Prediction of the mean turbulence intensity with a thermodynamic model for CNG and gasoline fuels

Hüseyin Emre Doğan*, Abdurrahman Demirci, Osman Akın Kutlar, Hikmet Arslan, Ömer Cihan

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Combustion is the main parameter that affects efficiency and exhaust gas emissions in internal combustion engines. In this study, the burning speed of gasoline and CNG were investigated quantitatively by calculating the mean value of turbulent consumption speed instead of qualitatively as is usually done. A three-zone quasi-dimensional thermodynamic model based on the measured cylinder pressure was created to calculate the mean value of turbulent consumption speed and turbulence intensity. The mass flow rate of air was kept constant in all experiments as much as possible, and the spark advance was kept constant at each relative air/fuel ratio. Thus, the effect of fuel and combustion chamber design on the consumption speed and turbulence intensity was directly determined. MR shape reached the highest consumption speed and turbulence intensity in all conditions. In the flat geometry, without any bowl, speed continuously decreased differently from the other designs. Natural gas burned clearly faster in the ultra-lean mixture. The increase in turbulence intensity has different effects on CNG and gasoline. The highest value of the mean turbulence intensity was calculated as approximately 3.4 m/s in the MR design. In the ultra-lean mixture, although the mass flow rate of air was constant, the mean value of the turbulence intensity changed in the same combustion chamber. Therefore, it has been determined that the combustion process affects the turbulence intensity. Using the quasi-dimensional thermodynamic model, mean values of the turbulent burning speeds and turbulence intensity might be calculated without having any optical observation and CFD analysis.

Original languageEnglish
Article number128532
Publication statusPublished - 15 Sept 2023

Bibliographical note

Publisher Copyright:
© 2023 Elsevier Ltd


The authors wish to thank TUBITAK (Scientific and Technological Research Council of Turkey) for their support of the scientific research (Project No. 218M232). Finally, the authors also are grateful to Prof. Dr. Rafig Mehdiyev for his contribution in selecting and design of combustion chamber geometries.

FundersFunder number
Türkiye Bilimsel ve Teknolojik Araştırma Kurumu218M232


    • CNG
    • Combustion chamber design
    • Global consumption speed
    • Quasi-dimensional model
    • Turbulence intensity
    • Wrinkling factor


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