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Analysis and Measurements of Cyclic Variations and Emissions of Single Cylinder Two Stroke Engines at Low Loads
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Abstract
Cyclic variation is a serious problem for two stroke engines at low load conditions. Misfire and partially burned cycles occur and the unburned hydrocarbons in the exhaust are extremely high. The occurrence of variations seems random. However, there are some rules behind this seemingly chaotic process. The combustion of one cycle is affected by the concentration of residual gas in the cylinder, which is the result of the scavenging process of pre-cycles. An engine cycle model has been developed in a previous paper which can simulate the cyclically varied process and generate chaotic or multi-cycle periodic engine performance. In this paper, the engine cycle model was refined, and the calculated results of misfire rates and the HC and the CO emissions were compared with measured data.
The residual gas concentration in the cylinder prior to ignition was used as the criterion to determine a successful ignition in the previous model. In this paper, an energy balance in the flame kernel at ignition point was used to replace the old criterion. Results of simulation showed that these two criteria are equivalent at some engine conditions. Furthermore, a flexible scavenging model was used in this paper which can switch between the perfect mixing model and the perfect displacement model or any combination of these two models.
Results of calculations were compared with the measured data at low load engine conditions. The misfire rate and the short circuit ratio agree well with experimental data in trend. The trends of variation for the HC and the CO emissions while equivalence ratio was varied are consistent with the measured data. However, the magnitudes of calculated emissions are about 30% higher than the measured data.
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Citation
Lu, J. and Lee, Y., "Analysis and Measurements of Cyclic Variations and Emissions of Single Cylinder Two Stroke Engines at Low Loads," SAE Technical Paper 960746, 1996, https://doi.org/10.4271/960746.Also In
References
- Young M.B. “Cyclic Dispersion in the Homogeneous-Charge Spark Ignition Engine - A Literature Survey” SAE Paper 810020 1980
- Tsuchiya K. Nagai Y. Gotoh T. “A Studs, of Irregular Combustion in 2-Stroke Cycle Gasoline Engines” SAE Paper 830091 1983
- Martin J.K. Plee S.L. Remboski. D.J. Jr. “Burn Modes and Prior-cycle Effects on Cyclic Variations in Lean-burn Spark-ignition Engine Combustion” SAE Paper 880210 1988
- Daily J.W. “Cycle-to-cycle Variations: A Chaotic Process?” SAE Paper 870165 1987
- Lu Jau-Huai Wang Chen-Meanng “Studies on the Cyclic Variations of Single Cylinder Two-stroke Engines - Cycle Analysis” SAE Paper 950225 1995
- Annand W.J. “The Estimation of Flame Propagation Rates in Routine Computer Synthesis of Spark-Ignition Engine Combustion” IMechE 1983
- Tabazynski R.J. Ferguson C.R. “A Turbulent Entrainment Model for Spark-Ignition Engine Combustion” SAE Paper 770647 1977
- Hong Rong-Fang “Investigation of Combustion Characteristics on a Two-Stroke Cycle S.I. Engine with an Air-Assisted Fuel Injection System” National Cheng-Kung University Taiwan 1994
- Anderson R.W Lim M.T. “Investigation of Misfire in a Fast Bum Spark Ignition Engine” Combust, Sci, and Tech. 43 183 196 1985
- Hacohen J. Belmont M.R. Thurley R.W.F. Thomas J.C. Morris E.L. Buckingham D.J. “Experimental and Theoretical Analysis of Flame Development and Misfire Phenomena in a Spark-Ignition Engine SAE Paper 920415 1992