A parametric investigation of methane jets in direct-injection compression-ignition conditions

Quancen Wan, Guanxiong Zhai, Cheng Wang, Anthony C.Y. Yuen, Paul R. Medwell, Sanghoon Kook, Guan Heng Yeoh, Qing Nian Chan

Research output: Journal article publicationJournal articleAcademic researchpeer-review

5 Citations (Scopus)


This work investigated the effects of ambient and injection conditions on the autoignition, flame evolution and combustion characteristics of the natural gas jets at direct-injection (DI) compression-ignition (CI) conditions. Methane (CH4, as a natural gas surrogate) was directly injected into an optically accessible constant-volume combustion chamber (CVCC). For the experiments, the ambient gas density within the CVCC was fixed at 24 kg m−3, but other ambient conditions were varied, including ambient gas temperature (1060–1200 K) and ambient oxygen concentration (10–21 vol.%). The effects of injection pressure (10–20 MPa reservoir pressure) were also assessed at a fixed ambient temperature and ambient oxygen conditions of 1200 K and 21 vol.%, respectively. High-speed schlieren imaging, heat release rate analysis and flame luminosity measurement were applied to the CH4 jet flames. The results show that the ignition delay decreases with increasing ambient temperature or ambient oxygen concentration but does not display an apparent trend with changing injection pressure. Optical images reveal that the CH4 jet combustion typically starts from a localised kernel before propagating downstream of the jet volume in most cases, other than the lower ambient oxygen concentration case. The optical results also reveal that after ignition, the CH4 jet flame recesses back towards the nozzle before stabilising at a lift-off distance. The jet becomes more lifted with a decreasing ambient temperature, a reducing ambient oxygen concentration, and an increasing reservoir pressure. The results also reveal that the heat release rate and flame luminosity profiles roughly correspond to the ignition and combustion characteristics of the CH4 jet flames.

Original languageEnglish
Article number126521
Publication statusPublished - 15 Feb 2023
Externally publishedYes


  • Constant-volume combustion chamber
  • Flame evolution
  • Flame stabilisation
  • Methane compression-ignition

ASJC Scopus subject areas

  • General Chemical Engineering
  • Fuel Technology
  • Energy Engineering and Power Technology
  • Organic Chemistry


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