Drag Behavior of 25° Ahmed Body Effect by Deflector Length and Angles

This study investigates the influence of deflector length on the aerodynamic drag and flow characteristics of a standard 25 degrees Ahmed body by a numerical approach. Two class of deflector was selected for investigation to elucidate the impact of angles parameter on both drag and flow characteristics. The first class has a fixed length of 9% of the slant's length and spanning angles from -25 degrees to 25 degrees. The second one has length varying from 0% to 100% of the slant's length deflectors and angles from -5 degrees to 5 degrees. Reynolds Average Navier-Stokes equations with the generalized k-omega (GEKO) model were selected. The numerical methods were conducted with the help of Ansys Fluent software. The numerical parameters of the model were adjusted to obtain the satisfying results of flow and drag. Numerical results were verified by experimental data at similar flow conditions. It was shown that the -5 degrees defector allows for a reduction drag for all lengths tested with a maximum reducing drag of 19%. At the 5 degrees deflector, 14% of the drag reduction was observed when its length is 0.3 length of the slant. For longer deflector lengths, the drag increases again. The deflector shows a good passive technique for drag reduction. However, parameters of the deflector should be carefully investigated and selected. The detailed skin-friction structure, pressure distribution, and wake flow fields relating to the drag behavior are analyzed in this study.