Experimental study of yaw angle effect on aerodynamic performance of road vehicle with rear spoiler

• Main Author: Chin, Kwang Yhee
• Format: Thesis
• Language: English; English
• Published: 2021
• Subjects: T Technology (General); TL Motor vehicles. Aeronautics. Astronautics
• Online Access: http://eprints.utem.edu.my/id/eprint/25981/; https://plh.utem.edu.my/cgi-bin/koha/opac-detail.pl?biblionumber=121061

A spoiler is an external structure added to the trailing edge of the roof of a vehicle to increase the downward force, and hence, improves its traction. To date, the performance of spoilers had mainly been optimized for the straight-ahead driving condition. However, during cornering, good traction is critical to ensure that sufficient centripetal force is generated for the vehicle (o drive through the curve without slip. Hence, this research aims to investigate the effects of yaw angle change corresponding to cornering on the flow characteristics of various typical spoiler configurations, and the subsequent influence on the aerodynamic performance of vehicles. The vehicle type tested is the hatchback vehicle while the rear spoiler configuration employed are those typically found in real-life applications, namely, strip type, standing wing type, and the combination of the strip and wing (i.e. combo type). Ahmed model which had been scaled down to 75% of the original model was adopted to simulate the idealized hatchback type vehicle. The rear spoilers are being mounted on the roof end of the vehicle model. The experimentations are conducted in a low-speed wind tunnel at the Reynolds number of 2.7 x 106. The yaw angle tested ranges from 0° to 14°, at 4° increment. At zero yaw angle, the C1 of the vehicle model fitted with either of the three spoiler types is lower as compared to the vehicle model without a rear spoiler. Although the Srip-type spoiler provides the same advantage when comes to the Cd. performance, however, the Wing-type and Combo-type spoilers show an increase in Cd. Under the influence of the yaw angle, both the Cd and C1 of the vehicle model increase disregard the use of the rear spoiler. When without a spoiler, there exists a critical yaw angle value where the Cd and C1 of the vehicle model will surge by as much as 29% and 91%, respectively. However, the application of the three spoiler types could prevent such an undesirable tendency. In addition, at low yaw angle range, the vehicle model fitted with the strip-type spoiler shows a reduction in Cd, whereas the cases fitted with the wing-type and combo-type spoilers show a higher Cd. However, all the cases fitted with a spoiler produce a lower C1 as compared to the without spoilers case. Overall, the use of the of the rear spoilers could improve the driving stability and safety of the vehicle. However, the wing type and combo type could cause an increase in the aerodynamic drag of the vehicle operated at zero yaw angle or low yaw angle range.