Cycle to Cycle Variations in S.I. Engines - The Effects of Fluid Flow and Gas Composition in the Vicinity of the Spark Plug on Early Combustion 962084
Simultaneous measurements of early flame speed and local measurements of the major parameters controlling the process are presented. The early flame growth rate was captured with heat release analysis of the cylinder pressure. The local concentration of fuel or residual gas were measured with laser induced fluorescence (LIF) on isooctane/3-pentanone or water. Local velocity measurements were performed with laser doppler velocimetry (LDV).
The results show a significant cycle to cycle correlation between early flame growth rate and several parameters. The experiments were arranged to suppress all but one important factor at a time. When the engine was run without fuel or residual gas fluctuations, the cycle to cycle variations of turbulence were able to explain 50 % of the flame growth rate fluctuations. With a significantly increased fluctuation of F/A, obtained with port fuelling, 65% of the growth rate fluctuation could be explained with local F/A measurements. With a homogeneous fuel/air-mixture but with a high concentration of residual, a correlation could be obtained between local residual concentration and combustion.
Citation: Johansson, B., "Cycle to Cycle Variations in S.I. Engines - The Effects of Fluid Flow and Gas Composition in the Vicinity of the Spark Plug on Early Combustion," SAE Technical Paper 962084, 1996, https://doi.org/10.4271/962084. Download Citation
1996 SAE International Fall Fuels and Lubricants Meeting and Exhibition
SAE 1996 Transactions - Journal of Engines-V105-3