Publications:Estimation of Combustion Variability Using In-Cylinder Ionization Measurements


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Title Estimation of Combustion Variability Using In-Cylinder Ionization Measurements
Author Stefan Byttner and Thorsteinn Rögnvaldsson and Nicholas Wickström
Year 2001
PublicationType Conference Paper
Conference SAE International Fall Fuels & Lubricants Meeting & Exhibition, September 2001, San Antonio, TX, USA, Session: Experimental Investigation of SI Engines (Part A&B)
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Abstract This paper investigates the use of the ionization current to estimate the Coefficient of Variation for the Indicated Mean Effective Pressure, COV(IMEP), which is a common variable for combustion stability in a spark-ignited engine. Stable combustion in this definition implies that the variance of the produced work, measured over a number of consecutive combustion cycles, is small compared to the mean of the produced work. The COV(IMEP) is varied experimentally either by increasing EGR flow or by changing the air-fuel ratio, in both a laboratory setting (engine in dynamometer) and in an on-road setting. The experiments show a positive correlation between COV(Ion integral), the Coefficient of Variation for the integrated Ion Current, and COV(IMEP), when measured under low load on an engine in a dynamometer, but not under high load conditions. On-road experiments show a positive correlation, but only in the EGR and the lean burn case. An approach based on individual cycle classification for real-time estimation of combustion stability is discussed.