Aerodynamic Drag Reduction Investigation for a Simplified Road Vehicle Using Plasma Flow Control

Abstract

The effect of plasma flow control on reducing aerodynamic drag for ground vehicles is investigated. The experiments were carried out for a simplified ground vehicle using single dielectric barrier discharge (SDBD) plasma actuators. The plasma actuators were designed to alter the flow structure in the wake region behind the vehicle. The Ahmed body was modified to allow eight different vehicle geometries (with backlight or slant angles of 0° and 35°). Each of these were further modified by rounding the edges with different radii. Flow visualizations such as particle streams and surface oil were used to quantify features of the local flow field. The drag on the models was measured using a force balance as well as by integrating the mean velocity profiles in the model wakes. The results indicated that flow modifications needed to be applied symmetrically (upper to lower and/or side to side). This was demonstrated with the 0° backlight angle (square-back) that had all four side-corners rounded. Plasma actuators were applied to all four of the rounded edges to enhance the ability to direct the flow into the wake. Wake measurements showed that steady actuation at a fixed actuator voltage reduced the drag by an average of 20% at the lower velocities (below 15 m/s) and by 3% at the highest velocity tested (20 m/s). Model constraints prevented increasing the plasma actuator voltage that was needed to maintain the higher drag reduction observed at the lower speeds.