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The Theoretical Development of Vehicle Engine Cooling Airflow Models Using Incompressible Flow Methods
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English
Abstract
A one-dimensional incompressible flow model covering the mechanisms involved in the airflow through an automotive radiator-shroud-fan system with no heat transfer was developed. An analytical expression to approximate the experimentally determined fan performance characteristics was used in conjunction with an analytical approach for this simplified cooling airflow model, and the solution is discussed with illustrations.
A major result of this model is a closed form equation relating the transient velocity of the air to the vehicle speed, pressure rise characteristics and speed of the fan, as well as the dimensions and resistance of the radiator. This provides a basis for calculating cooling airflow rate under various conditions.
The results of the incompressible flow analysis were further compared with the computational results obtained with a previously developed one-dimensional, transient, compressible flow model. The effects of the ambient air temperature, pressure, and heat transfer in the radiator on the cooling airflow rate were analyzed, and the use of an empirical formula to estimate the variation of the flow rate corresponding to heating of the air is presented and discussed.
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Chang, X., Chiang, E., and Johnson, J., "The Theoretical Development of Vehicle Engine Cooling Airflow Models Using Incompressible Flow Methods," SAE Technical Paper 910644, 1991, https://doi.org/10.4271/910644.Also In
References
- Chiang E. C. Huang G. P. C. Chang X. Johnson J. H. “A One-Dimensional Transient Compressible Flow Model for Cooling Airflow Rate Calculation” SAE Paper 900721 1990
- Chang X. “Prediction and Analysis of Truck Engine Cooling Airflow by Means of a One-Dimensional Transient Compressible Flow Model” Michigan Technological University 1990
- Chapman K. S. Johnson J. H. Chiang E. C. “The Enhancement and Validation of a Vehicle Engine Cooling System Simulation for a Heavy Duty Diesel Truck” SAE Paper 880601 1988
- Chapman K. S. Johnson J. H. Chiang E. C. “The Use of the Vehicle Engine Cooling System Simulation as a Cooling System Design Tool” SAE Paper 880600 1988
- Kays W. M. London A. L. Compact Heat Exchangers McGraw-Hill Book Co. 1981
- Williams J. “An Automotive Front-End Design Approach for Improved Aero-dynamics and Cooling” SAE Paper 850281 1985
- Chang X. Chiang E. C. Johnson J. H. Yang S. L. “The Dimensionless Correlation of Airflow for Vehicle Engine Cooling Systems” SAE Paper 910643 SAE International Congress & Exposition Feb. 1991
- Willoughby D. A. Carroll G. W. Williams J. Maxwell T. T. “A Quasi-Three-Dimensional Computational Procedure for Prediction of Turbulent Flow through the Front-end of Vehicles” SAE Paper 850282 1985