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MODES AND MEASURES OF CYCLIC COMBUSTION VARIABILITY

A single-cylinder engine with a transparent piston crown was tested with three intake geometries which produced different levels of swirl, and with two spark locations. A heat-release analysis was performed on the accumulated pressure-time data. Using this data base, relationships of maximum cycle pressure and its location in the cycle to the placement of the burn in the cycle are developed for different burning rates as a means of diagnosing sources of combustion variability. Among the significant observations were that combustion variability for operation away from the lean limit or incipient misfire is not strongly dependent on flow conditions at the spark plug and early flame behavior, but more dependent on the cyclic repeatability of the overall cylinder flow pattern. In the region of incipient misfire the early flame process becomes a significant source for variability. The onset of significant variability in IMEP corresponds to a condition where a collection of cycles shows the production of an increasing number of abnormally late burns as the spark is advanced. Additional spark advance results in the occurrence of misfire at approximately the frequency of the late-burn occurrence.

  • Availability:
  • Supplemental Notes:
    • International Congress and Exposition, Detroit, Michigan, February 28-March 4, 1983.
  • Corporate Authors:

    Society of Automotive Engineers (SAE)

    400 Commonwealth Drive
    Warrendale, PA  United States  15096
  • Authors:
    • Matekunas, F A
  • Publication Date: 1983

Media Info

  • Features: Appendices; Figures; References; Tables;
  • Pagination: 18 p.
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00379696
  • Record Type: Publication
  • Source Agency: National Highway Traffic Safety Administration
  • Report/Paper Numbers: SAE 830337, HS-035 018
  • Files: HSL, USDOT
  • Created Date: Nov 30 1983 12:00AM