Old technology could get a new lease on life as fuel prices skyrocket.
In the late 1990s, researchers at Georgia Tech Research Institute began drawing from 1980s aerospace technology to develop several diesel-saving aerodynamic tricks for 18-wheelers. Their results were announced in 2005. Back then, however, diesel was cheap so the tricks never became part of the trade.
Today, the leader of all that research said the trucking companies are calling him.
"The dramatic increase in diesel prices has led the trucking industry to reconsider aerodynamic fuel efficiency improvements that might not have been cost effective only a few years ago," said Georgia Tech's Robert Englar. "Though there are technical challenges ahead, we believe our techniques for improving fuel efficiency offer significant potential to reduce the impact of these fuel cost increases. Beyond the trucking industry, that would help consumers who see the effects of fuel costs in everything they buy."
What a drag
Englar's team, with support from the U.S. Department of Energy, came up with several simple solutions to reduce aerodynamic drag and improve fuel efficiency by 8 to 12 percent in the heavy trucks. All told, the tricks could save between 1.6 billion and 2.4 billion gallons of fuel per year, they estimate.
The focus was on trailers. While trucks already have fairings and other streamlining parts, little has been done to address drag on trailers, the researchers say.
Englar and colleagues developed pneumatic devices that blow air from slots at the rear of the trailers. The jets smooth the flow of air to eliminate bad things such as air-flow separation, vorticity and suction on the aft doors.
Other improvements include rounding aft trailer corners and installing fairings around wheels.
Englar said that lately he has received numerous inquiries from trucking companies large and small as well as from railroads.
The research has continued, using wind tunnels and drawing on studies of military jets done in the 1980s. The scientists also run real trucks for 45 miles at highway speeds on a test track to gauge fuel savings. Aerodynamic drag can be cut by up to 31 percent, they found.
"Aerodynamically, we have resolved unknowns raised in earlier testing, and the next step is to get this into a fleet of trucks for more extensive testing," Englar said. "At highway speeds, each one percent improvement in fuel economy would result in saving about 200 million gallons of fuel for the U.S. heavy truck fleet."
Englar still needs to figure out a more efficient air compressor setup to run the pneumatic system.
An interesting added benefit: The pneumatic system can also act like brakes.
"The pneumatic systems can turn a low-drag configuration into a high-drag configuration very rapidly, providing a lot more braking power," Englar said. "By turning the trailer into a non-moving pneumatic rudder, blowing can also restore directional stability should the truck be operating in destabilizing high side winds."