Aerodynamics of a convex bump on a ground-effect diffuser

Date published

2018-04-19

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Publisher

Journal of Fluids Engineering

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Article

ISSN

0098-2202

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Citation

Ehirim OH, Knowles K, Saddington AJ, Finnis MV. (2018) Aerodynamics of a convex bump on a ground-effect diffuser. Journal of Fluids Engineering, Volume 140, Issue 9, 19 April 2018, Article number 091102; Paper No: FE-17-1625

Abstract

A ground-effect diffuser is an upward-sloping section of the underbody of a racing car that enhances aerodynamic performance by increasing the downforce, thus improving tire grip. The downforce generated by a diffuser can be increased by geometric modifications that facilitate passive flow control. Here we modified a bluff body equipped with a 17° diffuser ramp surface (the baseline/plane diffuser) to introduce a convex bump near the end of the ramp surface. The flow features, force and surface pressure measurements determined in wind-tunnel experiments agreed with previous studies but the bump favorably altered the overall diffuser pressure recovery curve by increasing the flow velocity near the diffuser exit. This resulted in a static pressure drop near the diffuser exit followed by an increase to freestream static pressure, thus increasing the downforce across most of the ride heights we tested. We observed a maximum 4.9% increase in downforce when the modified diffuser was compared to the plane diffuser. The downforce increment declined as the ride height was gradually reduced to the low-downforce diffuser flow regime.

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Github

Keywords

aerodynamics, ground-effect diffuser, convex-surface, pressure-recovery, downforce

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Attribution 4.0 International

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