van den Berg, Martinus Anthoon
Aerodynamic interaction of an inverted wing with a rotating wheel
University of Southampton, School of Engineering Sciences,
This research contributes to the knowledge on aerodynamic wing - wheel interaction. Hereto an experimental and computational study has been performed, during which the wing ride height and the wing - wheel overlap and gap have been considered as the primary variables. The wheel drag for the combined configuration is generally lower at low ride heights and higher at high ride heights compared to the case without wing. This results primarily from changes in the flow separation over the top of the wheel - partly induced by the wing circulation - from the channel flow along the inside of the wheel and from the vortex interaction in the wheel wake. The wing downforce increases at low ride heights due to the wheel presence, but reduces at high ride heights. The modified channeling effect, vortex and separation effects govern the wing flow field, although the wheel circulation acts as an additional mechanism for downforce enhancement and limitation.
The wing - wheel interaction has been studied extensively for a baseline configuration, using forces, on-surfaces pressures for the wing and wheel, oil flow and PIV data. A reduced set of data has been obtained for alternative overlap and gap settings. An increase in overlap generally leads to a reduction in wheel drag and wing downforce. A larger gap setting has relatively little influence on the wheel drag at low ride heights, but shifts the higher ride height part of the curve to lower values. The wing downforce is generally slightly lower when the gap increases. An analogy between the wing - wheel configuration and a multi-element airfoil has been used to partly explain the aerodynamic interaction between the components, based on the cross flow along the flap trailing edge.
The application of a steady RANS computational approach with Spalart Allmaras turbulence model has been assessed for a baseline configuration over a range of ride heights. Qualitatively, the flow field is predicted fairly accurately, but the flow quantities correlate less satisfactory with the experiments. The downstream interaction in underpredicted, resulting in lower values for the wheel drag, in particular at high ride heights. The use of non-conformal zones around the wing is one of the causes for this discrepancy.
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