Experimental and computational study of the flow around a stationary and rotating isolated wheel and the influence of a moving ground plane

This study investigates the aerodynamic behavior of the flow around a rotating and stationary 60% scale isolated wheel, with and without the use of a moving ground plane. The aim of this research was to improve the understanding of the fundamental aerodynamic flow features around a wheel and to examine how rotation and moving ground planes modify these and affect the production of drag. A bespoke rotating wheel rig was designed and wind tunnel tests were performed over a range of pre to post critical Reynolds numbers. Force coefficients were obtained using balance measurements and flow field data were obtained using Particle Image Velocimetry (PIV). The unsteady flow field data generated was used to validate unsteady CFD predictions. These were performed using STARCCM+ and a k- SST Improved Delayed Detached Eddy Simulation (IDDES) turbulence model. This was seen to outperform other models by capturing an increased amount of finer detailed, high frequency vortical structures. The CFD showed good agreement with the experimental results providing, for the first time, a validated numerical methodology. Comparing stationary and rotating wheels the CFD and experimental data both illustrated large scale structural differences in the surrounding flow due to changes in separation and wake structure. The rotating model also exhibited a lower drag at post critical Reynolds numbers, which is corroborated by existing literature. Importantly, the CFD showed minimal difference between a stationary and moving ground plane simulation with a rotating wheel. This is evidence that, provided the wheel is rotating, valid experiments can be performed without the complexity of a moving ground plan