The effect of fuel mixture strength and ignition timing on flame propagation in the spark ignition engine was investigated, and the significance of intake-generated turbulence was assessed using a vortex generator (several delta-shaped wings joined at their apexes and positioned in the inlet port). The test vehicle was a single-cylinder, four-stroke, variable compression ratio Renault with a spark ignition engine. The engine was run on gasoline at four speeds (1000, 1500, 2000, and 2500 rpm), and tests were conducted to obtain the optimum spark timing over a range of mixture strengths. Engine speed, throttle angle and ignition timing, and percentage of flame arrivals across the combustion chamber were measured for three conditions: no vortex generator (datum); 50% blockage ratio vortex generator; and 85% blockage ratio vortex generator. Results showed that flame speed and lean extinction limit may be increased by fitting a vortex generator in the engine intake. The vortex generator should be of variable geometry and replace the conventional throttle. The main instrument on the engine consists of a flame logger which accepts amplified signals from ionization probes set in the engine combustion chamber. The logger is gated to count flames which travel across the combustion chamber during a set crank angle period. Information from this instrumentation is presented in the form of graphs describing the effect of vortex generator blockage ratio, mixture strength, engine speed and load, and spark timing on the percentage number of flames which cross the chamber and on the apparent flame speed. It is demonstrated that the beneficial effect of a vortex generator is more pronounced in the lean mixture region and that measured flame speed is increased using the generator.

  • Availability:
  • Supplemental Notes:
    • Presented at SAE International Fuels and Lubricants Meeting, Toronto, 13-16 November 1978.
  • Corporate Authors:

    Society of Automotive Engineers (SAE)

    400 Commonwealth Drive
    Warrendale, PA  United States  15096
  • Authors:
    • LUCAS, G G
    • Brunt, M
    • Petrovic, S
  • Publication Date: 1978

Media Info

Subject/Index Terms

Filing Info

  • Accession Number: 00399220
  • Record Type: Publication
  • Source Agency: National Highway Traffic Safety Administration
  • Report/Paper Numbers: SAE 780964, HS-025 906U
  • Contract Numbers: S-R-C-B/RG/5956.0
  • Files: HSL, USDOT
  • Created Date: Oct 31 1985 12:00AM