Aerodynamic Performance of Several Passive Vortex Generator Configurations on an Ahmed Body Subjected to Yaw Angles

We evaluate the aerodynamic performance of several passive vortex generators (VGs) placed on a standard Ahmed body, with a slant angle (α=35º), subjected to different yawing angles (β) using RANS based models. Rigorous validation of the numerical results is performed with previously published experimental data for (β≤8º) for the Ahmed body. Our model results depict a good overall agreement with several experimental data sets. An array of different vortex generators such as the delta-winglet (DVGs), the cylindrical (CVGs) and trapezoidal (TVGs) types are introduced on to the validated model. The introduction of CVGs and DVGs tend to have a beneficial aerodynamic performance for (β=0º). In contrast, the TVGs tends to impair the performance by producing massive flow separation over the slant for (β=0º). Conversely, for (β>0º), a swift transition happens with TVGs wherein, the high energy streamwise vortices that are produced tends to improve the pressure footprint and thereby reducing the overall drag. A deterioration in the performance of DVGs is predicted during (β>4º) wherein, the 'c'-pillar vortex on the leeward side interferes with the streamwise vortical structure which adversely influences the flow over the roof-slant edge. Overall, a maximum of ~8.5% and ~7.7% drag reduction appears to be possible with the designed CVGs and TVGs at smaller vehicle yawing conditions.