Influence of rear-roof spoiler on the aerodynamic performance of hatchback vehicle

See-Yuan Cheng,Shuhaimi Mansor,S.A Che Ghani,A Alias,W.A Wan Hamzah

doi:10.1051/matecconf/20179001027

See-Yuan Cheng, Shuhaimi Mansor + Show 3 more

Open Access

https://doi.org/10.1051/matecconf/20179001027

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Abstract

Rear-roof spoiler is commonly used for improving the aerodynamic performance of road vehicles. This study aims to investigate the effect of strip-type rear-roof spoiler on the aerodynamic performance of hatchback vehicles. The main parameter of study was the inclination angle of the spoiler. A computational fluid dynamics (CFD) method was used. The numerically obtained results were compared to the experimental data for validation of the CFD method. The spoiler effectively reduced the aerodynamic lift at positive inclination angle by causing the surface pressure near the roof-spoiler junction to increase. However, its effect is unfavourable when configured at negative angle due to the downward accelerating flow that causes the surface pressure around the roof-spoiler junction to drop. Although the aerodynamic lift was found to decrease with the spoiler angle, this was accompanied by drag increment.

Highlights

A properly designed rear spoiler can reduce the rear-axle lift of a vehicle
The spoilers are of inverted airfoil type and were mounted on the trunk of a simplified car model based on the HONDA S2000
The flow at the upper body separated near the trailing edge of the roof when without the spoiler, whereas, it separated near the end of the spoiler for all spoiler angles when a spoiler is used

Summary

Introduction

A properly designed rear spoiler can reduce the rear-axle lift of a vehicle. This effect is important because a vehicle with its rear-axle lift lower than the front exhibits better stability, i.e. requires minimum driver intervention to maintain a straight path [1]. The use of spoiler will enable a vehicle to achieve greater downforce (negative lift), and better traction without significant increase in its weight. There are two types of rear spoiler design: strips and free-standing wing. The effectiveness of wing-type spoiler has been reported in numerous studies. Tsai et al [2] investigated numerically five different spoiler configurations. All the cases had shown reduction in lift, only one out of five configurations succeeded in producing a negative lift coefficient value

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