Abstract
dc:description.abstractAn investigation has been conducted to study the flow around a deformed pneumatic tyre. An experimental rig is presented which enables an isolated tyre with Formula One inspired wheel geometry to be towed through a water towing tank at variable axle height, camber and yaw, with a highly accurate ground condition. This uses a PIV set-up with cameras under a glass floor to give high resolution 3D velocity field data around the lower surfaces of the tyre and throughout the downstream wake. Data are presented showing a detailed view of the formation process of vortices generated on the front and rear surfaces of the tyre near the ground, and their downstream behaviour. This data informs discussion of an updated model of the vortex lines around the lower half of the tyre. Using a new post-processing method, vortex structures in instantaneous flow fields have been identified. The unsteadiness of the downstream flow is shown through a number of individual runs, with key flow states characterised. These states are linked to unsteady behaviour in the vortex formation process. Using the experimental rig, the tyre has been deformed with varying vertical loading, camber angle and yaw angle, as a Formula One tyre would experience in a race. These deformations have been shown to influence the time-averaged and instantaneous flow field. Cambering a tyre is shown to bias the downstream vortex system to the side leant towards. This is a result of the instantaneous data more frequently favouring that side, with high instability still present. Vertical deformation is shown to increase the time-averaged strength of both downstream vortices by modifying the ground vortex formation in a similar way to cambering. Finally, a yawed tyre is investigated. The yawed wake is shown to be highly asymmetric, but much more stable in time. The yawed near wake is shown to be dominated by a ground vortex on the leeward side, generated through asymmetry in the vortex formation process. These results show the importance in aerodynamic car design of simulating accurate tyre geometry at the ground and consideration of both the instantaneous flow behaviour and varying tyre geometry.
Degree
thesis:*- Name dc:type.qualificationname
- Doctor of Philosophy (PhD)
- Level dc:type.qualificationlevel
- Doctoral
- Grantor dc:publisher.institution
- University of Cambridge
- Year dc:date.issued
- 2020
Author and committee
dc:creator, dc:contributor.*- Author dc:creator
-
- Parfett, Alex
- Advisors dc:contributor.advisor
-
- Babinsky, Holger
- Harvey, John
Subjects
dc:subject × 5Rights
dc:rightsIdentifiers
dc:identifier.*- Author Identifier
- 0000-0002-7647-7126
- OAI identifier oai:identifier
- oai:www.repository.cam.ac.uk:1810/317000