Affiliation:
1. Cranfield University, Advanced Vehicle Engineering Centre
2. Cranfield University, Centre for Computational Engineering
Abstract
<div class="section abstract"><div class="htmlview paragraph">Racing and high-performance vehicles utilize their underbody floor and diffuser
as efficient mechanisms to generate the majority of their downforce. Previous
work has primarily been focused on simplified bluff bodies with plane diffusers.
The little published work on more complex multichannel diffusers has shown
improved downforce generation over plane diffuser, but with limited
understanding of the flow features and their response to ride height. This study
analyses the performance and complex flow features of a high-performance vehicle
equipped with a multichannel diffuser at various ride heights. A comparative
assessment between RANS and DDES simulations is performed, which shows that both
models adequately predict downforce and underbody flow features at high to
medium ride heights, but only the DDES model is able to capture the unsteady
flow behavior, which dominates the diffuser at low ride heights. Subsequently,
an in-depth aerodynamic analysis of the vehicle’s ride height dependency is
conducted using the DDES simulations. The analysis shows the crucial role of the
diffuser’s side plate vortices on the flow entertainment and formation of
vortices at the separators. Moreover, the analysis describes the influence of
ride height on the strength and stability of the vortex flow in the diffuser.
Findings at very low ride heights demonstrate that strong interaction between
the vortices and flow along the ground plane cause the formation of relatively
unstable vortices, which provide less flow entertainment and thereby cause a
reduction in downforce.</div></div>
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