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A Model of Quench Layer Entrainment During Blowdown and Exhaust of the Cylinder of an Internal Combustion Engine
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English
Abstract
An aerodynamic model of the entrainment of the head wall quench layer during blowdown and exhaust of an internal combustion engine has been developed. The model may be used to calculate the time resolved concentration and mass flowrate of hydrocarbons (HC) in the exhaust, from a knowledge of engine geometry and operating conditions. It predicts that the area As from which HC are swept will be proportional to the cube root of the ratio of the quench layer thickness δq to the thickness of the viscous boundary layer δv. Since the mass of HC emitted is proportional to the product of the HC density ρHC, the area As and the thickness δq, the HC emissions will be proportional to the product ρHC δq4/3 and this is the most important factor determining the emissions.
The model also predicts that the time dependence of the HC mass flowrate will depend relatively strongly on the pressure ratio p4/pe across the exhaust valve when it opens: in an unthrottled engine virtually all the head wall HC exit during blowdown; in a heavily throttled engine the HC are emitted more or less uniformily during the exhaust stroke.
It is expected that the model will be useful both for interpreting experimental measurements of HC emissions and for predicting HC emissions from practical engines. Comparisons of the results obtained to date with the available experimental data shows good agreement.
Authors
Citation
Hicks, R., Probstein, R., and Keck, J., "A Model of Quench Layer Entrainment During Blowdown and Exhaust of the Cylinder of an Internal Combustion Engine," SAE Technical Paper 750477, 1975, https://doi.org/10.4271/750477.Also In
References
- Daniel W. A. “Flame Quenching at the Wall of a Internal Combustion Engine” Sixth Symposium (International) on Combustion, Yale University, New Haven, Conn. New York Reinhold Publishing Co. 1956
- Daniel W. A. Wentworth J. T. “Exhaust Gas Hydrocarbons - Genesis and Exodus” SAE Technical Progress Series 6 “Vehicle Emissions” New York Society of Automotive Engineers, Inc. 1964
- Tabaczynski R. J. Heywood J. B. Keck J. C. “Time-Resolved Measurements of Hydrocarbon Mass Flowrate in the Exhaust of a Spark Ignition Engine” SAE Paper 720112 Automotive Engineering Congress Detroit, Mich. January 1972
- Tabaczynski R. J. Hoult D. P. Keck J. C. “High Reynolds Number Flow in a Moving Corner” J. Fluid Mechanics 42 June 1970 249 255
- Schlichting H. “Boundary Layer Theory”, 6th Edition 152 McGraw-Hill Book. New York 1968
- Friedman R. Johnston W. C. “Pressure Dependence of Quenching Distance of Normal Heptane, Iso-Octane, Benzene, and Ethyl Ether Flames” Jrl. of Chemical Physics 20 1952 919 920
- Agnew J. T. Green K. A. “Quenching Distances of Propane-Air Flames in a Constant-Volume Bomb” Combustion and Flame 15 1970 189 191
- Friedman R. Johnston W. C. “The Wall-Quenching of Laminar Propane Flames as a Function of Pressure, Temperature, and Air-Fuel Ratio” Jrl. Applied Physics 21 1950 791 795
- Ellenberger J. M. Bowlus D. A. “Single Wall Quench Distance Measurements” 1971 Technical Session, Central States Section Combustion Institute March 1971
- Ferguson C. R. Danieli G. A. Heywood J. B. Keck J. C. “Time Resolved Measurements of Exhaust Composition and Flow Rate in a Wankle Engine” Paper 750024 SAE Automotive Engineering Congress Detroit January 1975