Enhancing Heat Transfer in Turbulent Channel Flows: A Numerical Study on the Geometric and Orientational Effects of Delta, Trapezoidal, and Rectangular Winglet Vortex Generators

Year 2026, Volume: 13 Issue: 1 , 11 - 28 , 31.03.2026

Atila Abir İğci

https://doi.org/10.17350/HJSE19030000369

https://izlik.org/JA38NP45AE

Abstract

This paper presents a numerical study on the enhancement of heat transfer in a solar air heater (SAH) duct using winglet-type longitudinal vortex generators (WLVGs). Delta (DW), trapezoidal (TW1, TW2), and rectangular (RW) winglets are examined in pointing-up (PU) and pointing-down (PD) orientations, with the span-wise spacing ratio (S/H) varied to determine the optimal layout (S/H = 1.43, b/H = 0.50). Computational Fluid Dynamics (CFD) simulations using the GEKO turbulence model in ANSYS Fluent are performed for Reynolds numbers (Re) ranging from 5,000 to 22,500. Flow structures are analysed via Q-criterion isosurfaces, Nusselt number distributions, and streamwise vorticity contours. Results show that PU orientations generally outperform PD due to closer vortex–wall interaction. The RW configuration exhibits the highest Nusselt number, achieving a maximum Nusselt number of 114.37 at Re = 22,500, primarily attributed to the persistence of its generated vortices. However, it also results in the greatest frictional penalty, with a maximum friction factor of 0.1562 at Re = 5,000 and a corresponding normalized value of 𝑓/𝑓₀ = 5.21 at Re = 22,500. Consequently, the RW configuration yields the lowest thermal enhancement factor (TEF) at high Reynolds numbers, reaching a minimum value of 1.050 at Re = 22,500, despite its strong heat transfer rate. In contrast, the highest TEF is achieved with the PU TW1 configuration (TEF = 1.473 at Re = 5,000), which offers the most favourable balance between enhanced heat transfer and acceptable frictional losses. These results provide design-oriented implications for solar air heater (SAH) systems, identifying PU TW1 as the most energy-efficient configuration, whereas RW may be more suitable for applications where maximizing heat transfer rate is prioritised over minimising frictional losses.

Keywords

Heat transfer enhancement , Numerical investigation , Solar air heater , Winglet-Type Longitudinal Vortex Generator , GEKO Turbulence model

Türbülanslı Kanal Akışlarında Isı Transferinin İyileştirilmesi: Delta, Trapez ve Dikdörtgen Kanatçık Tipi Vorteks Üreteçlerinin Geometrik ve Yönlenme Etkilerine İlişkin Sayısal Bir İnceleme

https://izlik.org/JA38NP45AE

Abstract

Bu çalışma, kanatçık tipli boyuna girdap üreticileri (WLVG) kullanılarak bir güneş hava ısıtıcısı (SAH) kanalında ısı transferinin iyileştirilmesine yönelik sayısal bir araştırmayı sunmaktadır. Delta (DW), trapezoidal (TW1, TW2) ve dikdörtgen (RW) kanatçıklar, akış-yukarı yönelimli (PU) ve akış-aşağı yönelimli (PD) konumlarda incelenmiş, en uygun yerleşimi belirlemek amacıyla kanatçıklar arası yatay aralık oranı (S/H) değiştirilmiştir (S/H = 1.43, b/H = 0.50). Sayısal akışkanlar dinamiği (CFD) simülasyonları, ANSYS Fluent yazılımında GEKO türbülans modeli kullanılarak, Reynolds sayısı (Re) 5.000 ile 22.500 aralığında gerçekleştirilmiştir. Akış yapıları, Q-kriteri eşyüzeyleri, Nusselt sayısı dağılımları ve akış yönündeki vortisite konturları aracılığıyla analiz edilmiştir. Sonuçlar, PU konumlarının, vortekslerin ısıtılan duvara daha yakın seyretmesi nedeniyle PD konumlarına kıyasla genellikle daha iyi performans gösterdiğini ortaya koymaktadır. RW konfigürasyonu, üretilen vortekslerin uzun süreli kararlılığı sayesinde en yüksek Nusselt sayısını sağlamış (Re = 22.500’de Nu = 114.37) ancak aynı zamanda en yüksek sürtünme kaybına da yol açmıştır (Re = 5.000’de 𝑓 = 0.1562 ve Re = 22.500’de normalize değer 𝑓/𝑓₀ = 5.21). Bu nedenle, RW konfigürasyonu güçlü ısı transfer oranına rağmen yüksek Reynolds sayılarında en düşük termal iyileştirme faktörünü (TEF) vermektedir (Re = 22.500’de TEF = 1.050). Buna karşılık, en yüksek TEF değeri PU TW1 konfigürasyonunda elde edilmiştir (Re = 5.000’de TEF = 1.473), bu yapı artan ısı transferi ile kabul edilebilir sürtünme kayıpları arasında en uygun dengeyi sağlamaktadır. Bu bulgular, güneş hava ısıtıcısı (SAH) sistemleri için tasarım odaklı çıkarımlar sunmakta; PU TW1 konfigürasyonunun enerji açısından en verimli düzenleme olduğunu, RW konfigürasyonunun ise minimum sürtünme kaybından ziyade maksimum ısı transferinin önceliklendirildiği uygulamalarda daha uygun olabileceğini göstermektedir.

Keywords

Isı transferi artırımı , Sayısal analiz , Güneş hava ısıtıcısı , Kanatçık tipli boyuna girdap üreticisi , GEKO türbülans modeli

References

• Dezan DJ, Rocha AD, Ferreira WG. Parametric sensitivity analysis and optimisation of a solar air heater with multiple rows of longitudinal vortex generators. Appl Energy [Internet]. 2020;263(January):114556. Available from: https://doi.org/10.1016/j.apenergy.2020.114556
• Sawhney JS, Maithani R, Chamoli S. Experimental investigation of heat transfer and friction factor characteristics of solar air heater using wavy delta winglets. Appl Therm Eng. 2017;117:740–51.
• Fiebig M. Vortices, generators and heat transfer. Chem Eng Res Des. 1998;76(2):108–23.
• Tang LH, Chu WX, Ahmed N, Zeng M. A new configuration of winglet longitudinal vortex generator to enhance heat transfer in a rectangular channel. Appl Therm Eng [Internet]. 2016;104:74–84. Available from: http://dx.doi.org/10.1016/j.applthermaleng.2016.05.056
• Skullong S, Promvonge P, Thianpong C, Jayranaiwachira N, Pimsarn M. Heat transfer augmentation in a solar air heater channel with combined winglets and wavy grooves on absorber plate. Appl Therm Eng [Internet]. 2017;122:268–84. Available from: http://dx.doi.org/10.1016/j.applthermaleng.2017.04.158
• Han JC, Park JS, Lei CK. Heat transfer enhancement in channels with turbulence promoters. J Eng Gas Turbines Power. 1985;107(3):628–35.
• Zhang G, Liu J, Sundén B, Xie G. Combined experimental and numerical studies on flow characteristic and heat transfer in ribbed channels with vortex generators of various types and arrangements. Int J Therm Sci. 2021;
• Promvonge P, Chompookham T, Kwankaomeng S, Thianpong C. Enhanced heat transfer in a triangular ribbed channel with longitudinal vortex generators. Energy Convers Manag [Internet]. 2010;51(6):1242–9. Available from: http://dx.doi.org/10.1016/j.enconman.2009.12.035
• Chompookham T, Thianpong C, Kwankaomeng S, Promvonge P. Heat transfer augmentation in a wedge-ribbed channel using winglet vortex generators. Int Commun Heat Mass Transf [Internet]. 2010;37(2):163–9. Available from: http://dx.doi.org/10.1016/j.icheatmasstransfer.2009.09.012
• Min C, Qi C, Kong X, Dong J. Experimental study of rectangular channel with modified rectangular longitudinal vortex generators. Int J Heat Mass Transf [Internet]. 2010;53(15–16):3023–9. Available from: http://dx.doi.org/10.1016/j.ijheatmasstransfer.2010.03.026
• Promvonge P, Khanoknaiyakarn C, Kwankaomeng S, Thianpong C. Thermal behavior in solar air heater channel fitted with combined rib and delta-winglet. Int Commun Heat Mass Transf [Internet]. 2011;38(6):749–56. Available from: http://dx.doi.org/10.1016/j.icheatmasstransfer.2011.03.014
• Colleoni A, Toutant A, Olalde G, Foucaut JM. Optimization of winglet vortex generators combined with riblets for wall/fluid heat exchange enhancement. Appl Therm Eng [Internet]. 2013;50(1):1092–100. Available from: http://dx.doi.org/10.1016/j.applthermaleng.2012.08.036
• Skullong S, Promvonge P. Experimental investigation on turbulent convection in solar air heater channel fitted with delta winglet vortex generator. Chinese J Chem Eng [Internet]. 2014;22(1):1–10. Available from: http://dx.doi.org/10.1016/S1004-9541(14)60030-6
• Chompookham T, Eiamsa-ard S, Promvonge P. Heat transfer enhancement of turbulent channel flow by baffles with rectangular, triangular and trapezoidal upper edges. J Eng Thermophys. 2015;24(3):296–304.
• Luo L, Wen F, Wang L, Sundén B, Wang S. Thermal enhancement by using grooves and ribs combined with delta-winglet vortex generator in a solar receiver heat exchanger. Appl Energy [Internet]. 2016;183:1317–32. Available from: http://dx.doi.org/10.1016/j.apenergy.2016.09.077
• Luo L, Wen F, Wang L, Sundén B, Wang S. On the solar receiver thermal enhancement by using the dimple combined with delta winglet vortex generator. Appl Therm Eng [Internet]. 2017;111:586–98. Available from: http://dx.doi.org/10.1016/j.applthermaleng.2016.09.096
• Chamoli S, Lu R, Xu D, Yu P. Thermal performance improvement of a solar air heater fitted with winglet vortex generators. Sol Energy [Internet]. 2018;159(December 2017):966–83. Available from: https://doi.org/10.1016/j.solener.2017.11.046
• Zhao Z, Luo L, Qiu D, Wang Z, Sundén B. On the solar air heater thermal enhancement and flow topology using differently shaped ribs combined with delta-winglet vortex generators. Energy. 2021;
• Fuentes H, Valencia A. Comparison of Turbulent Flow and Heat Transfer in a Rectangular Channel with Delta Wing and Winglet Type Longitudinal Vortex Generators. Int J Heat Technol. 2022;
• Cyriac B, Bhusnoor SS. Thermal and hydraulic characteristics of an air heater with modified delta flow obstructions. e-Prime - Adv Electr Eng Electron Energy. 2023;
• Demirağ HZ. Innovative approach for longitudinal vortex generator design: Impact on thermal performance. Therm Sci Eng Prog. 2024;49(January).
• Karkaba H, Dbouk T, Habchi C, Russeil S, Lemenand T, Bougeard D. Multiobjective optimization of Vortex Generators for heat transfer enhancement in turbulent flows. Int J Thermofluids. 2024;
• Wu G, Xu J, Wang H, Yin W. Optimized design of multiple vortex generator rows to enhance thermo-hydraulic performance in fully developed forced convection channel. Int Commun Heat Mass Transf [Internet]. 2024;157(June):107715. Available from: https://doi.org/10.1016/j.icheatmasstransfer.2024.107715
• İĞCİ AA. Enhancing heat transfer with a hybrid vortex generator combining delta wing and winglet designs: A numerical study using the GEKO turbulence model. Appl Therm Eng. 2025;258(April 2024).
• Versteeg H, Malalasekra W. An Introduction to Computational Fluid Dynamics: The Finite Volume Method-2nd Edition. Prentice Hall. 2007.
• ANSYS. Ansys Fluent Theory Guide Release 2021 R2 [Internet]. ANSYS, Inc. 2021. Available from: http://www.ansys.com
• Wilcox DC. Turbulence Modeling for CFD (Third Edition). DCW Ind. 2006;
• Menter FR, Lechner R, Matyushenko A. Best practice: generalized k-ω two-equation turbulence model in ANSYS CFD (GEKO). [Internet]. ANSYS Germany GmbH. 2019. Available from: http://refhub.elsevier.com/S0021-8502(21)00622-4/sref39
• Habchi C, Oneissi M, Russeil S, Bougeard D, Lemenand T. Comparison of eddy viscosity turbulence models and stereoscopic PIV measurements for a flow past rectangular-winglet pair vortex generator. Chem Eng Process - Process Intensif. 2021;
• Menter FR. Two-equation eddy-viscosity turbulence models for engineering applications. AIAA J. 1994;32(8):1598–605.
• Demirag HZ, Dogan M, Igci AA. The numerical analysis of novel type conic vortex generator and comparison with known VGs for heat transfer enhancement. Heat Mass Transf und Stoffuebertragung [Internet]. 2021;(0123456789). Available from: https://doi.org/10.1007/s00231-021-03117-7
• Oneissi M, Habchi C, Russeil S, Bougeard D, Lemenand T. Novel design of delta winglet pair vortex generator for heat transfer enhancement. Int J Therm Sci [Internet]. 2016;109:1–9. Available from: http://dx.doi.org/10.1016/j.ijthermalsci.2016.05.025
• Gesell H, Nandana V, Janoske U. Numerical study on the heat transfer performance and efficiency in a rectangular duct with new winglet shapes in turbulent flow. Therm Sci Eng Prog [Internet]. 2020;17:100490. Available from: https://doi.org/10.1016/j.tsep.2020.100490
• Tang XY, Zhu DS. Flow structure and heat transfer in a narrow rectangular channel with different discrete rib arrays. Chem Eng Process Process Intensif [Internet]. 2013;69:1–14. Available from: http://dx.doi.org/10.1016/j.cep.2013.01.005
• Yongsiri K, Eiamsa-Ard P, Wongcharee K, Eiamsa-Ard S. Augmented heat transfer in a turbulent channel flow with inclined detached-ribs. Case Stud Therm Eng [Internet]. 2014;3:1–10. Available from: http://dx.doi.org/10.1016/j.csite.2013.12.003
• Menter FR, Matyushenko A, Lechner R. Development of a Generalized K-ω Two-Equation Turbulence Model. Notes Numer Fluid Mech Multidiscip Des. 2020;142:101–9.
• Skullong S, Promthaisong P, Promvonge P, Thianpong C, Pimsarn M. Thermal performance in solar air heater with perforated-winglet-type vortex generator. Sol Energy. 2018;170(August 2017):1101–17.
• Incropera FP, DeWitt DP, Bergman TL, Lavine AS. Heat and Mass Transfer - Incropera 6e. Fundamentals of Heat and Mass Transfer. 2007.
• Fiebig M. Embedded vortices in internal flow: heat transfer and pressure loss enhancement. Int J Heat Fluid Flow. 1995;16(5):376–88.
• Tiggelbeck S, Mitra NK, Fiebig M. Comparison of wing-type vortex generators for heat transfer enhancement in channel flows. J Heat Transfer. 1994;116(4):880–5.
• Promvonge P, Changcharoen W, Kwankaomeng S, Thianpong C. Numerical heat transfer study of turbulent square-duct flow through inline V-shaped discrete ribs. Int Commun Heat Mass Transf [Internet]. 2011;38(10):1392–9. Available from: http://dx.doi.org/10.1016/j.icheatmasstransfer.2011.07.014