermiştir. Ayrıca, yüzey pürüzlülüğünü artırmak borunun en kesit şeklinden bağımsız olarak giriş uzunluğunu kısaltmaktadır. Eşkenar üçgen kesitli boruların en uzun, dairesel kesitli boruların ise en kısa giriş uzunluğuna sahip oldukları görülmüştür. Re sayısı giriş uzunluğu üzerinde önemli etkilere sahiptir ve Re sayısı ne kadar büyürse giriş uzunluğunun da o kadar arttığı sonucuna varılmıştır.

Anahtar Kelimeler:

Hesaplamalı akışkanlar dinamiği, İç akışlar, Pürüzlülük, Türbülanslı akışlar, Giriş uzunluğu

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Cengel YA, Cimbala JM. Fluid Mechanics: Fundamentals and Application. 1st ed. McGraw-Hill, 2006.
Yuksel Y. Advanced Fluid Mechanics. Istanbul, Beta, 2014.
Sahu M, Singh P, Mahapatra SS, Khatua KK. “Prediction of entrance length for low reynolds number flow in pipe using neuro-fuzzy inference system”. Expert Systems with Applications, 39(4), 4545-4557, 2012.
White FM. Fluid Mechanics. 8th ed. New York, USA, McGrew Hill, 2015.
Munson BR, Okiishi TH, Huebsch WW, Rothmayer AP. Fundamentals of Fluid Mechanics. 7th ed. John Wiley & Sons, 2013.
Nakayama Y, Boucher RF. Introduction to Fluid Mechanics. Butterworth-Heinemann, 1998.
Massey B, Ward-Smith J. Mechanics of Fluids. 8th ed. Taylor and Francis, 2006.
Friedmann M, Gills J, Liron N. “Laminar flow in pipe at low and moderate reynolds numbers”. Applied Scientific Research, 19(1), 426-438, 1968.
Chen RY. “Flow in the entrance region at low Reynolds numbers”. Journal of Fluid Engineering, 95(1), 153-158, 1973.
Durst F, Ray S, Unsal B, Bayoumi OA. “The development lengths of laminar pipe and channel flows”. Journal of Fluids Engineering, 127(6), 1154-1160, 2005.
Bahrami M, Tamayol A. “Laminar flow in microchannels with noncircular cross section”. Journal of Fluids Engineering, 132(11), 111201-111201, 2010.
Anselmet F, Ternat F, Amielh M, Boiron O, Boyer P, Pietri L. “Axial development of the mean flow in the entrance region of turbulent pipe and duct flows”. Comptes Rendus Mécanique, 337(8), 573-584, 2009.
Di Nucci C, Spena AR. “Mean velocity profiles of two-dimensional fully developed turbulent flows”. Comptes Rendus Mécanique, 340(9), 629-640, 2012.
Bhandari D, Singh S. “Analysis of fully developed turbulent flow in a pipe using computational fluid Dynamics”. International Journal of Engineering Research and Technology, 1(5), 1-8, 2012.
Duan Z, Yovanovich MM, Muzychka YS. “Pressure drop for fully developed turbulent flow in circular and noncircular ducts”. Journal of Fluids Engineering, 134(66), 061201- 061210, 2012.
Tongpun PT, Bumrungthaichaichan E, Wattananusorn S. “Investigation of entrance length in circular and noncircular conduits by computational fluid dynamics simulation”. Songklanakarin Journal of Science and Technology, 36(4), 471-475, 2014.
Shah RK, London AL. “Flow Friction in Straight and Curved Ducts-A Summary of Analytical Solutions”. Technical Department of Mechanical Engineering, Stanford University, Stanford, California, USA, Report, 75, 1971.
Lee PS, Garimella SV. “Thermally Developing Flow and Heat Transfer on Rectangular Microchannels of Different Aspect Ratios”. CTRC Research Publications. Paper 23, 2006.
Hayes RE, Donoso-Bravo A, Mmbaga JP. “Entry length effects for momentum, heat and mass transfer in circular ducts with laminar flow”. Canadian Journal of Chemical Engineering, 93, 863-869, 2015.
Kandlikar SG, Joshi S, Tian S. “Effect of surface roughness on heat transfer and fluid flow characteristics at low reynolds numbers in small diameter tubes”. Heat Transfer Engineering, 24(3), 4-16, 2003.
Hasan O. “Heat transfer analysis in thermal entrance region under turbulent flow conditions”. Asia-Pacific Journal of Chemical Engineering, 8(4), 579-592, 2013.
Hayes RE, Donoso-Bravo A, Mmbaga JP. “Entry length effects for momentum, heat and mass transfer in circular ducts with laminar flow”. The Canadian Journal of Chemical Engineering, 93(5), 863-869, 2015.
Wang LB, Wang QW, He YL, Tao WQ. “Experimental and numerical study of developing turbulent flow and heat transfer in convergent/divergent square duct”. Heat and Mass Transfer, 38(4), 399-408, 2002.
Alberts-Chico X, Perez-Segarra CD, Oliva A, Bredberg J. “Analysis of wall-function approaches using two-equation turbulence models”. International Journal of Heat and Mass Transfer, 51(19-20), 4940-4957, 2008.
Versteeg HK, Malalasekera W. An Introduction to Computational Fluid Dynamics: The Finite Volume Method. 2nd ed. Pearson Prentice Hall, 2007.
Lin CX, Ebadian MA. “The effects of ınlet turbulence on the development of fluid flow and heat transfer in a helically coiled pipe”. International Journal of Heat and Mass Transfer, 42(4), 739-751, 1999.