Bir Dizel Motorunda Soğuk Başlatma Koşullarında Silindir İçi Girdap Hareketinin Sayısal Araştırması

Öz

The performance and efficiency of internal combustion engines, particularly diesel engines, are closely tied to the quality of air-fuel mixing and combustion processes. One of the critical factors influencing these processes is the in-cylinder airflow, specifically the swirl motion, which is the rotational movement of air around the cylinder axis. This swirl plays a pivotal role in enhancing the turbulence required for efficient fuel-air mixing, accelerating flame development, and improving overall combustion. This study shows a numerical analysis of the swirl movement within the cylinder of a diesel engine under cold starting conditions. Using computational fluid dynamics (CFD) analysis, the research evaluates the effects of various valve opening configurations on swirl intensity. The results indicate that increasing valve openings generally enhances swirl motion, improving combustion efficiency by promoting better air-fuel mixing. However, excessive swirl can negatively impact performance due to increased heat transfer and potential flame propagation issues. The study also assesses the impact of turbulence models and mesh density on the accuracy of the results, with the k-ε model providing predictions closest to experimental data. These findings contribute to optimizing engine design for improved combustion characteristics and reduced emissions.

Anahtar Kelimeler

• Cold flow
• Swirl motion
• Computational fluid dynamics

Numerical investigation of in-cylinder swirl motion under cold start conditions in a diesel engine

Öz

The performance and efficiency of internal combustion engines, particularly diesel engines, are closely tied to the quality of air-fuel mixing and combustion processes. One of the critical factors influencing these processes is the in-cylinder airflow, specifically the swirl motion, which is the rotational movement of air around the cylinder axis. This swirl plays a pivotal role in enhancing the turbulence required for efficient fuel-air mixing, accelerating flame development, and improving overall combustion. This study shows a numerical analysis of the swirl movement within the cylinder of a diesel engine under cold starting conditions. Using computational fluid dynamics (CFD) analysis, the research evaluates the effects of various valve opening configurations on swirl intensity. The results indicate that increasing valve openings generally enhances swirl motion, improving combustion efficiency by promoting better air-fuel mixing. However, excessive swirl can negatively impact performance due to increased heat transfer and potential flame propagation issues. The study also assesses the impact of turbulence models and mesh density on the accuracy of the results, with the k-ε model providing predictions closest to experimental data. These findings contribute to optimizing engine design for improved combustion characteristics and reduced emissions.

Anahtar Kelimeler

• Cold flow
• Swirl motion
• Computational fluid dynamics

Kaynakça

1. [1] Taştan M, Mızrak KC. Investigation of propane combustion at different equivalent ratios in a premixed model burner. International Journal of Energy Studies 2023; 8(4): 731-746.
2. [2] Aktas F. Three-Dimensional Computational Fluid Dynamics Simulation and Mesh Size Effect of the Conversion of a Heavy-Duty Diesel Engine to Spark-Ignition Natural Gas Engine. J. Eng. Gas Turbines Power 2022; 144(6): 061004.
3. [3] Aktaş F, Yücel N. Dizel bir motorun reaktivite kontrollü sıkıştırma ateşlemeli bir motora dönüşümünde farklı oranlarda propan kullanımının ve yanma başlangıç zamanının performans, emisyon ve silindir içi yanma karakteristiklerine olan etkilerinin incelenmesi. Gazi Üniversitesi Mühendislik Mimarlık Fakültesi Dergisi 2023; 39(2): 785-796.
4. [4] Aktas F. Numerical investigation of the effect of swirl number on performance, combustion, and emissions characteristics in a converted heavy-duty natural gas engine. Progress in Computational Fluid Dynamics, an International Journal 2024; 24(3): 162-173.
5. [5] Polat S, Yücesu HS, Kannan K, Uyumaz A, et al. Experimental comparison of different injection timings in an HCCI engine fueled with n-heptane. International Journal of Automotive Science And Technology 2017; 1(1): 1-6.
6. [6] Temizer İ, Cihan Ö, Öncüoğlu Ö. Numerical investigation of different combustion chamber on flow, combustion characteristics and exhaust emissions. European Mechanical Science 2023; 7(1): 7-15.
7. [7] Wang Y, Zhang Y, Li Q. An analytic study of applying Miller cycle to reduce NOx emission from petrol engine. Applied Thermal Engineering 2007; 27(11-12): 1779-1789.
8. [8] Pehlivan EF, Altın İ. A full-scale CFD model of scavenge air inlet temperature on two-stroke marine diesel engine combustion and exhaust emission characteristics. Int J Energy Studies 2024; 9(3): 493-517.

9. [9] Kethüdaoğlu G, Aktaş F, Karaaslan S, Polat S, Dinler N. Investigation of conversion of a diesel engine to homogeneous charge compression ignition engine using n-heptane: A zero-dimensional modeling. Int J Energy Studies 2023; 8(3): 535-556.
10. [10] Heywood JB. Internal combustion engine fundamentals. McGraw-Hill Education 2018.
11. [11] Arcoumanis C, Bicen AF, Vafidis C, Whitelaw JH. Three-dimensional flow field in four-stroke model engines. SAE Technical Paper 1984; 841360.
12. [12] Arcoumanis C, Bicen AF, Whitelaw JH. Squish and swirl-squish interaction in motored model engines. Journal of Fluids Engineering 1983; 105(1): 105-112.
13. [13] Demirkesen C, Colak U, Savci IH, Zeren HB. Experimental and numerical investigation of air flow motion in cylinder of heavy-duty diesel engines. Journal of Applied Fluid Mechanics 2020; 13(2): 537-547.
14. [14] Huang RF, Lin KH, Yeh CN, Lan J. In-cylinder tumble flows and performance of a motorcycle engine with circular and elliptic intake ports. Experiments in Fluids 2009; 46(1): 165-179.
15. [15] Kaplan M, Özbey M, Özcan H. Numerical investigation of the effects of intake port geometry on in-cylinder motion and combustion in diesel engines. International Journal of Engineering Science 2018; 7: 16-26.
16. [16] Taghavifar H, Khalilarya S, Jafarmadar S. Engine structure modifications effect on the flow behavior, combustion, and performance characteristics of DI diesel engine. Energy Conversion and Management 2014; 85: 20-32.
17. [17] Payri F, Benajes J, Margot X, Gil A. CFD modeling of the in-cylinder flow in direct-injection diesel engines. Computers & Fluids 2004; 33(8): 995-1021.
18. [18] Choi GH, Kim JH, Lee HS, Park SB. A numerical study of the effects of swirl chamber passage hole geometry on the flow characteristics of a swirl chamber type diesel engine. Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 2006; 220(4): 459-470.
19. [19] Jemni MA, Kantchev G, Abid MS. Influence of intake manifold design on in-cylinder flow and engine performances in a bus diesel engine converted to LPG gas fuelled, using CFD analyses and experimental investigations. Energy 2011; 36(5): 2701-2715.
20. [20] Shafie NAM, Said MFM. Cold flow analysis on internal combustion engine with different piston bowl configurations. Journal of Engineering Science and Technology 2017; 12(4): 1048-1066.
21. [21] Wahono B, Setiawan A, Lim O. Experimental study and numerical simulation on in-cylinder flow of small motorcycle engine. Applied Energy 2019; 255: 113863.
22. [22] Topkaya H, Işık MZ, Çelebi Y, Aydın H. Numerical analysis of various combustion chamber bowl geometries on combustion, performance, and emissions parameters in a diesel engine. International Journal of Automotive Engineering and Technologies 2024; 13(2): 63-72.
23. [23] Aktas F. Bir dizel motorda çift yakıt olarak propan-dizel kullanımının yanma rejimine, motor performansına ve emisyon değerlerine olan etkilerinin sayısal olarak incelenmesi. PhD thesis, Graduate School of Natural and Applied Sciences, Gazi University 2021.
24. [24] Crnojevic C, Decool F, Florent P. Swirl measurements in a motor cylinder. Experiments in Fluids 1999; 26(6): 542-548.
25. [25] FEV Magazine. Customized test bench flow investigation. Retrieved from Online Web Site: https://magazine.fev.com/en/fev-customized-test-bench-flow-investigation/
26. [26] Ansys, Inc. ANSYS CFX-solver theory guide release 2020-R1. ANSYS, Inc. 2020.
27. [27] Antila E, Imperato M, Kaario O, Larmi M. Effect of intake channel design to cylinder charge and initial swirl. SAE Technical Paper 2010; 2010-01-0624.
28. [28] Güney H. Tier IV emisyon seviyesine sahip bir dizel motorun hesaplamalı akışkanlar dinamiği ile akış ve yanma analizi. Master's thesis, TOBB University of Economics and Technology 2014.
29. [29] Ramajo DE, Nigro NM. In-cylinder flow computational fluid dynamics analysis of a four-valve spark ignition engine: Comparison between steady and dynamic tests. Journal of Engineering for Gas Turbines and Power 2010; 132(5): 1-10.