Separation Control by Streamwise Vortices in Flow around Automobile Front Bumper

Abstract

Separation control by plasma actuator is performed in flow around car front bumper to improve electric economy by reducing drag. The evaluation of flow separation control was performed using numerical simulation by OpenFOAM. A front bumper corner model was made in order to reproduce the actual model used in the wind tunnel experiments. Plasma actuator was installed in two different ways, common flow up type (CFU) and common flow down type (CFD) on the surface of front bumper corner model. The effect of separation control in PA both installations was analyzed in the distributions of streamwise velocity u in the various X-Y planes. The vorticity distribution in Y-Z plane showed the same tendency as the experimental results that the streamwise vortices created by the induced flow setting decreased as the flow downstream. From the results of Q-criterion, CFD case archived the development of streamwise vortices for the downstream direction, more than the case of in CFU. It provides insight into the understanding of the phenomenon of the separation control effect. In the evaluation using momentum thickness, CFD had the greatest separation control effect in the central area.