This content is not included in
your SAE MOBILUS subscription, or you are not logged in.
An Experimental Study of the Cyclic Variability in Spark Ignition Engines
Annotation ability available
Sector:
Language:
English
Abstract
Cyclic Variability has long been recognized as limiting the range of operating conditions of spark ignition engines, in particular, under lean and highly diluted operation conditions. Previous studies have shown that if cyclic variability could have been eliminated, there would be a 10% increase in the power output for the same fuel consumption. The cyclic variability results also in high level of variations in the engine speed which is interpreted as poor driveability. At full load, some of cycles tend to knock, while other may not have complete combustion by the time the exhaust valve opens.
An experimental study has been performed in order to evaluate the relative contribution of several relevant parameters on the cyclic variability in spark ignition engines. The cyclic variability has been examined via five major different pressure-related identifier, i.e. Pmax, θPmax, IMEP, (dp/dθ)max and θ(dp/dθ)max. Due to their high sensitivity to small fluctuation in the operation conditions, the two latter were found to be problematic in the characterization of the cyclic variability. The identifier (dp/dθ)max was found to be highly correlated to Pmax.
MBT ignition resulted in minimal cyclic variability. Variations in the ignition timing were found, however, to be less important under early ignition condition than under retarded ignition condition. The standard deviation of the spark jitter was found to be around 1.7 degrees and therefore cannot be ignored. Noticeable cyclic variations were observed also under motoring conditions which indicated that the role of the valves and rings leakage cannot be neglected.
The spark energy and spark duration were found to be less important than suggested in the literature. On the Contrary, the spark plug kind and its orientation were found to be very significant in determining the cyclic variability. This supports the idea that random fluctuations in the flow field due to the turbulence of the flow in the cylinder are important. These spatial fluctuations, that are also time-dependent, contribute to the imperfect mixing of the cylinder content, partial stratification, random convection of the spark kernel away from the electrodes, random heat transfer from the burning kernel to the spark electrodes, etc.
Authors
Topic
Citation
Ozdor, N., Dulger, M., and Sher, E., "An Experimental Study of the Cyclic Variability in Spark Ignition Engines," SAE Technical Paper 960611, 1996, https://doi.org/10.4271/960611.Also In
References
- Young, M.B. “Cyclic Dispersion in the Homogeneous- Charge Spark-Ignition - A Literature Survey” SAE paper 810020 1981
- Ozdor, N. Dulger M. Sher, E. “Cyclic Variability in Spark Ignition Engines - A Literature Survey” SAE paper 940987 1994
- Hamai, K. Kawajiri, H. Ishizuka, T. Nakai, M. “Combustion Fluctuation Mechanism Involving Cycle-to-Cycle Spark Ignition Variation Due to Flow Motion in S.I. Engines” 21st Symposium (International) on Combustion 1986
- De Socte, G. C. “Propagation behavior of spark ignited flames in earl stages” IMechE-Combustion in Engineering 1 93 100 1983
- Dulger, M. Sher E. “Experimental Study on Spark Ignition of Flowing Combustible Mixtures” SAE paper 951004 1995
- Sztenderowicz, M.L. Heywood, J.B. “Cycle-to-Cycle IMEP Fluctuations in a Stoichiometrically-Fueled S.I. Engine at Low Speed and Load” SAE paper 902143 1990
- Hill, P.G. “Cyclic Variation and Turbulence Structure in Spark-Ignition Engines” Combustion and Flame 72 73 89 1988
- Pundir, B.P. Zvonow, V.A. Gupta, C.P. “Effect of Charge Non Homogeneity on Cycle-by-Cycle Variation in Combustion in SI Engines” SAE paper 810774 1981
- Weaver, C.E. Santavicca, D.A. “Correlation of Cycle-Resolved Flame Kernel Growth and Cylinder Pressure in an Optically Accessible Engine” SAE paper 922171 1992
- Pischinger, S. Heywood, J.B. “A Study of Flame Development and Engine Performance with Breakdown Ignition Systems in a Visualization Engine” SAE paper 880518 1988
- Stone, C.R. Brown, A.G. Beckwith, P. “A turbulent Combustion Model Used To Give Insight Into Cycle-by-Cycle Variation in Spark Ignition Engine Combustion” Proceeding of the Institution of Mechanical Engineers, Combustion in Engines International Conference IMechE 1992
- Shen, H. Jiang, D. “Investigation on the Flame Initiation and Early Development in a Spark Ignition Engine” SAE paper 922239 1992
- Belmont, M.R. Hancock, M.S. Buckingham, D.J. “Statistical Aspect of Cyclic Variability” SAE paper 860324 1986
- Pischinger, S. Heywood, J.B. “How Heat Losses to the Spark Plug Affect Flame Kernel Development in an SI-Engine” SAE paper 900021 1990
- Arcoumanis, C. Bae, C-S. “Visualization of Flow/Flame Interaction in a Constant Volume Combustion Chamber” SAE paper 930868 1993
- Mantel, T. “Three Dimensional Study of Flame Kernel Formation Around Spark Plug” SAE paper 920587 1992
- Douaud, A. De Soete, G. Henault, C. “Experimental Analysis of the Initiation and Development of Part-Load Combustion in Spark-Ignition Engines” SAE paper 830338 1983