DAİRESEL ÇARPAN BİR JETLE SOĞUTMANIN AKIŞ DİNAMİĞİ ETKİLERİNİN DENEYSEL OLARAK İNCELENMESİ

Öz

Bu çalışmada, dairesel çarpan jetin ısı transferi ve akış dinamiği üzerindeki etkileri deneysel olarak incelenmiştir. Çalışmada, jet akımı için çapı d =13.8 mm olan bir alüminyum boru kullanılarak, Reynolds sayısı 5000−25000 aralığında deneyler gerçekleştirilmiştir. Lüle ile çarpma yüzeyi arasındaki mesafe (h/d), farklı değerlerde değiştirilerek (2−10) jetin performansı değerlendirilmiştir. Yerel Nusselt sayıları (Nu), durma noktasındaki Nusselt sayısı (Nu0) ve ortalama Nusselt sayıları (Nuavg) detaylı şekilde analiz edilmiştir. Sonuçlar, h/d mesafesinin ve Reynolds sayısının ısı transferi performansı üzerinde önemli etkileri olduğunu göstermiştir. Artan Reynolds sayısı ve uygun h/d mesafeleri, durma noktasında daha yüksek ısı transferine olanak sağlamıştır. Bu bulgular, çarpan jetlerin enerji verimli soğutma uygulamalarındaki potansiyelini ortaya koymaktadır.

Anahtar Kelimeler

• Çarpan jetler
• Isı transferi
• Türbülans şiddeti

Experimental Investıgation Of Flow Dynamics Effects Of Cooling With A Circular Impınging Jet

Öz

This study experimentally investigates the effects of a circular impinging jet on heat transfer and flow dynamics. Using an aluminum nozzle with a diameter of d=13.8 mm, experiments were conducted within the Reynolds number range of 5000−25000. The nozzle-to-plate distance (h/d) was varied between h/d=2−10 to evaluate the jet's performance. Local Nusselt numbers (Nu), stagnation point Nusselt number (Nu0), and average Nusselt numbers (Nuavg) were analyzed in detail. The results demonstrated that both the nozzle-to-plate distance and Reynolds (Re) number significantly influence heat transfer performance. Increased Reynolds numbers and optimal h/d distances led to enhanced heat transfer at the stagnation point. These findings highlight the potential of impinging jets for energy-efficient cooling applications. The optimal nozzle-to-plate distance for maximum heat transfer was found to be h/d = 6, with a 30.5% increase in Nusselt number at Re = 25000. Additionally, turbulence intensity played a crucial role in heat transfer performance, particularly in the wall jet region, where it enhanced mixing and improved thermal efficiency.

Anahtar Kelimeler

• Impinging jets
• Heat Transfer
• Turbulent intensity

Etik Beyan

Ethical Statement The author declares that this document does not require ethics committee approval or any special permission. Conflict of Interest The author declares no conflict of interest.

Kaynakça

1. [1] K. Jambunathan, E. Lai, M. A. Moss, and B. L. Button, "A Review of Heat Transfer Data for Single Circular Jet Impingement," Int. J. Heat and Fluid Flow, vol. 13, no. 2, pp. 106–115, 1992.
2. [2] R. Gordon and J. C. Akfırat, "The Role of Turbulence in Determining the Heat Transfer Characteristics of Impinging Jets," Int. J. Heat and Mass Transfer, vol. 8, pp. 1261–1272, 1965.
3. [3] E. U. Schlunder and V. Gnielinski, "Heat and Mass Transfer between Surfaces and Impinging Jets," Chem. Ing. Tech., vol. 39, pp. 578–584, 1967.
4. [4] C. Kistak, A. Taskiran, and N. Celik, "Experimental Analysis of Transient and Steady-State Heat Transfer from an Impinging Jet to a Moving Plate," Heat and Mass Transfer, vol. 60, pp. 1713–1729, 2024.
5. [5] A.Taşkiran, C.Kıstak, S.Kapan, N.Çelik, and İ. Dağtekin, “Numerical Analysis of Dual Slot Pulsating Nanofluid Impinging Jets”, DUJE, vol. 15, no. 4, pp. 881–890, 2024.
6. [6] G. Bai, G. Gong, and F. Zhao, "Multiple Thermal and Moisture Removals from the Moving Plate Opposite to the Impinging Slot Jet," Appl. Therm. Eng., vol. 66, no. 1–2, pp. 252–265, 2014.
7. [7] N. Celik and H. Eren, "Heat transfer due to impinging co-axial jets and the jets’ fluid flow characteristics," Exp. Therm. Fluid Sci., vol. 33, pp. 715–727, 2009.
8. [8] K. Baghel et al., "Free Surface Planar Liquid Jet Impingement on a Moving Surface: Interfacial Flow and Heat Transfer Characteristics," J. Mech. Sci. Technol., vol. 36, no. 11, pp. 5537–5549, 2022.

9. [9] M. Rahimi and R. A. Soran, "Slot Jet Impingement Heat Transfer for the Cases of Moving Plate and Moving Nozzle," J. Brazilian Soc. Mech. Sci. Eng., vol. 38, pp. 2651–2659, 2016.
10. [10] J. Wang, X. Li, and S. A. Elmi, "Research on the Temperature and Thermal Stress of the Roll Quenching Process of Thin Plates," Metals, vol. 14, no. 1, p. 83, 2024.
11. [11] Sparrow, E.M., and Gregg, J.L., A Boundary Layer Treatment of Laminar Film Condensation, J. Heat Transfer, 81, 13, 1959
12. [12] Chen, M.M., An Analytical Study of Laminar Film Condensation Part I, J. Heat Transfer, 83, 48, 1961
13. [13] Çelik, N., Optimum Lüle Tipinin Çarpan Jet Üzerindeki Etkilerinin İncelenmesi, Doktora Tezi, Fırat Üniv. Fen. Bil. Ens. Elazığ, 2006
14. [14] Churchill, S.W. and Chu, H.H.S. (1975) Correlating Equations for Laminar and Turbulent Free Convection from a Vertical Plate. International Journal of Heat and Mass Transfer, 18, 1323-1329.
15. [15] Kline, S.J., McClintock, F.A., Describing uncertainties in single-sample experiments, Mechanical Engineering 75, 3–8, 1953
16. [16] Sfeir, A.A., “The Velocity and Temperature Fields of Rectangular Jet”, Int. J. Heat and Mass Transfer, 19, 1289-1297, 1976.
17. [17] Yevdjevıch, V.M., “Diffusion of Slot Jets with Finite Length-Width Ratio”, Hydraulic Paper, Colarado State Univ. 2, 1-40, 1966.
18. [18] Sforza, P.M., Steiger, M.H., & Trentacoste, N., “Studies on Three Dimensional Viscous Jets”, AIAA J. 4, 800-806, 1966.
19. [19] Gauntner, J.W., Livingood, J.N.B., and Hrycak, P., “Survey of Literature on Flow Characteristics of Single Turbulent Jet Impinging on a Flat Plate”, NASA TN D-5652 NTIS N70-18963, 1970.
20. [20] Blevins, R.D., Applied Fluid Dynamics Handbook, Florida, 1992.
21. [21] Schlichting, H., Boundary Layer Theory, McGraw Hill Co., New York, 1968.
22. [22] Popiel, C.O., and Trass, O., “The Effect of Ordered Structure of Turbulence on Momentum, Heat and Mass Transfer of Impinging Round Jets, Proc.7th Int. Heat Transfer Conf., Munchen, Germany, September 6-10, 6, 141-146, 1982.
23. [23] Popiel, C.O., and Trass, O., “Visualization of a Free and Impinging Round Jet”, Exp. Thermal Fluid Science, 4, 253-264, 1991.
24. [24] Lee, D.H., Chung, Y.S. and Kim, D.S., “Turbulent Flow and Heat Transfer Measurements on a curved surface with a Fully Developed Round Impinging Jet”, Int. J. Heat and Fluid Flow, 18, 160-169, 1997.
25. [25] Can, O., “Elektronik Devrelerin Soğutulması ve Jet Püskürtmeli Soğutma Sistemlerinin Analizi” Yüksek Lisans Tezi, İTÜ Fen Bilimleri Enstitüsü, İstanbul, 1997.
26. [26] Tani, I., and Komatsu, Y., “Impingement of a Round Jet on a Flat Surface”, Proc. of the Eleventh International Congress of Applied Mechanics, (Editor H. Gortler), Springer-Verlag, New York, 672-676, 1966.
27. [27] Girald, F.,Chia C.J., and Trass, O., “ Characterization of the Impingement Region in an Axisymmetric Turbulent Jet”, Ind. Eng. Chem. Fundam. 16, 21-28, 1977.