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The Aerodynamic Drag of Cars Current Understanding, Unresolved Problems, and Future Prospects

  • W. -H. Hucho

Abstract

An introduction to the drag-related aerodynamics of cars is presented from a practitioner’s point of view. Both current understanding and unresolved problems are elucidated with the aid of examples from design work carried out on cars now on the road. Prior to discussing aerodynamic drag in detail, a brief outline is given of the entire field of vehicle aerodynamics, of the economic significance of drag, and of the constraints that have to be observed during design.

Subsequently, aerodynamic drag is classified by type. The mechanisms of external and internal drag are discussed. Attention is drawn to gaps in related knowledge, especially to induced drag. These more or less fundamental considerations are followed by the description of a method which has proved to be very effective during actual design work. This so-called optimization technique has been developed at Volkswagenwerk AG over the recent years. Some results achieved with the technique are presented.

Finally, today’s state of the art is placed in the context of a time history of vehicle aerodynamics. What has been achieved to date on production automobiles is compared with what is known to be attainable. This contrast should be viewed as a challenge, one that must be met by increased levels of research and development in vehicle aerodynamics.

Keywords

Drag Coefficient Drag Reduction Fuel Economy Aerodynamic Drag Pressure Drag 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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References

  1. Barth, R. (1956), Einfluss der Form und der Umstroemung von Kraftfahrzeugen auf Widerstand, Bodenhaftung und Fahrtrichtungshaltung, VDI-Zeitschrift, 98, pp. 1265–1312.Google Scholar
  2. Braess, H.-H., Burst, H., Hamm, L. & Hannes, R. (1975), Verbesserung der Fahreigenschaften durch Verringerung des aerodynamischen Auftriebes, ATZ, 77, pp. 119–124.Google Scholar
  3. Emmenthal, K.-D., & Hucho, W.-H. (1974), A Rational Approach to Automotive Radiator Systems Design, SAE 740088Google Scholar
  4. Flegl, H. (1974), Die Fahrleistungsgrenzen heutiger Rennwagen — elaeutert am Beispiel des Porsche 917/10 CAN-AM, Koll. Industrie Aerodynamik, Aachen, Part 3: Aerodynamik von Strassenfahrzeugen, pp. 141–152.Google Scholar
  5. Goetz, H. (1971), The Influence of Wind Tunnel Tests on Body Design, Ventilation and Surface Deposits of Sedans and Sportcars, SAE 710212.Google Scholar
  6. Hoerner, S. (1965), Fluid-Dynamic Drag, Published by the Author, Brick Town, N.J.Google Scholar
  7. Howell, J. (1974), Wake Properties of a Saloon Car, Koll. Industrie Aerodynamik, Aachen, Part 3: Aerodynamik von Strassenfahrzeugen, pp. 85–95.Google Scholar
  8. Hucho, W.-H. (1972), Einfluss der Vorderwagenform auf Widerstand, Giermoment und Seitenkraft von Kastenwagen, Zeitschrift fuer Flugwissenschaft, 20, pp. 341–351.Google Scholar
  9. Hucho, W.-H., Janssen, L. J., & Schwarz, G. (1975), The Wind Tunnel’s Ground Plane Boundary Layer — Its Interference with the Flow Underneath Cars, SAE 750066.Google Scholar
  10. Hucho, W.-H., Janssen, L. J. & Emmelmann, H.-J. (1976), The Optimization of Body Details — A Method for Reducing the Aerodynamic Drag of Road Vehicles, SAE 760185.Google Scholar
  11. Hucho, W.-H. (1976), Steigerung der Wirtschaftlichkeit von Kraftfahrzeugen durch geeignete Formgebung, to be published in Automobil Revue, Bern.Google Scholar
  12. Hurter, D. A. & Lee, W. D. (1975), A Study of Technological Improvements in Automobile Fuel Consumption, SAE 750005.Google Scholar
  13. Janssen, L. J. & Hucho, W.-H. (1973), Effect of Various Parameters on the Aerodynamic Drag of Passenger Cars, Advances in Road Vehicle Aerodynamics, Cranfield, UK, pp. 223–253.Google Scholar
  14. Kamm, W. (1969), Der Weg zum wirtschaftlichen autobahn-und strassentuechtigen Wagen, Strasse, 6, pp. 104–109.Google Scholar
  15. Klemperer, W. (1922), Luftwiderstandsuntersuchungen an Automobilmodellen, Zeitschrift f. Flugtechnik u. Motorluftschiffahrt, 13, pp. 201–206.Google Scholar
  16. Kramer, C., Gerhardt, H. J., Jaeger, E. & Stein, H. (1974), Windkanalstudien zur Aerodynamik der Fahrzeugunterseite, Koll. Industrie Aerodynamik, Aachen, Part 3: Aerodynamik von Strassenfahrzeugen, pp. 71–83.Google Scholar
  17. Morelli, A., Fioravanti, L., & Cogotti, A. (1976), The Body Shape of Minimum Drag, SAE 760186.Google Scholar
  18. Ohtani, K., Takei, M. & Sakamoto, H. (1972), Nissan Full-Scale Wind Tunnel — Its Application to Passenger Car Design, SAE 720100.Google Scholar
  19. Olson, M. E. (1976), Aerodynamic Effects of Front End Design on Automobile Engine Cooling Systems, SAE 760188.Google Scholar
  20. Schmidt, C. (1939), Fahrwiderstaende beim Kraftfahrzeug und die Mittel ihrer Verringerung, ATZ, 41, pp. 465–477 and pp. 498–510.Google Scholar
  21. Wallis, S. B. (1971), Ventilation System Aerodynamics — A New Design Method, SAE 710036.Google Scholar
  22. DIN 70030 (1968), Ermittlung des Kraftstoffverbrauch von Kraftfahrzeugen, Beuth Vertrieb, Koeln.Google Scholar

Copyright information

© Plenum Press, New York 1978

Authors and Affiliations

  • W. -H. Hucho
    • 1
  1. 1.Volkswagenwerk AGWolfsburgGermany

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