Aerodynamic Forces on Trucks

1
Aerodynamic Forces on Trucks

• The loads on a single truck as a function of yaw
  angle and tractor-trailer gap spacing.
• The drag of two trucks in tandem at zero yaw.

M. Hammache F. Browand Ground Vehicle
Aerodynamics Lab
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Wind-Tunnel Truck Models
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Wind-Tunnel Truck Models
Netting over the cab
Six-component force balance support
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Tractor and Trailer with Gap
Rounded vertical leading edges on trailer
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Surface Maps
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Drag Forces

• Cab

• Trailer

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Fluctuations of Drag Forces
Cab
Trailer
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Side Forces
Cab
Trailer
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Fluctuations of Side Forces
Cab
Trailer
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Rolling Moments
Cab
Trailer
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Two Trucks in Tandem

• Previous results reported in SAE paper to be
  given in March 02.
• Drag savings for two trucks in tandem depends
  upon the drags of individual trucks in isolation,
  and upon which truck is leading.
• For completeness, we have made additional
  measurements over a large range of truck drag
  coefficients

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Effect of Front Bluntness
Blunt
CDTotal Cpf - Cpr CDsf .95
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Platoon Combinations
Flow
Front truck (CDF) Rear truck (CDR)
Rounded-Rounded
Rounded-Blunt
Blunt-Blunt
Blunt-Rounded
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Drag vs. Truck Separation
Blunt - Blunt
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Drag vs. Truck Separation
Blunt - Blunt
Blunt - Rounded
Rounded - Rounded
Rounded - Blunt
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Average Drag Summary
Total Drag/Total Drag in isolation
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Decreasing CD
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Average Drag Summary
Blunt - Rounded
Rounded - Rounded
Blunt - Blunt
Rounded - Blunt