NUMERICAL ANALYSIS OF COMBINED NATURAL CONVECTION AND RADIATION IN A SQUARE ENCLOSURE PARTIALLY HEATED VERTICAL WALL

Gri duvarlı içi hava dolu kare geometride doğal taşınım ve ısıl ışınım ısı transferi sabit sıcaklık farkına sahip üç farklı durum için sayısal olarak incelenmiştir. Kısmi olarak ısıtılmış sol duvar ve soğuk sağ duvar sabit sıcaklıkta muzafaza edilmiş diğer duvarlar yalıtılmıştır. Isı kaynağından diğer yüzeylere ışınımla ısı transferi olduğu göz önüne alınmış ve ortamın katılımcı olmadığı kabul edilmiştir. Duvarların ışınım yayma oranlarının aynı olduğu düşünülmüştür. Boussinesq yaklaşımı ile beraber taşınım denklemleri ve enerji denklemi FLUENT yazılımı ile çözülmüştür. Sürekli rejimde, yüzey ışınım yayma oranı değiştirilirken, her durum için soğuk plaka yüzey alanı üzerinden hesaplanan ortalama Nusselt sayısı Rayleigh sayısının fonksiyonu olarak hesaplanmıştır. Bu çalışmada, Rayleigh sayısı 105 ile 107 arasında değiştirilirken, yüzey ışınım yayma oranları ε=0 ile 1 arasında değiştirilmiştir. Isı transferi ve akışkan akış karakteristikleri iletim-ışınım parametresi, Rayleigh sayısı ve duvar ışınım yayma oranı etkisi açısından incelenmiştir

KISMİ OLARAK DİKEY DUVARINDAN ISITILMIŞ KAPALI KARE GEOMETRİDE BİRLEŞİK DOĞAL TAŞINIM VE IŞINIMIN SAYISAL İNCELENMESİ

Combined natural convection and thermal radiation heat transfer in air-filled square gray enclosure are numerically investigated for three different cases having the same constant temperature difference. The partially heated patch of the left wall and the cold right wall are maintained at constant temperatures while the other walls are insulated. The surface radiation heat transfer is considered from the heat sources (patch) to the other surfaces, and the medium is assumed to be nonparticipating. The emissivity ratio of the walls are kept the same. The transport equations along with Boussinesq approximation as well as the energy equation are solved using FLUENT software. As the wall emissivities were changed, the steady state mean Nusselt numbers over the cold surface were computed for each case as a function of the Rayleigh number. In this study, the Rayleigh number was ranged from 105 to 107 while the surface emissivity ratio was changed from ε=0 to 1. The heat transfer and fluid flow characteristics were investigated with respect to the effect of the conduction-radiation parameter, Rayleigh number and the wall emissivity.

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