This project developed a study on methods to increase downforce on the university’s Formula SAE vehicle by implementing a lightweight, efficient aerodynamic design. The team planned to improve the performance and reduce lap times of the vehicle with an undertray, which grants better wheel traction and stability while handling corners. Upon completion, the aerodynamic component would have allowed the PNW Motorsports team to more effectively compete at the FSAE design competition in the spring of 2020.
While reducing drag, an undertray provides the capability to direct the air beneath the vehicle chassis in a way which adds “artificial weight” to the system. A pressure gradient of high magnitude is established between the two sides of the undertray, with a low negative pressure region found beneath the body. This design is based upon the principles of fluid dynamics, in particular the venturi effect through the use of nozzles and diffusers. In this fashion, the vehicle can receive the benefits of a heavier car around corners while maintaining the higher straight-line acceleration of a lighter car.
This report describes the use of simulation software in the design of an undertray, as well as the approach to manufacture it. Two-dimensional benchmark cases were performed in the replication of results obtained in a literature search. Subsequently, the undertray model was optimized with CFD and FEA/FEM techniques to obtain a component that was prepared for manufacturing. An operating procedure was established to outline the complicated steps of its assembly. Finally, it provides future aerodynamics teams with a solid foundation upon which improvements can be made.