Wind and Structures

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Aerodynamics of an intercity bus

  • Sharma, Rajnish (Department of Mechanical Engineering, The University of Auckland) ;
  • Chadwick, Daniel (Department of Mechanical Engineering, The University of Auckland) ;
  • Haines, Jonathan (Department of Mechanical Engineering, The University of Auckland)
  • Received : 2006.10.17
  • Accepted : 2008.05.02
  • Published : 2008.08.25
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Abstract

A number of passive aerodynamic drag reduction methods were applied separately and then in different combinations on an intercity bus model, through wind tunnel studies on a 1:20 scale model of a Mercedes Benz Tourismo 15 RHD intercity bus. Computational fluid dynamics (CFD) modelling was also conducted in parallel to assist with flow visualisation. The commercial CFD package $CFX^{TM}$ was used. It has been found that dramatic reductions in coefficient of drag ($C_D$) of up to 70% can be achieved on the model using tapered and rounded top and side leading edges, and a truncated rear boat-tail. The curved front section allows the airflow to adhere to the bus surfaces for the full length of the vehicle, while the boat-tails reduce the size of the low pressure region at the base of the bus and more importantly, additional pressure recovery occurs and the base pressures rise, reducing drag. It is found that the CFD results show remarkable agreement with experimental results, both in the magnitude of the force coefficients as well as in their trends. An analysis shows that such a reduction in aerodynamic drag could lead to a significant 28% reduction in fuel consumption for a typical bus on intercity or interstate operation. This could translate to a massive dollar savings as well as significant emissions reductions across a fleet. On road tests are recommended.

Keywords

References

  1. Camara, E. and Girardi, R. (1995), "On the aerodynamic analysis of a bus model", Society of Automotive Engineers Brazil, 952265E.
  2. Carr, G. W., Cooper, K. R., Garry, K. P., Gerhardt, H. J. and Whitbread, R. (1986), "A comparison of aerodynamic drag measurements on model trucks in closed-jet and open-jet wind tun-nels", J. Wind Eng. Ind. Aerodyn., 22, 299-316. https://doi.org/10.1016/0167-6105(86)90093-0
  3. Cooper, K. R. (1985), "The effect of front-edge rounding and rear-edge shaping on the aerodynamic drag of bluff vehicles in ground proximity", Society of Automotive Engineers, Technical Paper SAE850288.
  4. Cooper, K. R. (2003), "Truck aerodynamics reborn-lessons from the past", Society of Automotive Engineers, 2003-01-3376.
  5. Englar, R. J. (2000), "Development of pneumatic aerodynamic devices to improve the perform ance, economics, and safety of heavy vehicles", Society of Automotive Engineers, 2000-01-2208.
  6. Filippone, Dr A. (2003), Advanced Topics in Aerodynamics, Retrieved June 2004, from: http://aerodyn.org/
  7. Fletcher, C. A. J and Stewart, G. D. H. (1986), "Bus drag reduction by the trapped vortex concept for a single bus and two buses in tandem", J. Wind Eng. Ind. Aerodyn., 24, 143-168. https://doi.org/10.1016/0167-6105(86)90004-8
  8. Gao, Li. Yinsan, Chen. Gong, Chunyuan. and Gao, Yanling. (1995), "Automobile model scale wind-tunnel test by means of aeronautical wind-tunnel", Society of Automotive Engineers, 950999.
  9. Hucho, W. H., Janssen, L. J. and Emmelmann, S. J. H. (1976), "The optimisation of body details-a method of reducing aerodynamic drag of road vehicles", Society of Automotive Engineers, 760185.
  10. Kim, M., Kuk. J. and Chyum, I. (2002), "A numericial simulation on the drag reduction of large sized bus using rear spoiler", Society of Automotive Engineers, 2002-01-3070.
  11. Kral, L. D. (1998), "Recent experience with different turbulence models applied to the calculation of flow over aircraft components", Progress in Aerospace Science, 34, 481-541. https://doi.org/10.1016/S0376-0421(98)00009-8
  12. Kubo, Y., Yukoku, E., Modi, V. J., Yamaguchi, E., Kato, K. and Kawamura, S. (1999), "Control of flow separation from leading edge of a shallow rectangular cylinder through momentum in-jection", J. Wind Eng. Ind. Aerodyn., 83, 503-514. https://doi.org/10.1016/S0167-6105(99)00097-5
  13. Lee, C. J. (2003), Aerodynamic Drag Reduction of Buses, Mechanical Engineering Project, School of Engineering, The University of Auckland.
  14. LTSA. (2004a), Fact Sheet 11, Retrieved March 2004, from www.ltsa.govt.nz.factsheets/11.html
  15. LTSA. (2004b), Amendment Regulations-Heavy Vehicles Speed Limits, Retrieved September 21, 2004 from: http://www.ltsa.govt.nz/legislation/hvy-veh-speed-limits-qa.html
  16. McGuinness, H. J. (2004/2005), Air Resistance: Distinguishing Between Laminar and Turbulent Flow, Retrieved September 18, 2004, July 2005, from: http://academic.reed.edu/physics/courses/phys100/Lab20Manuals/Air20 Resistance/Air.Resistance.pdf
  17. Mercedes Benz Omnibus Website, Retrieved June 2004, from: www.mercedes-benz.com/e/ecar/omnibus/default.htm
  18. Meyer, R. and Saltzman, E. (1999), "A Reassessment of Heavy Duty Truck Aerodynamic Design Features and Priorities", NASA Technical Publications, TP-1999-206574, 1-33.
  19. Modi, V. J., Hill, S. St, and Yokomizo, T. (1995), "Drag reduction of trucks through boundary-layer control", J. Wind Eng. Ind. Aerodyn., 55/56, 583-594.
  20. Munshi, S. R. and Modi, V. J. (1997), "Aerodynamics and dynamics of rectangular prisms with moving momentum injection", J. Fluids Struct., 11, 873-892. https://doi.org/10.1006/jfls.1997.0108
  21. Oram, W. J. (2003), Aerodynamic Drag Reduction of Buses, Mechanical Engineering Project, School Of Engineering, the University of Auckland.
  22. Perzon, S., Janson, J. and Hoglin, L. (1999), "On comparisons between CFD methods and wind tunnel tests on a bluff body", Society of Automotive Engineers, 1999-01-0805.
  23. Prasad, A. and Williamson, C. H. K. (1997), "A method for the reduction of bluff body drag", J. Wind Eng. Ind. Aerodyn., 69-71, 155-167. https://doi.org/10.1016/S0167-6105(97)00151-7

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