Racing Car Wheel Aerodynamics – Comparisons between Experimental and CFD Derived Flow-Field Data

Detailed flow-field data have been acquired using experimental and computational techniques in the wake of a 40% full-scale exposed wheel. The experimental investigation focused on taking discrete single-point measurements in the wake using a pneumatic 5-hole pressure probe. A wake integral method was used to compute the total drag force acting on the wheel.

The computational aspects of the investigation used the commercially available Fluent 6.0 CFD package. A tetrahedral volume mesh was used to discretise the flow domain and the k-ε turbulence model was used for all calculations. The boundary conditions were set according to the experiment.

As the tire rotates the work done on its surface shear layer leads to increased velocities and compression immediately ahead of the contact patch which results in pressure coefficients in excess of unity. This leads to an outflow from this high pressure zone; an effect that is known as jetting. The reverse effect occurs behind the contact patch. The front and rear jetting phenomena were successfully predicted using the computational model, which corroborated well with other experimental data obtained by the authors.