Aerodynamics is one of the most important elements when using formula-type vehicles in motorsport. Traditionally, estimating aerodynamic performance is mainly evaluated using a wind tunnel and steady-state simulation with a stationary vehicle. However, it is impossible to reproduce and estimate the flow field during cornering. For this reason, conducting aerodynamic simulation whilst considering the vehicle's motion can be effective. The unsteady aerodynamic forces acting on a formula car, including the vehicle's motion, were investigated using large eddy simulation. The study was based on a simplified formula car model. Two moving boundary methods, Arbitrary Lagrangian-Eulerian (ALE) method and non-inertial frame of reference method, were applied to the cornering simulation. To represent the change in aerodynamic forces around a formula car in its cornering motion, aerodynamic forces in quasi-steady simulations and that during cornering were compared. Finally, the effect of slip, yaw motion, and acceleration against the aerodynamic forces and center of pressure was investigated.
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In recent years, the dielectric barrier discharge plasma actuator (DBD-PA), which is a fluid control device, has been investigated for achieving both high aerodynamic performance and pleasing styling of transportation equipment. In this study, the authors installed a DBD-PA system on a simplified three-dimensional bluff automobile body to reduce the aerodynamic drag. In particular, the authors focused on the sides of the rear end of the body, where the local shape has high sensitivity regarding both styling and aerodynamic drag. At the rear sides of the automobile-like bluff body, a sharp edge rather than a smooth rounded corner often reduces the aerodynamic drag by promoting airflow separation. Therefore, the authors aimed to reduce the aerodynamic drag by using a DBD-PA system to promote flow separation at the rear end while retaining its rounded shape. Aerodynamic measurements using a one-fifth scale simplified automobile model were conducted in a wind tunnel. Preliminary investigation of the aerodynamic effect at the rear clarified how the longitudinal vortices from the rear pillar and the side edge of the trunk deck cause the drag increase at the rear-end corners. Two parallel DBD-PAs were installed on the rear surface to shift these vortices away from the corners by promoting flow separation. The drag reduction rate reached 3% at the highest applied voltage using the DBD-PA system on a rounded shape, and it achieved approximately half the effect of the sharp-edged shape. The longitudinal vortices were successfully kept away from the rear-end corners by the DBD-PAs. The surface pressure increased with the displacement of the vortices, which led to the drag reduction observed.
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