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Steady-State Thermal Flows in an Air-Cooled, Four-Stroke Spark-Ignition Engine
ISSN: 0148-7191, e-ISSN: 2688-3627
Published March 01, 1999 by SAE International in United States
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Measurements of the instantaneous heat flux at three positions on the cylinder head surface, and the steady-state cylinder head temperatures at four positions on the cylinder head have been obtained. Engine tests were performed for a range of air-fuel ratios including regimes rich of stoichiometric, stoichiometric, and lean of stoichiometric. In addition, ignition timing was advanced in increments from 22° BTDC to 40° BTDC.
All tests were run with the throttle either fixed in the wide open position, or fixed in a position that produced 75% of the maximum power with the standard ignition timing and an air-fuel ratio of 13.5. This was done to ensure that changes in air mass flow rate were not influencing the results. In addition, all tests were performed with a fuel mixture preparation being provided by system designed to deliver a homogeneous premixed charge to the inlet port. This was done to ensure that mixture preparation issues were not confounding the results.
Based on the results of the heat flux measurements, a phenomenological model for spatially resolved predictions of the steady-state heat flux to the cylinder head was developed. This model allows prediction of the changes in steady state flux to the cylinder head occurring as a result of changes in air-fuel ratio, load, and ignition timing.
The phenomenological model was used in a finite element prediction of energy flows in the nonmoving parts of the engine. In-cylinder boundary conditions were determined using the phenomenological model. Comparisons of steady state temperatures predicted from the finite element analysis with those measured in the engine tests showed good agreement.
CitationBoyce, B., Martin, J., and Tillock, B., "Steady-State Thermal Flows in an Air-Cooled, Four-Stroke Spark-Ignition Engine," SAE Technical Paper 1999-01-0282, 1999, https://doi.org/10.4271/1999-01-0282.
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