The Influence of Bottom Geometry on Turbulent Flow Field in a Lid-Driven Cavity

Öz

In this study, the effect of rib structures on the turbulent flow and heat transfer have been investigated numerically. six different Reynolds Numbers, two different rib geometry (sharp-edged square and rounded-edged square) and four different rib layout are carried out. Streamlines close to  the ribbed area, velocities, temperature distributions and Nusselt Number distributions on the bottom surface are investigated.

The results shows that, flow near the  bottom surface behaves independently by the reason of small stable vortices arises among the little cavities between the rib geometries and this hydrodynamic field created by the bottom geometry has significant effects on heat transfer. Besides, it is found that, for all Reynolds numbers,  the total heat transfer coefficient is prominently influenced in case of sharp edged square rib cross section, and most reduction on the heat transfer is observed in this case. The reduction in the total heat transfer coefficient in a given Reynolds number range has reached 25%.

Anahtar Kelimeler

• Lid driven cavity flow,Computational Fluid Dynamics (CFD),heat transfer,ribbed surfaces

Kapak Etkili Hücre İçindeki Türbülanslı Akıma Taban Geometrisinin Etkisi

Öz

Üç boyutlu hücre tabanındaki çıkıntıların (rib), hücre içindeki türbülanslı akıma ve ısı transferine etkisi sayısal olarak incelenmiştir. Çalışmada altı farklı Reynolds sayısı, iki farklı çıkıntı geometrisi ( kare ve köşeleri yuvarlatılmış kare) ve dört farklı yerleşim kullanılmıştır. Çıkıntı bölgelerindeki akım çizgileri, hız alanları, sıcaklık dağılımları ile birlikte Nusselt sayısının alt yüzeydeki değerleri ve değişimi incelenmiştir.

Çıkıntıların oluşturduğu hücrecikler içerisindeki küçük girdaplar nedeniyle taban yakınındaki akımın hücre içindeki ana akımdan büyük oranda bağımsız davranış gösterdiği ve taban geometrisinin ortaya çıkardığı hidrodinamik yapının ısı transferi üzerinde etkili olduğu görülmüştür. Toplam ısı transfer katsayısının bütün Reynolds sayılarında keskin köşeli kare kesitli çıkıntı geometrisi ve rib yükseklik genişlik oranının eşit olması durumundan belirgin şekilde etkilendiği ve ısı transferinin en fazla bu durumda azaldığı görülmüştür. Belirli bir Reynolds sayısı aralığında toplam ısı transfer katsayısındaki azalma %25 mertebelerine ulaşmıştır.

Anahtar Kelimeler

• Kapak etkili hücre,Hesaplamalı Akışkanlar Dinamiği (HAD),ısı transferi,çıkıntılı yüzeyler

Kaynakça

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