What if you could reduce the drag of a tractor-trailer truck by 23% and therefore reduce fuel consumption by 11%? Further, what if the only modification to the trailer was to apply some decals and hook up an electric power source? According to Plasma Stream Technologies these savings are viable if the plasma flow control they are developing fulfills its promise.

Improve the Pressure Recovery Behind a Trailer using PlasmaGeometry courtesy of Nectar Design

Using ionized air (plasma) it is possible to control low speed flows (in fluid terms truck speeds are considered low speed). Using strategically placed anodes and cathodes (hence the need for electric power) to create the ionized air, it is then possible to control a larger movement of air via entrainment. Using flow control around the rear of a trailer is an obvious area to focus effort, as it is responsible for the majority of the drag from a tractor-trailer configuration.

Plasma flow control is not new, having already been proposed and tested as a non-mechanical method for aircraft control. Also the principle of creating ionized air was used in discredited (because they created ozone and were not that effective) air purifiers. Other means of active flow control, e.g., sucking or blowing, require ducts and pumps, whereas plasma generation is much simpler, only requiring solid state electrical systems.

Clear advantages of plasma flow control over passive (shaped-based) flow control is the relative ease of retro fitment of the anodes and cathodes to existing vehicles. If it really is just a case of applying decals, as claimed by Plasma Stream, then the fuel savings make this technology extremely attractive.