İZOTROPİK SAÇILMA ORTAMLI KARE GEOMETRİ İÇİNDE TÜRBÜLANSLI DOĞAL TAŞINIM VE IŞINIM ISI TRANSFERİ

Year 2020, Volume: 40 Issue: 2, 207 - 220, 31.10.2020

Mesut Tekkalmaz

https://doi.org/10.47480/isibted.816980

Cited By: 1

Abstract

Farklı ısıtılmış kapalı kare bir geometri içindeki türbülanslı doğal taşınım ve ısıl ışınımın etkisi sayısal olarak incelenmiştir. Kapalı kutu sağ duvardan ısıtılır ve sol duvardan soğutulur. Diğer duvarların adyabatik olduğu varsayılmaktadır. Reynolds Averaged Navier Stokes (RANS) formülasyonu, Realizable k–modeli ile birlikte türbülanslı akışları analiz etmek için kullanılmıştır. Ayrıca, ışınım transfer denklemini (RTE) çözmek için kesikli ordinatlar metodu (DOM) kullanılmıştır. Rayleigh sayısı (Ra), optik kalınlık (), Planck sayısı (Pl), saçılma albedosu () ve duvar yayma oranı ( ) parametrelerinin etkisi, akış ve sıcaklık dağılımı kapalı kare geometri içinde sayısal olarak çalışılmıştır. Türbülanslı doğal taşınım ve ışınımda parametrelerin karakterize edilmesine odaklanan detaylı bir parametrik çalışmanın nadiren ayrıntılı olarak ele alındığını belirtmek ilginçtir. Çözümler 109 ila 1012 arasında değişen Rayleigh sayısı için elde edilmiştir. Işınım ısı transferinin geometri içinde akış alanlarının özelliklerini değiştirdiği bulunmuştur. Optik kalınlığın arttırılması, sabit bir Rayleigh sayısı için birleşik ısı transferinde bir azalmaya neden olurken ve ışınımla birlikte düşük optik kalınlıkta maksimum ısı transferi elde edilmiştir. =0.2 ve 5 için sırasıyla =87.796 ve 82.351 elde edilmiştir (Ra=1010, Pl=0.02 ve =0). Isı transferi azalan Planck sayısı ile artar ve artan saçılma albedo ile azalır. Pl=0.001 ve 10 için sırasıyla =445.837 ve 68.100 bulunmuştur (Ra=1010, =1 ve =0). Aktif duvarlar siyah, yalıtılmış duvarlar yansıtıcı olduğunda, Ra=1010, Pl=0.02, =1 ve =0 için =85.507 elde edilmiştir.

Keywords

Türbülanslı doğal taşınım, RANS, Isıl ışınım, İzotropik saçılmalı ortam, Kare geometri

TURBULENT NATURAL CONVECTION AND RADIATION HEAT TRANSFER IN SQUARE ISOTROPIC SCATTERING MEDIUM

Abstract

The influence of turbulent natural convection and thermal radiation in a differentially heated square enclosure is numerically investigated. The enclosure is heated from the right wall and cooled from the left wall. The other walls are assumed to be adiabatic. The Reynolds Averaged Navier Stokes (RANS) formulation was employed for analyzing turbulent flows together with a Realizable k– model. In addition, the discrete ordinates method (DOM) was used to solve the radiative transfer equation (RTE). Influence of Rayleigh number (Ra), optical thickness (), Planck number (Pl), scattering albedo () and wall emissivity ( ) parameters were studied numerically on square enclosure for the flow and temperature distribution. It is interesting to note that a detailed parametric study focusing on characterizing parameters in turbulent natural convection and radiation was rarely dealt with in details. Solutions were obtained for a range of Rayleigh numbers varying from 109 to 1012. It was found that the radiation heat transfer alters the characteristics of flow fields in the enclosure. Increasing the optical thickness results in a decrease in combined heat transfer for a fixed Rayleigh number and the maximum of heat transfer occurred for low optical thickness with radiation presence. =87.796 and 82.351 is obtained for =0.2 and 5, respectively (Ra=1010, Pl=0.02 and =0). The heat transfer increases with decreasing Planck number, and decreases with the increasing scattering albedo. =445.837 and 68.100 is obtained for Pl=0.001 and 10, respectively (Ra=1010, =1 and =0). When the active walls are black and the insulated walls are reflected, =85.507 is obtained for Ra=1010, Pl=0.02, =1 and =0.

Keywords

Turbulent natural convection, RANS, thermal radiation, isotropic scattering medium, square enclosure

References

• Capdevila R., Lehmkuhl O., Trias F.X., Pérez-Segarra C.D. and Colomer G., 2011, Turbulent natural convection in a differentially heated cavity of aspect ratio 5 filled with non-participating and participating grey media, J Phys: Conf Series, 318: 042048.
• Capdevila R., Lehmkuhl O., Colomer G. and Perez-Segarra C.D, 2012, Study of turbulent natural convection in a tall differentially heated cavity filled with either non-participating, participating grey and participating semigrey media, J. Phys: Conf Series, 395: 1-8.
• Czarnota T. and Wagner C., 2016, Turbulent convection and thermal radiation in a cuboidal Rayleigh–Bénard cell with conductive plates, Int J Heat Fluid Fl, 57, 150–72.
• Desrayaud G. and Lauriat G., 1985, Natural convection of a radiating fluid in a vertical layer, J Heat Transf, 107, 710–2.
• Draoui A., Francis A. and Beghein C.,1991, Numerical analysis of heat transfer by natural convection and radiaition in participating fluids enclosured in square cavities, Numer. Heat Transfer, Part A, 20, 253–61.
• Fluent User’s Guide, Fluent Inc., .. USA; 2011.
• Fusegi T. and Farouk B., 1989, Laminar and turbulent natural convection-radiation interaction in a square enclosure filed with a nongray gas, Numer. Heat Transfer, Part A, 15, 303-22.
• Ibrahim A., Saury D. and Lemonnier D., 2013, Coupling of turbulent natural convection with radiation in an air-filled differentially-heated cavity at Ra = 1.5 x 109, Comput Fluids, 88, 115–25.
• Lauriat G., 1982, Combined radiation–convection in gray fluids enclosed in vertical cavities, J Heat Transf, 104, 609–15.
• Mesyngier C. and Farouk B., 1996, Turbulent natural convection-nongray gas radiation analysis in a square enclosure, Numer. Heat Transf Part A, 29, 671–87.
• Mezrhab A., Lemonnier D., Meftah S. and Benbrik A., 2008, Numerical study of double diffusion convection coupled to radiation in a square cavity filled with a participating grey gas, J Phys D: Appl Phys, 41, 195501–17.
• Miroshnichenko I.V., Sheremet M.A. and Mohamad A.A., 2016, Numerical simulation of a conjugate turbulent natural convection combined with surface thermal radiation in an enclosure with a heat source, Int J Therm Sci, 109, 172–81.
• Mondal B. and Mishra S.C., 2009, Simulation of natural convection in the presence of volumetric radiation using the lattice Boltzmann method, Numer. Heat Transfer, Part A,55, 18–41.
• Moufekkir F., Moussaoui M.A., Mezrhab A., Naji H. and Lemonnier D.,2012, Numerical prediction of heat transfer by natural convection and radiation in an enclosure filled withan isotropic scattering medium, J Quant Spectrosc Radiat Transf, 113, 1689-1704.
• Moufekkir F., Moussaoui M.A., Mezrhab A., Lemonnier D. and Naji H., 2012, MRT-lattice Boltzmann computations of natural convection and volumetric radiation in a tilted square enclosure, Int J Therm Sci, 54, 124-141.
• Salat J., Xin S., Joubert P., Sergent A., Penot F. and Quéré P.L., 2004, Experimental and numerical investigation of turbulent natural convection in a large air-filled cavity, Int J Heat Fluid Fl, 25, 824–32.
• Sergent A., Xin S., Joubert P., Quéré P.L., Salat J. and Penot F., 2013, Resolving the stratification discrepancy of turbulent natural convection in differentially heated air-filled cavities – Part I: reference solutions using Chebyshev spectral methods, Int J Heat Fluid Fl, 39, 1–14.
• Sharma A.K, Velusamy K., Balaji C. and Venkateshan S.P., 2007, Conjugate turbulent natural convection with surface radiation in air filled rectangular enclosures, Int J Heat Mass Transf, 50, 625–39.
• Sharma A,K., Velusamy K. and Balaji C., 2008, Interaction of turbulent natural convection and surface thermal radiation in inclined square enclosures, Heat Mass Transf, 44, 1153–70.
• Shati A.K.A, Blakey S.G. and Beck S.B.M., 2012, A dimensionless solution to radiation and turbulent natural convection in square and rectangular enclosures, J Eng Sci Techn, 7 (2), 257–79.
• Sheremet M,A. and Miroshnichenko I.V, 2015, Numerical study of turbulent natural convection in a cube having finite thickness heat-conducting walls, Heat Mass Transf, 51, 1559–69.
• Soucasse L., Riviere P., Soufiani A., Xin S. and Quéré P.L., 2014, Transitional regimes of natural convection in a differentially heated cubical cavity under the effects of wall and molecular gas radiation, Phys. Fluids, 26, 024105-1–23.
• Tan Z. and Howell J.R., 1991, Combined radiation and natural convection in a square enclosure with participating medium, Int J Heat Mass Transf, 34, 79–97.
• Velusamy K., Sundararajan T. and Seetharamu K.N., 2001, Interaction effects between surface radiation and turbulent natural convection in square and rectangular enclosures, J Heat Transf, 123 (6), 1062–70.
• Webb B.W. and Viskanta R., 1987, Radiation-induced buoyancy driven flow in rectangular enclosures: Experiment and analysis, J Heat Transf, 109, 427–33.
• Wu T. and Lei C., 2015, On numerical modelling of conjugate turbulent natural convection and radiation in differentially heated cavity, Int J Heat Mass Transf, 91, 454–66.
• Xamán J., Arce J., Álvarez G. and Chávez Y., 2008, Laminar and turbulent natural convection combined with surface thermal radiation in a square cavity with a glass wall, Int J Therm Sci, 47, 1630–8.
• Xin S., Salat J., Joubert P., Sergent A., Penot F. and, Quéré P.L., 2013, Resolving the stratification discrepancy of turbulent natural convection in differentially heated air-filled cavities. Part III: a full convection–conduction–surface radiation coupling, Int J Heat Fluid Fl, 42, 33–48.
• Yucel A. and Acharya S., and Williams M.L., 1989, Natural convection and radiation in a square enclosure, Numer. Heat Transfer, Part A, 15, 261–78.
• Yucel A. and Acharya S., and Williams M.L., 1994, Natural convection of a radiating fluid in square enclosure with perfectly conducting end walls, Sadhana, 519, 751–64.