This content is not included in
your SAE MOBILUS subscription, or you are not logged in.
Effects of Ignition Timing and Air-Fuel Ratio on In-Cylinder Heat Flux and Temperatures in a Four-Stroke, Air Cooled, Homogeneous Charge Engine
Technical Paper
1999-01-0284
ISSN: 0148-7191, e-ISSN: 2688-3627
Annotation ability available
Sector:
Language:
English
Abstract
In-cylinder heat flux and temperature measurements were obtained in an air-cooled four-stroke utility engine for a range of air-fuel ratios. For these measurements, the magnitude of the integrated heat flux peaked at the stoichiometric air-fuel ratio, with an approximately linear decrease on either side of stoichiometric. Advancing the spark generally increased the magnitude of the integrated heat flux. Evaluation of the Brake Specific Integrated Heat Flux (BSIHF) mitigated these trends, and, the effects of changes in timing were eliminated for some operating conditions
Examination of the BSIHF from the compression and expansion stroke showed behavior mimicking the full cycle BSIHF. However, the fraction of the total flux contributed by this portion of the cycle varied greatly from approximately 98% of the total to approximately 75% of the total. In addition, BSIHF for the gas exchange portion of the cycle exhibited much different trends than the full cycle BSIHF, with the peak values occurring with mixtures lean of stoichiometric and retarded timings.
Steady-state values of cylinder head temperatures near the surface were also obtained to observe how air-fuel ratio and spark timing would affect temperatures. Different trends were noticed depending on the location of the thermocouple measurement. For example, measurements of surface temperature near the spark plug had trends similar to that observed for the BSIHF. Temperatures varied by more than 70°C at this location, depending on air-fuel ratio and timing. In contrast, temperature measurements in the valve bridge were constant for air-fuel ratios richer than stoichiometric. Cylinder head temperatures near the cylinder wall displayed yet different behavior, with no apparent effect from ignition timing changes.
Recommended Content
| Technical Paper | Correlation of Air Fuel Ratio with Ionization Signal Metrics in a Multicylinder Spark Ignited Engine |
| Technical Paper | The Lean Hunting Phenomenon in Gasoline Engines |
| Technical Paper | Wide Range Air-Fuel Ratio Control System |
Authors
Citation
Boyce, B., Martin, J., Poehlman, A., and Shears, D., "Effects of Ignition Timing and Air-Fuel Ratio on In-Cylinder Heat Flux and Temperatures in a Four-Stroke, Air Cooled, Homogeneous Charge Engine," SAE Technical Paper 1999-01-0284, 1999, https://doi.org/10.4271/1999-01-0284.Also In
References
- Borman, G.L. Nishiwaki, “Internal-Combustion Engine Heat Transfer,” Prog. Energy Combust. Sci. 13 1 46 1987
- Boyce, B.P. “Effect of Air Fuel Ratio and Ignition Timing on Thermal Loading and Engine Performance of a Spark Ignited, Homogeneous Charged, Four Stroke, Air-Cooled Engine,” University of Wisconsin Madison 1998
- Tillock, B.. Martin, J.K. “In-Cylinder Heat Flux in a Four Stroke, Air-Cooled, Spark-Ignited Engine with fixed Timing,” SAE Paper 972708 1997
- Tillock B. R. “Thermal Analysis Methodology for Air-Cooled Engines,” Mechanical Engineering Department, University of Wisconsin Madison 1997
- Bonneau, R.J. “Development of a Homogeneous Mixture System and Comparison with Carbureted Utility Engine Emissions and Performance,” Mechanical Engineering Department, University of Wisconsin Madison 1994
- Spindt, R.S. “Air-Fuel Ratios from Exhaust Gas Analysis” SAE Paper 650607 1965
- Tillock, B. R. Martin, J.K. “Measurements and Modeling of Thermal Flows in an Air-Cooled Engine” SAE Paper 961713 1996
- Boyce, B. P. Martin, J.K “Energy Flow Predictions in an Air-Cooled Engine” 29-2 Proceedings of the 19th Annual Fall Technical Conference of the ASME Internal Combustion Engine Division 1997