With gas prices fluctuating and the oil supply decreasing, engineers are working on ways to make large trucks more fuel-efficient.
What does that mean for the average person? With large truck usage accounting for 19 percent of the overall fuel consumption, this translates into 39 billion gallons of diesel each year needed. Numbers like this really dig into the fuel supply.
So engineers are looking at ways to make trucks more aerodynamic so that they have less drag and therefore better gas mileage. To date, engineers at the Georgia Tech Research Institute have discovered that retrofitting the back of the truck cab with small rounded panels and using a system that blows compressed air to redirect airflow over the back of the trailer, can reduce drag by up to 32 percent and fuel economy by 11 to 12 percent. This adds up to savings of 2.4 billion gallons of diesel a year.
With numbers like this, the U.S. Department of Energy has been behind the project and has been so since the late 1990s. Initial tests used simple scale model tractor-trailers in a GTRI’s low-speed wind tunnel. Results seemed good until full-scale trucks were used and this is when the results fell short of expectations. Researchers then went back to their wind tunnel with another truck design.
After rolling edges on the body of the truck’s trailer along with a few other modifications, tractor-trailers were tested again by running them through several different 45-mile runs around a 7.5-mile oval at highway speeds of 65 and 75 miles per hour. To make sure the modifications worked, a control truck that did not have the aerodynamic improvements or pneumatic control system as a modified truck was operated under the same conditions. Comparisons were made and sure enough, the engineering worked.
Another added benefit discovered during testing was that the differential blowing unit improved control of trailers in crosswinds by helping compensate for the wind direction.
So why isn’t every new large truck being made modified with the new design? Before the new pneumatic control system can be widely used, researchers will have to choose the best source of compressed air for the blowing system. Options include a diesel-powered motor installed in the trailer like current refrigeration units, bleeding pressurized air from the truck’s supercharger, or a simple chain drive to turn air blowers from the trailer’s wheels. Aerodynamic drag becomes dominant only at higher speeds, so the blowing would be turned off when the trucks were idling or operating at low speeds.
The addition of air blowers will require more power, therefore, researchers have to balance out the units additional pull with the savings. The final issue researchers are testing is the protection of the pneumatic surfaces from damage during docking.
Once researchers have finalized their studies, we may see a whole new fleet of big trucks on the road that get more miles per gallon, a reduction in carbon emissions and are more easily controlled when it is windy.