Experimental Study of Wheel-Vehicle Aerodynamic Interactions

Abstract : The thesis aims to provide a better understanding of the wheel-vehicle interaction, via experimental investigations on a 2/5-th scale vehicle with an underbody diffuser and 2/5-th scale wheels equipped with Michelin tires. The vehicle geometry, based on ASMO model, was modified prior to the PhD work, in order to achieve a reasonable front wheel yaw angle, and a realistic wake balance with four rotating wheels. It is the baseline configuration in the scope of this work.The findings demonstrate that the well-balanced wake of the baseline configuration can be easily modified by different wheel states or tire modifications, especially at the rear axle. This results from a global effect of the underbody momentum modifications, i.e. a high wake sensitivity to the underbody flow. On the contrary, when the vehicle mean wake develops into a non-balanced topology, it is more robust towards underbody perturbations such as different wheel states or tire modifications. By eliminating four wheels or front wheels, the underbody momentum flux is vastly increased; by eliminating the underbody diffuser, which is a vehicle geometry modification, the underbody momentum flux is significantly reduced. In these two circumstances, one can observea robust downwash from the roof, independent of the wheel states or tire modifications. Besides, there is a more local effect of the wheels near wakes on the aerodynamic lift and drag of the vehicle. Low pressure regions in the underbody downstream the front wheels have an effect on vehicle lift. The rear wheels impose pressure conditions on the vehicle base, influencing the vehicle drag. Particularly, the merging of nonclosed mean wakes of the rear wheels with the vehicle wake can give rise to strong penalty in vehicle drag.
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Theses
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Submitted on : Monday, June 17, 2019 - 5:21:52 PM
Last modification on : Friday, November 8, 2019 - 3:05:30 AM

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Yifei Wang. Experimental Study of Wheel-Vehicle Aerodynamic Interactions. Other. ISAE-ENSMA Ecole Nationale Supérieure de Mécanique et d'Aérotechique - Poitiers, 2019. English. ⟨NNT : 2019ESMA0002⟩. ⟨tel-02157958v2⟩

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