Härtill 4 uppsatser

Diss. (sammanfattning) Göteborg : Chalmers tekniska högskola, 2023

Many factors are pushing automotive manufacturers to increase the efficiency of their fleets; some of these are legislative (requiring reduced greenhouse gas emissions) as well as ensuring sufficient range and power consumption in electric vehicles. An important part of improving the energy efficiency of road vehicles is reducing their aerodynamic drag. Much effort has gone into improving the aerodynamics of trucks, cars, and buses. There are, however, limits on the attainable aerodynamic performance due to several different factors. This thesis focuses on a relatively unutilized way of reducing the aerodynamic drag of vehicles, that is, vehicles driving in close proximity, or platooning. Although such a solution has long been envisioned as a way of reducing drag, it is only now becoming possible with advancements in vehicle automation and communication. Platooning is, however, regularly, and successfully used in many sports. Although there have been many studies on the topic, the focus has mostly been on the differences in drag. This thesis attempts to improve the understanding of the observed changes in drag for a cab over engine style tractor-trailer, a passenger car, and a coach bus. The work herein was performed using both CFD simulations and wind tunnel experiments. The aerodynamics of platoons were investigated for separation distances between 0.5m and 30m, 0m and 0.5m lateral offsets, and 0°, 5°, and 10° yaw angles, to emulate wind conditions. The effects for different vehicle types are generally similar, although with varying magnitudes depending on the combination.