Erhan FIRAT

Tek Taraflı Isıtmaya Maruz Yüksek Şekil Oranlı Minikanallarda Pasif Akış Kontrol Yöntemi Kullanılarak Isı Transferinin İyileştirilmesi

Pasif akış kontrol silindirinin olduğu ve olmadığı durumlarda, bir geniş yüzeyinden ısıtılan dar, dikdörtgen şeklindeki bir minikanal içerisindeki taşınımla ısı transferi durumunun hesaplamalı akışkanlar dinamiği (HAD) benzetiminin sonuçları rapor edilmiştir. Silindirin çapı (d), kanal yüksekliğinin (t) yaklaşık olarak onda biri kadardır. Bu çalışmanın amacı, ısıtılan kanal duvarı ve silindirin merkezi arasındaki üç farklı mesafeyi (s) çalışarak, pasif kontrol silindirinin sistemin ısıl performansı üzerindeki etkisini anlamaktır. Test edilen boyutsuz mesafelere (s/t) bakılmaksızın, pasif kontrol silindirinin mevcudiyetinde sistemin ısıl performansının iyileştiği bulunmuştur. Bu, üniform ısı akısına maruz kalan yüzey üzerindeki hidrodinamik sınır tabaka ile sırayla büyük-ölçekli çevrilere dökülen, silindirden olan serbest kayma tabakalarının şiddetli etkileşimlerine dayandırılmıştır.

Anahtar Kelimeler:

Isı transferi iyileştirilmesi, Pasif akış kontrolü, Minikanal, HAD

Heat Transfer Enhancement in a High Aspect Ratio Minichannel Heated on one Side Using a Passive Flow Control Method

The results of computational fluid dynamics (CFD) simulation for convective heat transfer in a narrow rectangular minichannel heated on one large side, with and without the presence of passive flow control cylinder, are reported. The diameter of the cylinder (d) is approximately one tenth of the height of the channel (t). The objective of this study is to understand the effect of the passive control cylinder on thermal performance of the system by studying three different distances (s) between the heated channel wall and the center of the cylinder. It was found that the thermal performance of the system enhanced in the presence of the passive control cylinder regardless of non-dimensional distances (s/t) tested. This was attributed to the strong interactions between free shear layers from the cylinder that alternately shed largescale vortices and hydrodynamic boundary layer on the surface that is subjected to a uniform heat flux.

Keywords:

Heat transfer enhancement, Passive flow control, Minichannel, CFD,

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