Search Results

For open wheel race cars the front wheel flow and the interaction of its wake with downstream components is of significant importance. Considerable effort goes into the design of front wing end plates, barge boards and underfloor components in order to manage the front wheel flow. In this study a 50% scale Formula One front wheel assembly has been tested in the Durham University 2m₂ open jet wind tunnel to evaluate the effect of through-hub flow on its cooling drag and flow structures. Varying the amount of through-hub flow gave rise to a negative cooling drag trend whereby increasing the flow through the hub resulted in a decrease in drag. This observation has been explained both qualitatively and quantitatively by inlet spillage drag. Lower than optimum airflows through the brake scoop result in undesirable separation at the inside edge and hence, an increase in drag (reversing the cooling drag trend).

Detailed flow-field measurements in the wake of a 40 percent full-scale exposed wheel have been obtained using particle image velocimetry (PIV). Additional data have been acquired in the form of surface static pressure measurements acquired using the Durham University radio telemetry system. The results presented in this paper compare and contrast, both quantitatively and qualitatively, the physical differences that exist with respect to the flow structures of rotating and non-rotating wheels. Some of the ‘special’ features of the flow-field postulated by Fackrell, such as the ‘jetting’ phenomenon, have been revisited, examined and revised based on the surface static pressure and PIV data presented in this paper. The experimental observation of a flow mechanism is presented in terms of the rear jetting after the line of contact, and the effects of this have been considered and analyzed.

A radio telemetry system has been designed and developed at Durham University that enables surface pressure data to be transmitted from a rotating racing wheel to a host PC, where data post-processing is carried out. A multi-element wheel rim has been designed to allow the telemetry system to be located inside a pneumatic tire. Surface pressure distributions around the centerline of the wheel show good agreement with previous research. A flow field investigation has also been conducted, downstream of the wheel, for both stationary and rotating wheel cases. The results presented highlight some of the key features of the flow field and give confidence in the telemetry system.

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.