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Aerodynamic Drag of Engine-Cooling Airflow With External Interference
ISSN: 0148-7191, e-ISSN: 2688-3627
Published March 03, 2003 by SAE International in United States
Annotation ability available
This report examines the aerodynamic drag and external interference of engine cooling airflow. Much of the report is on inlet interference, a subject that has not been discussed in automotive technical literature. It is called inlet spillage drag, a term used in the aircraft industry to describe the change in inlet drag with engine airflow. The analysis shows that the reduction in inlet spillage drag, from the closed front-end reference condition, is the primary reason why cooling drag measurements are lower than would be expected from free stream momentum considerations. In general, the free stream momentum (or ram drag) is the upper limit and overstates the cooling drag penalty. An analytical expression for cooling drag is introduced to help the understanding and interpretation of cooling drag measurements, particularly the interference at the inlet and exit. Empirical thrust coefficients, which represent the interferences, are introduced as a practical representation of the interaction to the exterior pressure distribution. Comparisons to experimental measurements on three vehicles are presented to illustrate the concepts.
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CitationWilliams, J., "Aerodynamic Drag of Engine-Cooling Airflow With External Interference," SAE Technical Paper 2003-01-0996, 2003, https://doi.org/10.4271/2003-01-0996.
SAE 2003 Transactions Journal of Passenger Cars - Mechanical Systems
Number: V112-6 ; Published: 2004-09-15
Number: V112-6 ; Published: 2004-09-15
- Barnard, R. H., “Theoretical and experimental investigation of the aerodynamic drag due to automotive cooling systems”, Proc Institute of Mechanical Engineers Vol. 214 Part D. IMechE 2000
- Barnard, R. H. and Ledakis N., “Physical modelling and optimization of radiator cooling flow systems”, Proc. 2nd MIRA Conference on Vehicle Aerodynamics, October 1998.
- Santer, Robert M. and Gleason Mark E., “The Aerodynamic Development of the Probe IV Advanced Concept Vehicle”, SAE report 83100, June 1983
- Renn, V. and Gilhaus A., “Aerodynamics of vehicle cooling systems”, Proc. 6th Colloquium on Industrial Aerodynamics and Road Vehicle Aerodynamics, Fachhochschule, Aachen, 1985, pp. 303-311.
- Carr, G. W., “The Influence of Engine-Cooling Airflow on Car performances and Stability”, IMechE Report C496/079, 1995
- Hoerner S. F., Fluid Dynamic Drag, Hoerner Fluid Dynamics, P.O. Box 342, Brick Town N. J. 08723, 1965, pp. 9-1 and 9-2.
- Wiedemann, Jochen, “The Influence of Ground Simulation and Wheel Rotation on Aerodynamic Drag Optimization - Potential for Reducing Fuel Consumption”, SAE report 960672, February 1996.
- Soja, H. and Wiedemann J., “The interference between internal and external flow on road vehicles”, Ingenieurs d'Automobile, September 1987, pp. 101-105.
- Kuchemann, D. and Weber J., Aerodynamics of Propulsion, McGraw-Hill Company, 1953, pp. 59-65.
- Hucho W-H., Aerodynamics of Road Vehicles, 4th ed., SAE International, 1998, pp. 197-201.
- Ohshima, T., Hamatani K., Ninoyu M., and Nakagawa K., “Influence of the cooling airflow outlet on the aerodynamic characteristics”, JSAE Review 19 (1998) 137-142.
- Seddon, J. and Goldsmith E. L., Intake Aerodynamics, AIAA Education Series, 1985, pp. 217-220.
- Williams, J. E., Hackett J. E., Oler J. W., and Hammer L., “Water Flow Simulation of Automotive Underhood Airflow Phenomena”, SAE 910307, February 1991.
- Williams, Jack, Oler Walt, and Karanth Dinakara, “Cooling Inlet Aerodynamic Performance and System Resistance”, SAE report 2002-01-0256, March 2002.
- Williams, Jack and Vemaganti Guru, “CFD Quality - A Calibration Study for Front-End Cooling Airflow”, SAE 980039, February 1998.