November 1, 2008 Engineers made aerodynamic alterations to the design of truck trailers in order to reduce drag and improve fuel economy. The design uses pressurized air active flow control techniques along with conventional aerodynamic streamlining. If installed throughout the U.S. trucking fleet, these technologies for reducing aerodynamic drag could improve fuel economy by eight to twelve percent.
- Automotive and Transportation
- Fossil Fuels
- Transportation Science
- Alternative Fuels
- Energy conservation
- Automobile emissions control
- Common ethanol fuel mixtures
- Automotive aerodynamics
With gas prices spiking over $4 in 2008, Americans are spending more than ever to fill up the tank. Truckers alone have seen the cost of a fill-up jump 116 percent in the last five years. That can add up to higher costs for anything that gets to you in an 18-wheeler, from food to furniture. Thanks to recent research, science may have found the answer to the problem.
Imagine spending over $1,000 dollars just to fill your gas tank. For trucker Ray Wall, it's a harsh reality.
"I think we used to fill it up for $500, and it's over a grand now," Wall said.
With tanks that hold up to 200 gallons and diesel prices spiking over $5, Kenneth Lopez says he's feeling the pinch on every trip.
"Three years ago, $100 gave me 37 to 40 gallons," said Lopez. "Now, $100 can barely give me 15. It's ridiculous."
Trucking accounts for 19 percent of our overall fuel consumption. That translates into 39 billion gallons of diesel each year, and it doesn't help that big rigs get just five to seven miles per gallon. One big reason is drag. At highway speeds, airflow across the square edges on the back of a tractor trailer creates a vortex that works against forward motion. That vortex burns fuel.
"The more drag that a tractor trailer has, the lower miles per gallon it's going to get," said Robert Englar, M.S.A.E., a research engineer at the Georgia Tech Research Institute in Atlanta, Ga. "If I can improve the drag coefficient of a tractor trailer, I can increase its fuel efficiency or make it get more miles per gallon."
Using aerodynamic technology, engineers at the Georgia Tech Research Institute found a way to adapt truck design to increase fuel efficiency. By retrofitting the back with small rounded panels and using a system that blows compressed air to redirect airflow over the back of the trailer, they reduced drag by up to 32 percent on actual test vehicles.
"We could increase the fuel economy of the test tractor trailer by between 11 and 12 percent," Englar said.
If applied to the country's entire 18-wheel trucking fleet, that adds up to savings of 2.4 billion gallons of diesel a year. This research, sponsored by the United States Department of Energy, could one day help lower the cost of products, reduce our dependence on foreign oil and keep big rigs rolling.
STREAMLINING MAKES A BIG DIFFERENCE: Air resistance is a huge problem for automotive engineers. This is especially true for the trucking industry. With enormous vehicles hauling enormous loads, aerodynamics issues have long taken a back seat in design. Now, with concerns over fuel prices and environmental impacts increasing, engineers are attempting to tweak truck cabs and trailers in hopes of reducing the air resistance and, consequently, the amount of fuel consumed.
MPG COMPARISONS: When traveling the same distance, what would save more fuel ý improving fuel efficiency of Vehicle A from 8 miles per gallon to 10, or improving the fuel efficiency of a Vehicle B from 25 mpg to 50? Surprisingly, the answer is that the Vehicle A saves more gas. Over the course of 100 miles, the Vehicle A uses 12.5 gallons of gas at 8 mpg, and 10 gallons at 10 mpg, a savings of 2.5 gallons. Vehicle B would use 4 gallons of gas at 25 mpg, and 2 gallons of gas at 50 mpg, a savings of 2 gallons. Although driving a vehicle that uses the least gas is the optimum situation in terms of the emissions and the cost, this example highlights the way small improvements in mileage can add up to savings for the trucking industry.