The knock study of methanol fuel based on multi-dimensional simulation analysis

Methanol is an alternative fuel, and considered to be one of the most favorable fuels for engines. In this study, knocking combustion in a developed ORCEM (optical rapid compression and expansion machine) is studied based on the multi-dimensional simulation analysis. The LES (large-eddy simulation) models coupled with methanol chemical reaction kinetics (contains 21-species and 84-elementary reactions) is adopted to study knocking combustion. The results showed that the end-gas auto-ignition first occurred in the position near the chamber wall because of the higher temperature and pressure. The H₂O₂ species could be a good flame front indicator. OH radicals played the major role, and the HCO radicals almost could be ignored during knocking combustion. The HCO radicals generated little, so its concentration during knocking combustion almost may be ignored. The mean reaction intensity results of CH₂O, OH, H₂O₂, and CO were higher than others during knocking combustion. Finally, this paper put forward some new suggestions on the weakness in the knocking combustion researches of methanol fuel. - Highlights: • Knocking combustion of methanol was studied in a developed ORCEM. • The LES coupled with detailed chemical kinetics was adopted to simulation study. • The end-gas auto-ignition first occurred in the place near the chamber wall. • OH radical was the predominant species during knocking combustion. • The H₂O₂ species could be a good flame front indicator.