Kenworth: Advancing Aerodynamics, Fuel Economy By "Going with theAirflow"
KIRKLAND, Wash., November 12, 2001 - Nearly 20 years ago, Kenworth engineers went back to school. They went to the University of Washington and enrolled in a self-taught class called "Truck Aerodynamics". Led by the late Larry Orr, Kenworth's team of engineers used the university's wind tunnel to explore ways to improve airflow around heavy-duty trucks. The result was the 1985 introduction of the milestone Kenworth T600A model, which showed dramatic improvements in fuel economy over previous conventional trucks. Today, that wind tunnel is still used, but as a proving ground, not a laboratory. Instead, Kenworth has moved the wind tunnel lab to its company headquarters - putting a 'wind tunnel' inside its computers. "Kenworth uses Computational Fluid Dynamics (CFD) technology on the computer screen to see how truck design and product enhancements are affected by airflow," said Alec Wong, Kenworth senior project engineer. "Our continuing goal is to reduce drag so that our customers can realize even better fuel economy." Wong noted that Kenworth can do three things with its CFD analysis tool. "We can modify shapes to see how a redesign or modification affects the truck aerodynamics, identify areas of pressure loss, and visualize total airflow pattern," he said. Once an improvement is seen on the computer, a 20 percent scale model of the vehicle is made and undergoes traditional wind tunnel testing. If it proves out, a full-scale model is made for final validation. "Our three-step process saves our team a great amount of engineering time," Wong said. "It also allows us to bring improvements to market in a shorter amount of time." The CFD analysis tool has allowed Kenworth engineers to make incremental improvements that will be incorporated into its future production of its T2000, T800 and T600 models. "Customers won't notice the differences we'll make to the truck models, but they'll be there," Wong said. "For example, when the T2000 incorporates the latest design changes, it will have 2 to 3 percent less drag than previous T2000 models. "More subtle and not-so-subtle improvements are planned for the future," added Wong. "We're conducting CFD analysis on hoods, windshields, mirrors and other parts of the vehicle - such as the underbody and underhood airflow, wheel wells, and gap between the tractor and trailer. Each individual improvement might be small - affecting fuel economy by a half-percent here and half-percent there - but these changes all add up and our customers will benefit." The CFD tool also has enabled Kenworth design engineers to fine-tune the aerodynamics of the HVAC system inside the cab. "This accomplishes two things. First, the driver is more comfortable due to controlled airflow," Wong said. "Second, by making the airflow distribution more uniform inside the cab, the HVAC system doesn't have to cycle on as frequently. This means that less power needs to come from the engine and, ultimately, that translates into better fuel economy." # Kenworth Aerodynamics Sidebar: Kenworth Engineers Give Customers Feedback On Aerodynamics According to Steve Gilligan, Kenworth general marketing manager, Kenworth has always strived to make aerodynamics as stylish as possible. "But we're also realists," Gilligan said. "Some of our customers like to showcase chrome air cleaners and big stacks. Others want exposed fuel tanks. There's definitely a tradeoff when it comes to aerodynamics." How much tradeoff? "Our CFD and wind tunnel verification programs help us provide answers to customers," Gilligan said. "If they want to spec a chrome air cleaner -- and want to know the impact on that decision -- we have that information. We can show them, for example, that exhaust stacks may penalize their fuel economy by about 1 percent," he said. "Or, if they want to know the impact of a full aerodynamic fairing package, we can show data that indicates there can be a 20 percent improvement in the drag co-efficient, which translates to a potential 10 percent improvement in fuel economy. "Bottomline," Gilligan said, "when spec'ing a Kenworth, we can help our customers make intelligent choices between style and aerodynamics." Kenworth Truck Company, a division of PACCAR Inc, is a leading manufacturer of heavy and medium duty trucks. Kenworth's Internet home page is at www.kenworth.com. # NOTE TO EDITORS: If you would like high-resolution versions of the attached low-res images, please reply to this email.