TÜRBÜLATÖR İÇEREN KISMİ DALGALI BİR KANALDA TÜRBÜLANSLI ISI TRANSFER ANALİZİ

Abstract

Bu çalışma, dairesel türbülatör içeren kısmi dalgalı bir kanalda türbülanslı ısı transferini sayısal olarak araştırmaktadır. Simülasyonlar, ANSYS Fluent programı kullanılarak gerçekleştirilir. Kanalın giriş ve çıkış bölümleri düz ve adyabatiktir. Kanalın ortasında dairesel türbülatör içeren kısmi dalgalı bir bölüm mevcuttur. Dalgalı yüzeyler q″ = 2000 W/m2 sabit ısı akısında tutulmaktadır. Çalışmada iş yapan akışkan havadır. Viskoz model olarak standart k-ε türbülans modeli kullanılmıştır. Reynolds sayısı 3000≤Re≤6000 aralığında değişmiştir. Farklı Reynolds sayılarında, türbülatörlü ve türbülatörsüz durum için çıkış sıcaklığı, yüzey sıcaklığı, ısı transfer katsayısı, Nusselt sayısı, basınç düşüşü, sürtünme faktörü ve termohidrolik performans hesaplanmıştır. Kanalda dairesel türbülatörün hız ve sıcaklık dağılımları üzerindeki etkisi paylaşılmıştır. Elde edilen bulgular, Re artması ile çıkış sıcaklığının, yüzey sıcaklığının ve sürtünme katsayısının düştüğünü göstermiştir. Bunun yanında, Re artması, ısı transfer katsayısını, Nusselt sayısını ve basınç düşüşünü artırmıştır. Türbülatörlü kanalda ısı transferi ve basınç düşüşü türbülatörün olmadığı kanala göre daha yüksektir. En yüksek Nusselt sayısı, Re=6000 ve türbülatörlü durumda Nu=55,81 olarak hesaplanmıştır. Re=6000’de türbülatörlü kanalda ısı transferi türbülatörsüz kanala göre %15 iyileşmiş ancak basınç düşüşü biraz artış göstermiştir. En yüksek THP, Re=5000’te türbülatörlü kanalda 1,041 olarak elde edilmiştir.

Keywords

• Kısmi dalgalı kanal
• Dairesel türbülatör
• Isı transferi iyileştirme
• Sayısal çalışma

ANALYSIS OF TURBULENT HEAT TRANSFER IN A PARTIALLY WAVY CHANNEL WITH TURBULATOR

Abstract

This study numerically examined turbulent heat transfer in a partially wavy channel containing a circular turbulator. The simulations are performed using the ANSYS Fluent program. The inlet and outlet surfaces of the channel are flat and adiabatic. A partially wavy section containing a circular turbulator exists in the middle of the channel. The wavy surfaces are maintained at a constant heat flux q″ = 2000 W/m². The working fluid in this study is air. The standard k-ε turbulence model was used as the viscous model. The Reynolds number varied in the range of 3000 ≤ Re ≤ 6000. For different Reynolds numbers, the outlet temperature, surface temperature, heat transfer coefficient, Nusselt number, pressure drop, friction factor and thermohydraulic performance were calculated for both the with/without turbulator cases. The effect of the circular turbulator on velocity and temperature distributions in the channel is shared. The findings show that as the Re increases, the outlet temperature, surface temperature, and friction coefficient decrease. In addition, increasing the Re increased the heat transfer coefficient, Nusselt number, and pressure drop. In the channel containing turbulator, heat transfer and pressure drop were higher than in the channel without turbulator. The highest Nusselt number was calculated as Nu = 55.81 at Re = 6000 and in the channel with turbulator. At Re = 6000, heat transfer in the channel with turbulator improved by 15% compared to the channel without turbulator, but the pressure drop increased slightly. The highest THP was obtained as 1.041 at Re=5000 in the channel with turbulator.

Keywords

• Partially wavy channel
• Circular turbulator
• Heat transfer enhancement
• Numerical study

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