Method for Reducing Aerodynamic Drag on Tractor-Trailers
A bio-inspired sidewall design to increase fuel efficiency and lower greenhouse gas emissions.
Tractor-trailers are essential to the United States (U.S.) economy. The annual value of freight transported in the U.S. in 2017 was $19 trillion, an increase from $18 trillion in 2012. Of the $19 trillion, $13.7 trillion (72%) was transported by the trucking industry. The high fuel consumption by tractor-trailers (approximately 11,818 gallons of fuel per vehicle annually) can be largely attributed to their poor fuel economy (approximately 5.8 miles per gallon), which yields higher fuel costs and significant greenhouse gas emissions. Outside of engine losses, aerodynamic losses account for the largest fraction of fuel consumption for tractor-trailers. Several aerodynamic modifications to the body of the truck and the semi-trailer have yielded promising fuel efficiency results of anywhere from 5% to 10% efficiency increase. Current efforts to improve aerodynamic performance of tractor-trailers focus on optimizing tractor design and implementing drag-reducing trailer add-on structures such as skirts and fairings. However, there is currently no practical implementations of improved trailer sidewall or entire roof design.
Researchers at The Ohio State University, led Dr. Shaurya Prakash, have developed a series of novel wall body designs for semi-trailers that can be attached or integrated with the sidewalls or the roof of the trailers. The invention has three explicitly evaluated bio-inspired variations over the existing state-of-the-art planar configuration, which was used as a baseline comparison. The special geometry of the invention is effective in reducing aerodynamic drag by altering the airflow around the tractor-trailer such that the pressure incident upon the rear of the semi-trailer is increased. The advantages of this technology are reduced fuel costs and less frequent refueling for the operator of the tractor trailer. Wind tunnel experiments have proven that this technology reduces the drag coefficient by 12.9%, translating to an estimated savings of 1.6 – 2.3 billion gallons of diesel consumption annually for the entire United Sates trucking industry, given that more than 2.5 million heavy duty trucks are registered across the U.S. Lowering the drag coefficient by 12.9% for a full-scale class 8 tractor-trailer, as reported here, will be equivalent to approximately 6-8% in fuel savings. The inventors have completed computational proof-of-concept as well as a streamlined 6-foot physical prototype to show feasibility of making such a structure with in-lab processes. The prototype meets all design specifications and needs a manufacturing partner to scale-up.