Aerodynamic Devices PDF Print E-mail

A significant factor affecting fuel use is aerodynamic resistance, commonly known as drag.  Drag is the force that resists movement through a liquid or gas (like air).

Studies by RMI and others have shown that drag is a large factor in fuel use and a reduction in drag will reduce fuel use in both urban and highway speeds. For tractor trailer combinations about 70% of drag is due to the trailer.   

drag diagram
Source: Presentation by Richard M. Wood, to Mid-Atlantic Regional Air Management Association

A state of the art study by the US Lawrence Livermore Labs (pdf) analyzed in detail the impact of drag on fuel efficiency in large tractor-trailer combinations.  Using supercomputers the Lab was able to develop a computer simulation of air flows between the tractor-trailer (see a below) and at the back end of a trailer (b below).  Using different technologies to smooth out this air flow will reduce drag and fuel use. 

 

trailer drag illustration

Some of the devices that reduce drag include:

Tractor

  • Low drag bumpers
  • Special wheel flaps
  • Wake boards
  • Aerodynamic mirrors
  • Centre and rear chassis fairings
  • Under-hood air cleaners
  • Full roof fairings

Trailer

  • Tractor-trailer gap fairings
  • Trailer side skirts
  • Trailer tails (pdf)
aerodynamic mirror
Aerodynamic mirror design

Many OEM and aftermarket manufacturers are selling these devices today.

trailer with gap fairing trailer skirt
 
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