High-speed ultraviolet chemiluminescence imaging of late combustion in diesel spray flame

For modern diesel engines employing relatively small injector nozzle holes, reduction of late combustion in high load operation is an attractive potential strategy to shorten the combustion period and thus thermal efficiency. However, the governing mechanism of the late combustion has not intensively been studied. This study aims to experimentally investigate where in the diesel spray flame the late combustion heat release is occurring and what governs the phenomenon. As a practical and qualitative marker of local heat release location and existence, which is applicable not only to idealized vessel experiments but also to future production engine experiments, ultraviolet emission from diesel spray flame during the late combustion was examined. First, the ultraviolet emission spectra of diesel spray flame during the late combustion were measured and found to mainly consist of OH* chemiluminescence with some background due to broadband CO2* chemiluminescence and soot luminosity ultraviolet components. Second, simultaneous high-speed imaging of 310?nm ultraviolet emission and visible soot luminosity from flame were performed to distinguish the OH* chemiluminescence from the soot luminosity. Third, simultaneous high-speed imaging of 310?nm ultraviolet emission, visible soot luminosity, and 266?nm ultraviolet absorption in diesel spray flame were performed, showing similar spatial and temporal distributions of heat release locations and combustible mixtures during the late combustion. The observation results suggest that the late combustion heat release occurs in the mixtures losing momentum and accumulated at the spray tip region.

Language

  • English

Media Info

  • Media Type: Web
  • Features: References;
  • Pagination: pp 93-104
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 01713958
  • Record Type: Publication
  • Files: TRIS
  • Created Date: May 24 2019 4:49PM