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Correlation of an Alternative Method for the Prediction of Engine Performance Characteristics with Measured Data
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Abstract
This paper presents confirmation of the accuracy of prediction of an engine simulation model. The experimental data used to compare with the output of the simulation model are from a single cylinder four-stroke cycle engine and from a single-cylinder two-stroke cycle engine; both engines are naturally aspirated and use spark- ignition. In addition, for the two-stroke cycle engine, the experimental data includes two cylinders with different scavenging characteristics which induce variations of performance characteristics of up to 20%. The fundamentals of the theoretical approach have been presented before to SAE (1)* and this paper extends that theory by providing a detailed discussion on the inclusion of measured scavenging characteristics to enable the simulation model to predict the mechanism of the in-cylinder gas exchange process. This permits the designer to use the simulation model to detail completely the internal geometry of an engine, its porting or valving, and its intake or exhaust ducting, and to deduce the overall performance characteristics such as power, torque, airflow or fuel consumption. Further detailed information is presented from the use of the simulation model on scavenging, trapping, and charging efficiencies and delivery ratio and also the pressures, temperatures, particle velocities, charge purities and densities as a function of time in various location throughout the engine. Such detailed insights into the internal gas dynamic and gas exchange characteristics are invaluable in that many are almost impossible to acquire experimentally and so they give the designer a ‘feel’ for the engine behaviour which could not otherwise be obtained.
The level of accuracy of correlation between measurement and calculation is such that the model can be used for design purposes with considerable confidence.
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Citation
Blair, G., "Correlation of an Alternative Method for the Prediction of Engine Performance Characteristics with Measured Data," SAE Technical Paper 930501, 1993, https://doi.org/10.4271/930501.Also In
References
- Blair G.P. “An Alternative Method for the Prediction of Unsteady Gas Flow through the Internal Combustion Engine” Society of Automotive Engineers International Off-Highway & Powerplant Congress Milwaukee, Wisconsin September 9-12 1991 SAE Paper No. 911850 137 162
- McConnell J.H. “Unsteady Gas Flow Through Naturally Aspirated Four-Stroke Cycle Internal Combustion Engines” The Queen's University of Belfast March 1974
- Kenny R.G. “Scavenging Flow in Small Two- Stroke Cycle Engines” The Queen's University of Belfast May 1980
- Blair G.P. McConnell J.H. “Unsteady Gas Flow Through a Four-Stroke Cycle Motorcycle Engine” SAE Farm, Construction and Industrial Machinery Meeting Milwaukee, Wisconsin September 1974 SAE Paper No. 740736 20
- Blair G.P. Kenny R.G. “Further 15. M.E.G. Sweeney, R.G. Kenny, G.B. Swann, G.P. Blair, “Computational Fluid Dynamics Applied to Two-Stroke Engine Scavenging” SAE Intnl. Off-Highway Vehicle Meeting Milwaukee, Wisconsin September 1985 SAE Paper No. 851519
- Sammons H. “A Single-Cycle Test Apparatus for the Studying ‘Loop-Scavenging’ in a Two-Stroke Engine” Proc.I.Mech.E. 161 1949 233 242
- Benson R.S. “The Thermodynamics and Gas Dynamics of Internal Combustion Engines” 1 2 Clarendon Press Oxford 1982
- Blair G.P. “Correlation of Theory and Experiment for Scavenging Flow in Two-Stroke Cycle Engines” Society of Automotive Engineers International Off-Highway & Powerplant Congress Milwaukee, Wisconsin September 12-15 1988 SAE Paper No. 881265
- Fleck R. Blair G.P. Houston R.A.R. “An Improved Model for Predicting Reed Valve Behaviour in Two-Stroke Cycle Engines” Society of Automotive Engineers, International Off-Highway & Powerplant Congress Milwaukee, Wisconsin September 14-17 1987 SAE Paper No. 871654 21
- Blair A.J. Blair G.P. “Gas Flow Modelling of Valves and Manifolds in Car Engines” Proc.I.Mech.E. International Conference on Computers in Engine Technology, University of Cambridge April 1987