Estimates of the air-fuel ratio at the time of ignition in a pre-chamber using a narrow throat geometry
Artikel i vetenskaplig tidskrift, 2023

The benefits of pre-chamber combustion (PCC), such as improved engine efficiency and reduced NOx emissions, are primarily observed when operating at lean conditions with an active pre-chamber, where auxiliary fuel is supplied directly to the pre-chamber. Estimating the pre-chamber excess air ratio (λ) is important in the active pre-chamber concept to gain insights into the pre-chamber combustion phenomenon. Experimental investigations were performed using a narrow-throat pre-chamber at global-λ 1.6, 1.8, and 2.0. The fraction of fuel energy injected in the pre-chamber over the total fuel energy was fixed at 3%, 7%, and 13% for each global-λ. The mixture formation process inside the pre-chamber is first simulated using the 1-D simulation software GT-Power to analyze the pre-chamber λ at the ignition timing. However, the 1-D results were unable to reproduce the experimental observations on the pre-chamber pressure buildup accurately. Upon simulating the same conditions using the 3-D CFD software CONVERGE, the pre-chamber λ estimated from the CFD model is well-correlated to the experimental data. The CFD results indicate that the amount of fuel trapped in the pre-chamber at the inlet valve closing timing is over-predicted by the 1-D simulations. A correlation between the injected and the trapped fuel in the pre-chamber is proposed by theoretical scavenging models and applied to the 1-D simulation results to improve pre-chamber λ prediction accuracy.


computational fluid dynamics

fuel stratification

lean combustion


Ponnya Hlaing

King Abdullah University of Science and Technology (KAUST)

Mickael Silva

King Abdullah University of Science and Technology (KAUST)

Manuel Echeverri Marquez

King Abdullah University of Science and Technology (KAUST)

Emre Cenker

Saudi Arabian Oil Company (Saudi Aramco)

Moez Ben Houidi

King Abdullah University of Science and Technology (KAUST)

Hong G. Im

King Abdullah University of Science and Technology (KAUST)

James Turner

King Abdullah University of Science and Technology (KAUST)

Bengt Johansson

Chalmers, Mekanik och maritima vetenskaper, Förbränning och framdrivningssystem

Kompetenscentrum i Förbränningsmotorteknik (CERC)

International Journal of Engine Research

1468-0874 (ISSN)

Vol. 24 2 622-638


Annan maskinteknik


Strömningsmekanik och akustik



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