Browsing by Author "Arslan, Kamil"

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Comparison of Different Turbulent Models in Turbulent-Forced Convective Flow and Heat Transfer Inside Rectangular Cross-Sectioned Duct Heating At the Bottom Wall
(Progress in Exergy, Energy, and the Environment, 2014) Onur, Nevzat; Onur, Nevzat; 53858
In this study, steady-state turbulent-forced flow and heat transfer in a horizontal smooth rectangular cross-sectioned duct was numerically investigated. The study was carried out in the turbulent flow region where Reynolds number ranges from 1 × 104 to 5 × 104. The flow was developing both hydrodynamically and thermally. The bottom surface of the duct was assumed to be under constant surface temperature. A commercial CFD program Ansys Fluent 12.1 with different turbulent models was used to carry out the numerical study. Different turbulence models (k–ε Standard, k–ε Realizable, k–ε RNG, k–ω Standard and k–ω SST) were used. Based on the present numerical solutions, new engineering correlations were presented for the heat transfer and friction coefficients. The numerical results for different turbulence models were compared with each other and the experimental data available in the literature. It was observed that k–ε turbulence models represented the turbulent flow condition very well for the present study.
Experimental and numerical investigation of transition to turbulent flow and heat transfer inside a horizontal smooth rectangular duct under uniform bottom surface temperature
(Springer, 2013) Onur, Nevzat; Arslan, Kamil; 47465; 53858
In this study, steady-state turbulent forced flow and heat transfer in a horizontal smooth rectangular duct both experimentally and numerically investigated. The study was carried out in the transition to turbulence region where Reynolds numbers range from 2,323 to 9,899. Flow is hydrodynamically and thermally developing (simultaneously developing flow) under uniform bottom surface temperature condition. A commercial CFD program Ansys Fluent 12.1 with different turbulent models was used to carry out the numerical study. Based on the present experimental data and three-dimensional numerical solutions, new engineering correlations were presented for the heat transfer and friction coefficients in the form of and , respectively. The results have shown that as the Reynolds number increases heat transfer coefficient increases but Darcy friction factor decreases. It is seen that there is a good agreement between the present experimental and numerical results. Examination of heat and mass transfer in rectangular cross-sectioned duct for different duct aspect ratio (alpha) was also carried out in this study. Average Nusselt number and average Darcy friction factor were expressed with graphics and correlations for different duct aspect ratios.
Experimental investigation of flow and heat transfer in rectangular cross-sectioned duct with baffles mounted on the bottom surface with different inclination angles
(Springer, 2014) Onur, Nevzat; Onur, Nevzat; 47465; 53858
In this study, steady-state forced convection heat transfer and pressure drop characteristics in a horizontal rectangular cross-sectioned duct, baffles mounted on the bottom surface with different inclination angles were investigated experimentally in the Reynolds number range from 1 x 10(3) to 1 x 10(4). The study was performed under turbulent flow conditions. Effects of different baffle inclination angles on flow and heat transfer were studied. Results are also presented in terms of thermal enhancement factor. It is observed that increasing in baffle inclination angle enhances the heat transfer and causes an increase in pressure drop in the duct.
Experimental investigation of laminar heat transfer inside trapezoidal duct having different corner angles
(Taylor&Francis INC, 2015) Onur, Nevzat; Arslan, Kamil; 53858
In this study, steady-state laminar forced flow and heat transfer in a horizontal smooth trapezoidal duct having different corner angles were experimentally investigated in the Reynolds number range from 10(2) to 10(3). Flow is hydrodynamically fully developed and thermally developing under a uniform surface temperature condition. Based on the present experimental data of laminar flow in the thermal entrance region, new engineering correlations were presented for the heat transfer and friction coefficients for each corner angle. The results have shown that as the Reynolds number increases heat transfer coefficient increases but Darcy friction factor decreases. Also, it is observed that average Nusselt number increases while average Darcy friction factor decreases with increasing corner angle of the duct.
R 236fa Kullanılan Bir Ejektör İçerisindeki Türbülanslı Akış ve Isı Transferinin Sayısal Olarak İncelenmesi
(2014) Onur, Nevzat; Arslan, Kamil; Mulcar, Hasan; Onur, Nevzat
Yamuk kesitli kanal içerisinde hidrodinamik olarak tam gelişmiş ısıl olarak gelişmekte olan laminer akış ve ısı transferinin sayısal olarak incelenmesi
(Çankaya Üniversitesi, 2012) Onur, Nevzat; Arslan, Kamil; Turgut, Oğuz; 53858; 47465; 46131
Bu çalışmada yamuk kesit alanına sahip bir kanal içerisindeki hidrodinamik olarak tam gelişmiş ısıl olarak gelişmekte olan üç boyutlu zorlanmış konveksiyon akış ve ısı transferi kararlı rejim ve sabit yüzey sıcaklığı şartlarında sayısal olarak incelenmiştir. Sayısal çalışma Reynolds sayısının 100 ≤ Re ≤ 1000 aralığında gerçekleştirilmiştir. Ç alışma akışkanı olarak hava (P r ∼= 0.7) kullanılmıştır. Sayısal çalışmanın gerçekleştirilebilmesi için ticari Sayısal Akışkanlar Dinamiği yazılımı olan Ansys Fluent 12.1 paket programı kullanılmıştır. Ortalama Nusselt sayıları ve ortalama Darcy sürtünme faktörleri farklı Reynolds sayıları için sunulmuştur. Yerel Nusselt sayıları kanal boyunca mesafenin fonksiyonu olarak çizilmiştir. Hız ve sıcaklık dağılımları kanal boyunca farklı pozisyonlarda grafiksel olarak verilmiştir. Ç alışmadan elde edilen sonuçlar literatürde yapılmış olan benzer çalışmalar ile kıyaslanmış ve sonuçların literatür ile uyum içerisinde olduğu saptanmıştır. Reynolds sayısındaki artışın ısı transferinde artışa ve sürtünme faktöründe azalışa neden olduğu görülmüştür. Yamuk kesitli kanal içerisindeki laminer akışta hidrodinamik ve ısıl olarak tam gelişmiş şartlardaki Nusselt sayısı değerinin 2.95 olduğu belirlenmiştir. Sayısal çalışmanın sonucunda, ısı transferi ve sürtünme faktörü değerleri için yeni korelasyonlar elde edilmiştir.