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Characterisation of the tyre spray ejected downstream of a bluff automotive body

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conference contribution
posted on 2022-07-01, 10:41 authored by Conor Crickmore, Andrew GarmoryAndrew Garmory, Daniel ButcherDaniel Butcher
Considerations of surface contamination and airborne spray are becoming increasingly significant throughout the automotive design process. Advanced driver assistance systems, such as autonomous cruise control, are growing in popularity. These systems rely on external sensors, the performance of which may be impaired by both direct obstruction and spray. Existing experimental methods of assessing front-end surface contamination and wiper performance have typically utilised fixed spray-grids positioned upstream of the vehicle. The resulting spray is largely steady in nature, in contrast to the unsteady flow-field and tyre spray that would be produced by preceding vehicles. This paper presents the numerical analysis of the spray ejected downstream of a simplified automotive body. The continuous phase (air) is solved using a DDES-based approach coupled with a Lagrangian representation of the dispersed phase (water). Two configurations are examined, a square-back configuration, and a variation employing 20° rear-end side tapers. The inclusion of side tapering results in a significant change in wake topology and the resulting spray cloud. Good agreement is achieved between initial single-phase predictions of the continuous phase and existing experimental data. The spray cloud of both configurations is found to be highly unsteady, driven by vortical structures in the near- and far-wake, and is altered significantly by what are relatively minor changes to the geometry. Proper Orthogonal Decomposition reveals comparable spatial modes in the mass flux field of the dispersed phase and the continuous phase velocity field downstream of the vehicle. However, the correlation between the temporal coefficients of these modes is relatively weak. This highlights the presence of slip effects between the two phases, coming as a result of particle inertia, and the need to consider both phases simultaneously in future studies of spray dynamics.

Funding

Engineering and Physical Sciences Research Council (EPSRC)

Proposal for a Tier 2 Centre - HPC Midlands Plus

Engineering and Physical Sciences Research Council

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History

School

  • Aeronautical, Automotive, Chemical and Materials Engineering

Department

  • Aeronautical and Automotive Engineering

Published in

SAE Technical Papers

Issue

2022

Source

SAE World Congress Experience

Publisher

SAE International

Version

  • AM (Accepted Manuscript)

Rights holder

© SAE International

Publisher statement

This paper was accepted for publication in the journal SAE Technical Papers and the definitive published version is available at https://doi.org/10.4271/2022-01-0893

Acceptance date

2022-01-05

Publication date

2022-03-29

Copyright date

2022

ISSN

0148-7191

eISSN

2688-3627

Language

  • en

Location

Detroit, Michigan, USA

Event dates

5th April 2022 - 7th April 2022

Depositor

Dr Andrew Garmory. Deposit date: 30 June 2022

Article number

2022-01-0893

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