Influences of excess air coefficient on combustion and emission performance of diesel pilot ignition natural gas engine by coupling computational fluid dynamics with reduced chemical kinetic model

•Chemical mechanism was introduced to study λ ’s effect on natural gas-diesel engine.•Each combustion stage of natural gas-diesel engine was quantitatively analyzed.•The higher λ leads the heat release rate to shoot up earlier.•The 10–50% and 50–90% combustion duration become longer as λ increases f...

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