Vortex Generators

For years vortex generators where only frequently seen on owner-operator trucks.  Higher fuel prices have pushed several major fleets into trying these devices. Some drivers and fleets have used vortex generators on the back edge of the trailer create what they feel is less turbulence behind the trailer.

There are several suppliers of these systems.  Some are installed individually while others come in longer strips to allow several to be installed simultaneously.

Benefits

The improvement in fuel economy is small enough as to be below the noise level in test data.  None of these systems is EPA Smartway certified as of January 2018 and they are not available as a factory installed option from tractor or trailer manufacturers yet.

Many drivers report that using these devices have keep their trailers cleaner due to the revised air flow.

Some of the products have a side benefit to make them more visible at night.  Some glow in the dark while others have reflective surfaces to reflect headlights.

Handling and steering become easier if there is no wind buffeting of the trailer.

Challenges

These systems add a tiny amount of weight to the vehicle

These generators do not cost much money, but they may not save much fuel either.

Manufacturers

  • AirTabs
  • Eco Fins
  • VorBlade
  • V Spoilers

Decision-Making Tools

NACFE has developed several tools to help fleets make their decision about trailer aerodynamic devices.

  • The Confidence Matrix, informs fleets of NACFE’s confidence in the technology being studied vs. the payback the fleet should expect to receive from the technology
  • A simple payback calculator has been developed for aerodynamic devices
  • An appendix of SmartWay verified trailer aerodynamic devices can be found at the end of the full Confidence Report

Conclusions

  • Trailer aerodynamic devices save fuel. There is significant data showing fuel savings for the various technologies. The priority for device adoption by fleets is side, underbody and gap and then other devices. The EPA SmartWay program has made noteworthy progress since its inception in 2004, providing the industry with a structure for cataloging and ranking trailer aerodynamic devices. It should be considered a foundation for further improvement in performance evaluation.
  • Devices have matured and will continue to improve. Skirts have become lighter, less expensive and more robust improving their payback. Other devices are maturing but need continued development to improve their total cost of ownership. There is a widespread recognition of the further improvements and efficiency gains that stand to be achieved in trailer aerodynamics.
  • Unique challenges exist. These include trailer-to-tractor ratio which limit the miles per trailer, some cases of the trailer aerodynamics purchaser not buying the fuel and lastly, devices should be driver passive: no driver interaction is required to deploy or stow. There are solutions to these challenges.
  • Performance for each fleet is difficult to determine. Performance of any device is subject to many variables and each operator will likely have their own experiences. But the standardized test methods are directionally useful in evaluating different devices and combinations of devices. A range of products are now readily available that offer proven savings. As these products have matured, so has the industry’s understanding of the need for improvements in the way fuel efficiency performance is measured and allocated. Advances in test and analysis continue to be made, but the tools available today tend to report performance judged under controlled, focused, operating conditions rather than representing the full range of operations possible in industry. Although most fleets can measure tractor efficiency very closely, they do not have the tools to monitor the trailer efficiency at all.
  • Regulations will drive greater adoption. GHG Phase II and CARB rules will drive much greater adoption of trailer aero devices in the near future, taking them from being add-on options to being standard equipment. The Greenhouse Gas Phase II emissions rules are likely to significantly influence trailer aerodynamic technology adoption. The rules have been released but await litigation proceedings before they can be implemented at this time. California’s existing CARB rules, which are linked to EPA SmartWay designated technologies, are already influencing some investment decisions. However, the primary motivation for aerodynamic technology investment remains a business one, with fleets demanding a two year or less payback for technologies.
  • Aerodynamic devices must work without driver intervention. History has shown that devices that need driver intervention — such as first generation trailer tails — are not effective solutions as drivers do not deploy them 100% of the time. Second generation rear devices are addressing some of the challenges of the earlier versions of those devices. Future aerodynamic devices must work without needing driver involvement in their operation.