TÜRBÜLANSLI YANMA İÇİN DÖNDÜRÜCÜNÜN PARAMETRİK ÇALIŞMASI

Öz

Bu çalışmada döndürücüye ait kanat sayısı, kanat sarım açısı ve kanat uzunluğu ile yakıt giriş çapının yanma odasındaki türbülanslı akış yapısı, yanma verimi ve emisyon değerleri üzerine etkisi araştırılmıştır. Referans alınan döndürücü kanat sayısı (n), kanat uzunluğu (L), kanat sarım açısı (θ) ve yakıt giriş çapı (D2) sırası ile 10, 40 mm, 45°, 19.5 mm’dir. Kanat sayısı (6,8,10,12,14), kanat uzunluğu (0.5L, L, 1.5L, 2L), kanat sarım açısı (30°, 45°, 60°, 75°, 90°, 120°) ve yakıt giriş çapı için (0.5 D2, D2, 1.5 D2, 2 D2) parametrik değerler kullanılarak yeni modeller oluşturulmuştur. Sayısal çalışmalar ANSYS/Fluent 17.2 ticari yazılımı ile gerçekleştirilmiş ve referans alınan deneysel çalışmaya uygun olarak önceden karışmamış yanma modeli tanımlanmıştır. Sayısal yöntem, elde edilen verilerin deneysel veriler ile karşılaştırılması ile doğrulanmıştır. Analizler sonucu olarak kanat sarım açısının alev şekli, kanat uzunluğunun ise alevin simetrik yapısı üzerine önemli etkisinin olduğu bulunmuştur. M04510403900 (θ=45°, n=10, L=40 mm, D2=39.00 mm) modelinde en yüksek ısıl verim elde edilmiş ve % 79.3 olan referans döndürücünün ısıl verimi bu model ile % 93.8’e yükselmiştir. Yanma odası seyreltme delikleri öncesinde CO kütle fraksiyonu değerinin referans döndürücü modelinde 0.002 olduğu ve M04510400975 (θ=45°, n=10, L=40 mm, D2=9.75 mm) modelinde bu değerin 0.018’e yükseldiği tespit edilmiştir.

Anahtar Kelimeler

• Döndürücü tasarımı
• Hesaplamalı Akışkanlar Dinamiği
• Kanat sayısı
• Kanat uzunluğu
• Önceden karışmamış yanma modeli
• Sarım açısı
• Yakıt giriş çapı

A PARAMETRIC STUDY ON THE SWIRLER FOR TURBULENT COMBUSTION

Öz

In this study, the effects of the number of swirler blades, swirler blade wrape angle, swirler blade length and the fuel inlet diameter on the turbulent flow structure, combustion efficiency and emission in a combustion chamber have been investigated. The number of blades (n), the blade length (L), the blade wrape angle (θ) and the fuel inlet diameter (D2) of the swirler blades were taken as 10, 40 mm, 45° and 19.5 mm, respectively. New models were created using the parameters of the blade number (6,8,10,12,14), the blade length (0.5L, L, 1.5L, 2L), the blade wrape angle (30°, 45°, 60°, 75°, 90°, 120°) and the fuel inlet diameter (0.5 D2, D2, 1.5 D2, 2 D2). Numerical analysis were performed using ANSYS/Fluent 17.2 commercial software and non-premixed combustion model was defined according to the referenced experimental study. Numerical method was validated with the comparison of numerical and experimental data. It is concluded that the wrape angle has a significant effect on the flame shape and the blade length on the symmetrical structure of the flame. The highest thermal efficiency was obtained for the model M04510403900 (θ =45°, n=10, L =40 mm, D2=39.00 mm) and the thermal efficiency of the referenced swirler geometry of 79.3% were increased to 93.8% with this model. It has been seen that CO mass fraction value upstream of the dilution holes was 0.002 for referenced swirler model and this value increased to 0.018 for the model M04510400975 (θ=45°, n=10, L=40 mm, D2=9.75 mm).

Anahtar Kelimeler

• Swirler design
• Computational Fluid Dynamics
• Blade number
• Blade length
• Non-premixed combustion
• Wrap angle
• Fuel inlet diameter

Kaynakça

1. Abubakar Z., Shakeel M. R. and Mokheimer E. M. A., 2018, Experimental and Numerical Analysis of Non-Premixed Oxy-Combustion of Hydrogen-Enriched Propane in a Swirl Stabilized Combustor, Energy, 165, 1401-1414.
2. Eldrainy Y.A., Saqr K. M., Aly H.S. and Mohd Jaafar M. N., 2009, CFD insight of the flow dynamics in a novel swirler for gas turbine combustors, International Communications in Heat and Mass Transfer, 36, 936-941.
3. Hoda A., Rahman T. M. R., Asrar W. and Khan S. A., 2021, A Comparative Study of Natural Gas and Biogas Combustion in A Swirling Flow Gas Turbine Combustor, Combustion Science and Technology, https://doi.org/10.1080/00102202.2021.1882441
4. İlbaş M., Karyeyen S. and Yilmaz İ., 2016, Effect of swirl number on combustion characteristics of hydrogen-containing fuels in a combustor, International Journal of Hydrogen Energy, 41, 7185-7191.
5. Jones W. P. and Whitelaw J. H., 1982, Calculation Methods for Reacting Turbulent Flows: A Review, Combustion and Flame. 48, 1-26.
6. Jeong Y. K., Jeon C. H. and Chang Y. J., 2004, Effects of a Swirling and Recirculating Flow on the Combustion Characteristics in Non-Premixed Flat Flames, KSME International Journal, 18, 499-512.
7. Kwark J. H., Jeong Y. K., Jeon C. H. and Chang Y. J., 2004, Effect of Swirl Intensity on the Flow and Combustion of a Turbulent Non-Premixed Flat Flame, Flow, Turbulent and Combustion, 73, 231-257.
8. Launder B. E. and Spalding D. B., 1974, The Numerical Computation of Turbulent Flow, Computer Methods in Applied Mechanics and Engineering, 3, 269-289.

9. Lefebvre A.H. and Ballal D. R., 2010, Gas Turbine Combustion Alternative Fuels and Emissions, 140-146.
10. Mardani A., Tabejamaat S. and Hassanpour S., 2013, Numerical Study of CO and CO2 formation in CH4/H2 blended flame under MILD condition, Combustion and Flame, 160, 1636-1649.
11. Mattingly D. J., Heiser W. H. and Pratt D. T., 2002, Aircraft Engine Design, 330-339
12. Midgley K., Spencer A. and McGuirk J. J., 2005, Unsteady flow structures in radial swirler fed fuel injectors, Journal of Engineering for Gas Turbines and Power, 127, 755-764.
13. Ohtake K., 1993, Advanced Combustion Science, 1-7.
14. Patel V. and Shah R., 2019, Effect of Swirl and Number of Swirler Vanes on Combustion Characteristics of Methane Inverse Diffusion Flame, Journal of Mechanical Science and Technology, 33, 1947-1958.
15. Poinsot T. and Veynante D., 2005, Theoretical and Numerical Combustion, 313-325.
16. Pourhoseini H.S. and Asadi R., 2017, An Experimental Study of Optimum Angle of Air Swirler Vanes in Liquid Fuel Burners, Journal of Energy Resources Technology, DOI: 10.1115/1.4035023
17. Prakash R.S., Santhosh K.S. and Sadanandan R., 2020, Flame Characteristics and Pollutant Emissions of a Non-premixed Swirl Burner with Annular Swirling Fuel Injection, Recent Asian Search on Thermal and Fluid Sciences, DOI: 10.1007/978-981-15-1892-8_42.
18. Rajabi V. and Amani E., 2018, A Computational Study of Swirl Number Effects on Entropy Generation in Gas Turbine Combustors, Heat Transfer Engineering, DOI:10.1080/01457632.2018.1429056.
19. Sayyar A. and Davani A., 2021, Numerical optimization of flame stability in a swirl combustion chamber with helical tapes, Thermal Science and Engineering Progress, https://doi.org/10.1016/j.tsep.2020.100815
20. Serag-Eldin M. A., and Spaldin D. B., 1979, Computations of Three-Dimensional Gas-Turbine Combustion Chamber Flows, The American Society of Mechanical Engineers, 101, 326-336.
21. Shah R. D., 2015, Thermal and Emission Characteristics of a Can Combustor, Heat Mass Transfer, 52, 499-509.
22. Shahin I., Elsemary I. M. M, Abdel-Rehim A. A., Attia A. A. A. and Elnagar K. H., 2016, Optimization of stepped conical swirler with multiple jets for pre-mixed turbulent swirl flames, Applied Thermal Engineering, 102, 359-374.
23. Tret’yakov V. V., 2007, Calculation of fuel distribution in the combustion chamber front device equipped with a three-stage swirler, Russian Aeronautics, 50, 395-401.
24. Wang X., Lin Y., Zhang C. and Tian X., 2015, Effects of Swirl Cup’s Secondary Swirler on Flow Field and Ignition Performance, Journal of Thermal Science, 24, 488-495.
25. Williams F. A., Combustion Theory, 1985, The Benjamin Cummings, 375-382.
26. Yılmaz I.., Effect of Swirl Number on Combustion Charateristics in a Natural Gas Diffusion Flame, 2013, Journal of Energy Resources Technology, https://doi.org/10.1115/1.4024222
27. Yihua X., Rui J., Humberto M. and Haijun S., 2019, Effect of Tangential Swirl Air Inlet Angle on the Combustion Efficiency of a Hybrid Powder-Solid Ramjet, Acta Astronautica, 159, 87-95.
28. Zhou L.X., 2018, Comparison of studies on flow and flame structures in different swirl combustors, Aerospace Science and Technology, 80, 29-37