Influence of Pre-Chamber Structure on Jet and
Combustion Characteristics of Methanol Engine

Vehicle Engine ›› 2026, Vol. 0 ›› Issue (1) : 1-8.

Influence of Pre-Chamber Structure on Jet and Combustion Characteristics of Methanol Engine

LAI Kaichang^1,2，CHEN Hong²，DU Jiakun²，MA Yibo¹，WANG Liming¹，XIE Fangxi^1,2

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Abstract

Based on an active pre-chamber methanol jet ignition engine, a simulation platform was developed using CONVERGE software.Building upon the original pre-chamber geometry, the cross-sectional area of throat was modified along the axial direction to create three distinct configurations: a gradually constricting throat (P1), a conventional uniform throat (P2) and a gradually expanding throat (P3). The flame jet dynamics and engine combustion characteristics were systematically studied across these different throat geometries. The results show that the gradually expanding throat promotes more uniform reactant distribution within the pre-chambe due to its lower velocity gradient, thereby enchancing mixture homogeneity-although all three configurations exhibit a pronounced concentration gradient at the throat region. In contrast, the gradually constricting throat design imposes stronger combustion confinement and produces a more focused jet with a higher momentum discharge, resulting from the largest pressure difference between the pre-chamber and the main combustion chamber. Consequently, this configuration acheieves faster flame propagation and greater jet kinetic energy, which further enhances turbulent mixing and combustion efficiently in the main combustion chamber. As a result, the peak cylinder pressure increases by 0.129 MPa and 0.912 MPa compared to the P2 and P3 designs respectively, while the peak heat release rate significantly increases and the combustion phase advances.

Key words

methanol engine

/ active pre-chamber / jet ignition / combustion characteristic

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LAI Kaichang, CHEN Hong, DU Jiakun, MA Yibo, WANG Liming, XIE Fangxi. Influence of Pre-Chamber Structure on Jet and Combustion Characteristics of Methanol Engine[J]. Vehicle Engine. 2026, 0(1): 1-8