As is well known, the dynamic and acoustic characteristics of vehicles change under the influence of oncoming flows of air. The more streamlined the shape of a car, the less the onrushing air flows affect its speed and its economy.
Scientists at the University of Florida have proposed using small electronic devices that generate charged particles to optimise aerodynamic parameters.
The working principle of such devices is the formation of a plasma, an ionised gas made up of electrons and ions. For this, electrodes are placed on the surface of the car in an asymmetric and uneven pattern. By controlling the parameters of such a system one can bring it about that the air flows move in a particular direction.
The devices are called plasma actuators. They help to reduce the force of air resistance and, as a consequence, lower the level of noise, thereby increasing the power of the vehicle.
The device consists of two metal plates (electrodes) separated by a dielectric. When a voltage is applied, a dielectric barrier discharge forms. A space charge arises at the edges of the exposed electrode, and the electric field acts on it. The electric charges set in motion in this way create a certain flow structure: in a medium at rest this is a vortex.
Classical design methods of reducing air resistance exist today, the use of stabilisers, flaps and the shape of the fuselage for example. Unlike these, plasma actuators can be used only when they are needed, during a climb for example.
In the experiments that were carried out, flows of smoke lit by a laser were directed onto an aerodynamic surface. It was established that the use of actuators helps to control the movement of air flows in space, and changing the configuration of the system allowed them to form laminar and turbulent zones on the surface.
Today the question of using plasma actuators for flow control is a live topic all over the world. This is because the low production cost makes the idea of introducing this development very attractive in the design of aircraft first of all, and of other vehicles as well.