Development and performance evaluation of undertray diffusers during racing manuevers
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Typ
Examensarbete på kandidatnivå
Program
Publicerad
2021
Författare
de Wilde, Willem
Gunnarsson, Jacob
Ivarsson, Lena
Karlsson, Linnéus
Kolte, Oskar
Olander, Daniel
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
A potential to develop the monocoque and diffuser on the Chalmers Formula Student
(CFS) car, as to increase its downforce, was identified by CFS. Downforce is
the downward aerodynamic lifting force that is obtained when a pressure difference
is created between the top and bottom of the car. This effect is crucial for the grip
of the car in driving scenarios like cornering, accelerating and braking. With more
downforce, accelerating and braking can be done faster, and higher speeds can be
maintained in cornering.
The objective of this project is to develop a methodology for modeling of aerodynamic
forces during different racing maneuvers of a CFS car. These new methods
are purely computational. Further, the methods are used in the development of a
new diffuser concept. This is done with the aim of providing CFS with knowledge
and proof-of-concept of the implementation of a new diffuser, which could increase
aerodynamic performance of the car.
It was shown that straight ahead driving, braking, and cornering were the most
critical driving scenarios. These were used to perform three types of simulations.
Different diffuser designs were simulated based on these scenarios. It was further
shown that the following parameters had an effect on aerodynamic performance: the
expansion angle of the diffuser, the starting point of the diffuser, the radius of the
diffuser throat, and the implementation of strakes and side floors. Differences in the
performance robustness of the different designs were observed.
Two diffusers provided the greatest downforce: one with a 13° expansion angle
and the other with a 19° expansion angle. The diffusers were in other regards identical.
Lastly, the 13° diffuser was chosen as the best contending design, due to its
robust performance in each of the simulated driving scenarios.
Beskrivning
Ämne/nyckelord
CFD , aerodynamics , Formula Student , downforce , lift coefficient , drag coefficient , diffuser , racing manuevers , cornering , braking