Increasing fuel savings of Class-8 tractor-trailers by reducing aerodynamic drag

Class-8 tractor-trailers consume about 75% of the total fuel used by trucks which, combined with Class-7 tractor-trailers, equates to 11.3% of total oil. This high of fuel usage presents an economic problem for companies, an environmental concern as CO₂ emissions are released, a societal issue as these tractor-trailers transports all sorts of goods, and a technical challenge for improvement of its fuel efficiency. Reducing aerodynamic drag, therefore, increases fuel savings and reduces CO₂ emissions. For example, a 10% reduction of drag results in a 6% savings in fuel that equates to a decrease of 10,764 pounds of CO₂ emissions per tractor-trailer per year. Aerodynamic drag is the sum of pressure and skin friction drag. Although aerodynamic studies suggest that surface modifications and gap coverage (between the truck and trailer) can lead to the reduction of aerodynamic drag on Class-8 tractor-trailers, no existing commercial technologies presently exist. Existing technologies, such as side skirts and trailer tails, are primarily aimed at reducing pressure drag. This paper presents the application of a rigorous design process to develop novel drag reduction concepts focused on reducing skin friction drag and pressure drag while focusing on surface concepts and gap region concepts. Metrics of concept evaluation are also based on environmental impacts, manufacturability, maintainability, reliability, usage and disposal, and cost effectiveness.