Browsing by Author "Yesildal, Faruk"

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Experimental and Numerical Investigations of Impingement Air Jet for a Heat Sink
(Elsevier Science Bv, 2016) Yakut, Ridvan; Yakut, Kenan; Yesildal, Faruk; Karabey, Altug
In this study, impingement air jet heat and flow characteristics of hexagonal finned heat sink which was named as OHS-2 were determined experimentally and analysed numerically by Ansys-Fluent CFD programme. The heat sink was optimized by using Taguchi method in the wind tunnel according to L-18(2(1)x3(7)) orthogonal array in earlier study [1]. Therefore, the optimized heat sink was used instead of another heat sink. Six of most commonly used turbulence models in the numerical analysis of heat and mass transfer with impinging jets were examined and k-epsilon reliable turbulence model was chosen the most suitable for experimental study. The experimental and numerical studies were carried out for a heat sink with a nozzle diameter, two different Y/d distances, 6 different flow rates and 3 different fin heights. The variations of the Nu-Re and Cp-x,Cp-y-l/(l(0)/2) were analysed and compared. Finally, heat transfer correlations were produced from experimental and numerical results of impingement jet heat transfer. Also the numerical and experimental results were observed to be in a good agreement. (C) 2016 The Authors. Published by Elsevier Ltd.
Numerical Analysis With Experimental Comparison in Duct Flow Using Optimized Heat Sinks
(Taylor & Francis Ltd, 2018) Guresci, Kumru; Yesildal, Faruk; Karabey, Altug; Yakut, Ridvan; Yakut, Kenan
In many industrial applications, heat must be transferred in the form of either an energy input into the system or removal of energy produced in the system. In this study, heat transfer and flow characteristics of hexagonal finned heat sinks which optimized according to the Taguchi experimental L-18(2(1)*3(7)) design method in channel flow was analyzed numerically. Ansys-Fluent Icepak module was used in CFD analysis. The analysis carried out for two hexagonal finned optimized heat sinks in 3 different fin heights and 5 different flow velocities. Nusselt number increased with increasing Reynolds number for OH-1 and OH-2 heat sinks with all fin heights. Also, results showed that the friction factor decreased with increasing Reynolds number for all fin heights. According to CFD results, Nu-Re and f-Re variations were obtained and compared with experimental results. The experimental results and the numerical results were quite consistent. (c) 2017 The Egyptian Society of Radiation Sciences and Applications. Production and hosting by Elsevier B.V.
Pestisit Uygulamaları İçin Optimize Edilmiş Koşullarda Sprey Karakteristiklerinin Belirlenmesi
(2020) Sayıncı, Bahadır; Özkan, Yunus; Karabey, Altuğ; Yesildal, Faruk
Tarım küresel bazda gelişmekte olan büyük ve ciddi bir sektördür. Tarımda önemli bir araştırma konusu püskürtmeyöntemiyle yapılan pestisit uygulamalarıdır. Sprey uygulama teknolojilerinin amaçlarından biri, bitkisel üretimde zararlıveya hastalık etmenlerinin seviyesini azaltmak için pestisitlerin doğru zamanda uygun tekniklerle önerilen dozdakullanılmasını sağlamaktır. Bu çalışmada, konvansiyonel pülverizatörlerde kullanılan ve tek noktadan atomizasyonsağlayan konik hüzmeli nozulun akış parametrelerinin damlacık çapı üzerindeki etkileri incelenmiştir. Bu amaçdoğrultusunda, sabit ilaçlama hızı ve spreyleme açısı koşullarında üç farklı nozul-yüzey mesafesi (70 cm, 85 cm, 100cm), üç farklı işletme basıncı (6 bar, 8 bar, 10 bar) ve üç farklı nozul çapı akış parametreleri olarak belirlenmiştir.Deneyler farklı zamanlarda çift tekrarlı olarak yapılmıştır. Sprey uygulamalarından sonra suya duyarlı kağıtlarınyüzeyinden elde edilen damla lekesi görüntüleri işlenerek hacimsel çap ve damla homojenlik değerleri belirlenmiştir.Akış parametrelerinin damla çapına olan etkisini incelemek için grafikler çizilmiş ve değişimler yorumlanmıştır. Genelolarak, aynı nozul orifis çapı ve spreyleme mesafesinde; işletme basıncı artarken karakteristik damla çapları küçülmüşve homojenlik katsayısı iyileşmiştir. Aynı işletme basıncı ve spreyleme mesafesi için nozul orifis çaplarıkarşılaştırıldığında; orifis çapı arttıkça damlacık çapının arttığı ve homojenliğin azaldığı gözlemlenmiştir.
Thermal Performance Analysis of Optimized Hexagonal Finned Heat Sinks in Impinging Air Jet
(Amer inst Physics, 2016) Yakut, Kenan; Yesildal, Faruk; Karabey, Altug; Yakut, Ridvan
In this study, thermal performance analysis of hexagonal finned heat sinks which optimized according to the experimental design and optimization method of Taguchi were investigated. Experiments of air jet impingement on heated hexagonal finned heat sinks were carried out adhering to the L-18(2(1)*3(6)) orthogonal array test plan. Optimum geometries were determined and named OH-1, OH-2.. Enhancement efficiency with the first law of thermodynamics was analyzed for optimized heat sinks with 100, 150, 200 mm heights of hexagonal fin. Nusselt correlations were found out and variations of enhancement efficiency with Reynolds number presented in eta-Re graphics.