Düz bir levhaya çarpan sınırlandırılmamış ve sınırlandırılmış dairesel hava jetlerinde ısı transferi etkilerinin incelenmesi

Yıl 2023, , 1325 - 1334, 15.10.2023

Haluk Keleş , Yücel Özmen

https://doi.org/10.28948/ngumuh.1310010

Öz

Bu çalışmada, düz bir yüzeye çarpan sınırlandırılmamış ve sınırlandırılmış türbülanslı dairesel hava jetlerinde çarpma yüzeylerindeki ısı transferi etkileri deneysel olarak incelenmiştir. Çarpma levhası yüzeylerinde termal kamera ile gerçekleştirilen sıcaklık ölçümlerinden, çarpma levhası orta ekseni boyunca sıcaklık dağılımları elde edilmiştir. Elde edilen sıcaklık dağılımlarından, Reynolds sayısının, lüle-levha arası açıklığın ve sınırlayıcı levha durumunun çarpma levhası üzerindeki Nusselt dağılımlarına etkisi araştırılmıştır. İncelenen tüm akış alanlarında, çarpma levhası üzerindeki Nusselt değerlerinin artan Reynolds sayısı ile arttığı, artan lüle-levha arası açıklık ile azaldığı görülmüştür. Akış alanlarında sınırlayıcı levhanın varlığı, çarpma levhası üzerindeki Nusselt değerlerini azaltmaktadır. Sınırlandırılmamış jet durumunda çarpma bölgesindeki Nusselt değerleri sınırlandırılmış jet durumuna kıyasla % 15’e varan oranda daha yüksek elde edilmiştir.

Anahtar Kelimeler

Çarpan dairesel jet, Sınırlayıcı levha, Nusselt dağılımı

Investigation of effects of heat transfer in unconfined and confined impinging circular air jets on flat plate

Öz

In this study, the heat transfer effects on the impingement surfaces of unconfined and confined turbulent circular air jets impinging a flat surface are investigated experimentally. Temperature distributions along the center axis of the impingement plate were obtained from the temperature measurements performed with a thermal camera on the impingement plate surfaces. From the obtained temperature distributions, the effects of Reynolds number, nozzle-to-plate spacing, and the presence of confinement plate on the Nusselt distributions on the impingement plate were investigated. In all flow fields investigated, it was observed that the Nusselt values on the impingement plate increased with increasing Reynolds number and decreased with increasing nozzle-to-plate spacing. The presence of the confinement plate in the flow fields reduces the Nusselt values on the impingement plate. In the unconfined jet case, the Nusselt values in the impingement region were up to 15 % higher than in the confined jet case.

Anahtar Kelimeler

Impinging circular jet, Confinement plate, Nusselt distribution

Kaynakça

• C. J. Danek, Heat transfer under impinging jets at very close jet-to-target spacings. PhD Thesis, Stanford University, Ann Arbor, USA, 1995.
• H. Schrader, Trocknung feuchter oberfiachen mittels warmluft- stralen. VDI Forschungsheft Ausgabe, 484, B 27, 1961.
• C. M. Ho, Local and global dynamics of free shear layers. Numerical and Physical Aspects of Aerodynamic Flows, 521-533, 1982. https://doi.org/10.1007/978-3-662-12610-3_30.
• R. J. Goldstein, K.A. Sobolik, and W.S. Seol, Effect of entrainment on the heat transfer to a heated circular air jet ımpinging on a flat surface. Journal of Heat Transfer. 112(3), 608-611, 1990. https://doi.org/10.1115/1.2910430.
• J. W. Baughn and S. Shimizu, Heat transfer measurements from a surface with uniform heat flux and an impinging jet, Journal of Heat Transfer. 111(4), 1096-1098, 1989. https://doi.org/10.1115/1.3250776.
• A. K. Mohanty and A.A. Tawfek, Heat transfer due to a round jet impinging normal to a flat surface. International Journal of Heat and Mass Transfer, 36(6), 1639-1647, 1993. https://doi.org/10.1016/S0017-9310(05)80073-0.
• L. Huang and M.S. El-Genk, Heat transfer of an ımpinging jet on a flat surface. International Journal of Heat and Mass Transfer, 37(13), 1915-1923, 1994. https://doi.org/10.1016/0017-9310(94)90331-X.
• D. Lytle and B.W. Webb, Air jet impingement heat transfer at low nozzle-plate spacings. International Journal of Heat and Mass Transfer, 37(12), 1687-1697, 1994. https://doi.org/10.1016/0017-9310(94)90059-0.
• D. W. Colucci and R. Viskanta, Effect of nozzle geometry on local convective heat transfer to a confined impinging air jet. Experimental Thermal and Fluid Science, 13(1), 71-80, 1996. https://doi.org/10.1016/0894-1777(96)00015-5.
• Y. Ozmen and E. Baydar, Flow structure and heat transfer characteristics of an unconfined ımpinging air jet at high jet reynolds numbers. Heat and Mass Transfer, 44(11), 1315-1322, 2008. https://doi.org/10.1007/s00231-008-0378-4.
• R. Herrero and J.M. Buchlin, Effect of nozzle shape on local heat transfer distribution in impinging jets. 10th International Conference on Quantitative InfraRed Thermography, Quebec, Canada, 27-30 July 2010. http://dx.doi.org/10.21611/qirt.2010.054
• T. T. Chandratilleke, R. Narayanaswamy and D. Jagannatha, Thermal performance evaluation of a synthetic jet heat sink for electronic cooling. IEEE 13th Electronics Packaging Technology Conference, Singapore, pp. 79-83, 2011. https://10.1109/EPTC.2011.6184390.
• X. Ai, Z.G. Xu and C.Y. Zhao, Experimental study on heat transfer of jet impingement with a moving nozzle. Applied Thermal Engineering, c. 115, pp. 682-691, 2017. https://doi.org/10.1016/j.applthermaleng.2017.01.004.
• M. Gradeck, A. Kouachi, A. Dani, D. Arnoult and J.L. Boréan, Experimental and numerical study of the hydraulic jump of an impinging jet on a moving surface. Experimental Thermal and Fluid Science, c. 30, 193-201, 2006. https://doi.org/10.1016/j.expthermflusci.2005.05.006.
• M. K. Sevindir, Çapraz Akış İçerisinde Sıcak Jet Akışının Sayısal ve Deneysel İncelenmesi. Doktora Tezi, Y.T.Ü., Fen Bilimleri Enstitüsü, İstanbul, Türkiye, 2007.
• J. M. Miranda and J.B.L.M. Campos, Impinging jets confined by a conical wall: Laminar flow predictions. AIChE Journal of Fluid Mechanics and Transport Phenomena, c. 45, 2273-2285, 1999. https://doi.org/10.1002/aic.690451103.
• M. Behnia, S. Parneix, Y. Shabany and P.A. Durbin, Numerical study of turbulent heat transfer in confined and unconfined impinging jets. International Journal of Heat and Fluid Flow, c. 20, 1-9, 1999. https://doi.org/10.1016/S0142-727X(98)10040-1.
• L. Huang, Heat transfer and flow visualization of conventional and swirling impinging jets. PhD Thesis, New Mexico University, Albuquerque, New Mexico, 1996.
• T. L. Bergman, A.S. Lavine, F.P. Incropera and D.P. Dewitt, Introduction to Heat Transfer. Wiley, Sixth Edition. New Jersey, ABD, 2011.
• S. W. Churchill and H.H.S. Chu, Correlating equations for laminar and turbulent free convection from a vertical plate. International Journal of Heat and Mass Transfer, 18, 1323-1329, 1975. https://doi.org/10.1016/0017-9310(75)90243-4.
• S. Kline and F. Mcclintock, Describing uncertainties in single-sample experiments, Mechanical Engineering, 75, 3-8, 1953.
• A. Ianiro and G. Cardone, Heat transfer rate and uniformity in multichannel swirling impinging jets. Applied Thermal Engineering, 49, 89-98, 2012. https://doi.org/10.1016/j.applthermaleng.2011.10.018.
• L. Xu, T. Yang, Y. Sun, L. Xi, J. Gao, Y. Li and J. Li, Flow and heat transfer characteristics of a swirling impinging jet issuing from a threaded nozzle. Case Studies in Thermal Engineering, 25, 2021. https://doi.org/10.1016/j.csite.2021.100970.