Tire Deformation Modelling for High-Speed Open-Wheel Aerodynamic Investigations

This article introduces a finite element (FE) approach to determine tire deformation and its effect on open-wheel race car aerodynamics at high vehicle velocities. In recent literature tire deformation was measured optically. Combined loads like accelerating at a corner exit are difficult to reproduce in wind tunnels and require several optical devices to measure the tire deformation. In contrast, an FE approach is capable of determining the tire deformation in combined load states accurately. Additionally, the temperature influence on tire deformation is investigated. The FE tire model was validated using three-dimensional (3D) scan measurements; stiffness measurements in the vertical, lateral, and longitudinal direction; and the change of loaded radius with speed at different loads, respectively. The deformed shape of the tire of the FE model was used in a computational fluid dynamics (CFD) simulation. The influence of these tire deformations was investigated in a CFD study using a full-vehicle model. The CFD model was validated through a vehicle dynamics model. Finally, three maneuvers characteristic of race cars were simulated. A straight-line braking (SLB), end of straight driving (EOSD), and high-speed cornering (HSC) maneuver based on a vehicle dynamics simulation were simulated using this combined approach of FE and CFD. The tire deformation included proper wheel load, car speed, wheel speed, camber angle, and slip angle for each wheel. The CFD full-vehicle model took chassis slip angle, body roll angle, and wheel steering angle into account in order to match the real driving situation. The results show that realistic tire deformations provide better insight into the effect of rotating wheels on the aerodynamics of full vehicles, especially the flow region behind the tires of race cars.