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Measurement and Modeling of Thermal Flows in an Air-Cooled Engine
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Abstract
Control of the flow of thermal energy in an air-cooled engine is important to the overall performance of the engine because of potential effects on engine performance, durability, design, and emissions. A methodology is being developed for the assessment of thermal flows in air-cooled engines, which includes the use of cycle simulation and in-cylinder heat flux measurements. The mechanism for the combination of cycle simulation, the measurement of in-cylinder heat flux and wall temperatures, and comparison of predicted and measured heat flux in the methodology is presented.
The methodology consists of both simulation and experimental phases. To begin, a one-dimensional gas dynamics code (WAVE) has been used in conjunction with a detailed in-cylinder flow and combustion model (IRIS) in order to simulate engine operation in a variety of operating conditions. The methods used to apply the model to the air-cooled engine case are described in detail. Sensitivity studies have been performed demonstrating the effects of unknown parameters of importance to the model predictions, but not available from experiments. After the engine model has been tuned to produce the measured pressure history, it is then used to predict the in-cylinder heat flux.
Experimentally, a thermopile-based heat flux sensor has been used to measure in-cylinder surface heat flux and surface temperatures. Cycle-resolved heat flux and surface temperature measurements have been obtained over a range of air/fuel ratios. It is observed that the individual cycle heat flux varies substantially from one cycle to the next. The amount of variability in the instantaneous flux was a strong function of air/fuel ratio, with the least variability occurring near the peak power point. Peak wall temperatures were observed at the peak power point (298.5°C), with some reduction further on the rich side of stoichiometric, and substantial reductions on the lean side (>279.8°C at A/F = 15.75.)
Comparison of the model predictions of the instantaneous in-cylinder heat flux with that measured shows that the measured heat flux tends to peak earlier in the burn, and the predicted value for the integrated heat flux over the cycle is about 15% higher than that measured.
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Tillock, B. and Martin, J., "Measurement and Modeling of Thermal Flows in an Air-Cooled Engine," SAE Technical Paper 961731, 1996, https://doi.org/10.4271/961731.Also In
Design, Modeling, and Emission Control for Small Two- and Four-Stroke Engines
Number: SP-1195; Published: 1996-08-01
Number: SP-1195; Published: 1996-08-01
References
- Heywood, J. B. Internal Combustion Engine Fundamentals McGraw-Hill, Inc. New York 1988
- Stone, R. Introduction to Internal Combustion Engines 2nd SAE, Inc. Warrendale, PA 1992
- Gruden D. Kuper P. F. “Heat Balance of Modern Passenger Car SI Engines” XIXth International Symposium, International Centre for Heat and Mass Transfer, Heat and Mass Transfer in Gasoline and Diesel Engines Dubrovnik August 1987
- Whitehouse N. D. “An Estimate of Local Instantaneous Condition in a Diesel Engine” 1st International Conference on Heat and Mass Transfer in Gasoline and Diesel Engines Dubrovnik 1987
- Yang, J. Martin, J. K. “Predictions of the Effects of High Temperature Walls, Combustion, and Knock on Heat Transfer in Engine-Type Flows,” SAE Paper 900690 1990
- Yan, J. Borman, G. “Analysis and In-Cylinder Measurement of Particulate Radiation Emissions and Temperature in a Direct Injection Diesel Engine,” SAE Paper 881315 1988
- Baker, D.M. Assanis, D. N. “A Methodology for Coupled Thermodynamic and Heat Transfer Analysis of a Diesel Engine,” Appl. Math. Modeling 18 590 November 1994
- Morel, T. Keribar, R. “A Model for Predicting Spatially and Time Resolved Convective Heat Transfer in Bowl-in-Piston Combustion Chambers,” SAE 850204 1985
- Morel, T. Rackmil, C. I. Keribar, R. Jennings, M. J. “Model for Heat Transfer and Combustion in Spark Ignited Engines and Its Comparison with Experiments,” SAE 880198 1988
- Bonneau, R. J. Cunningham, M. J. Martin, J. K. “Emissions and Combustion Characteristics from Two Fuel Mixture Preparation Schemes in a Utility Engine,” SAE Paper 952081 1995
- Hager, J. M. Simmons, S. Smith, D. Onishi, S. Langley, L. W. Diller, T. E. “Experimental Performance of a Heat Flux Microsensor,” Transactions of the ASME 113 246 250 April 1991
- Holmberg, D. G. Diller, T. E. “High-Frequency Heat Flux Sensor Calibration and Modeling,” Unsteady Flows in Aeropropulsion 40 ASME 1994
- Alkidas, A.C. Myers, J.P. “Transient Heat Flux Measurements in the Combustion Chamber of a Spark Ignition Engine,” J. Heat Transfer, ASME Trans. 104 62 1982