The Eco Flaps aerodynamic splash guards were recently evaluated for fuel savings on less than truckload equipment in multi-trailer setups.

The tests were completed by Exa Corporation in late 2017, performing an aerodynamics and fuel economy analysis through computational fluid dynamics simulations on a day cab tractor with two 28-foot trailers connected by a dolly. It found an estimated 2.7% fuel savings based on the reduction in drag.

"The segment of the trucking industry that run with two or three trailers at a time, which includes most LTL carriers, is really limited when it comes to aerodynamic devices. Most are designed specifically for single-trailer application," said Bren Marshell, vice president of sales for Eco Flaps. "Our recent work with Exa Corporation shows that when Eco Flaps are installed in all flap positions on multiple trailers, drag is reduced significantly, resulting in greater fuel savings and quick ROI."

Exa Corporation created four different scenarios: a baseline with conventional flaps; changing out the truck and dolly flaps for Eco Flaps; a full swap out of all eight flaps for Eco Flaps; and an equipment setup with no flaps used. The results showed a 4.7% improvement in drag at highway speeds when all eight flaps were removed - even though the pup trailers already using aerodynamic skirts. The use of eight Eco Flaps - a full swap out - created the same results.

"The Exa Corporation simulations showed a major impact when equipping the dolly flaps in addition with the tractor and trailers," said Marshell. "Not including the dolly greatly restricts the airflow and thereby significantly reduces fuel savings from the leading trailers."