Under Tray Diffuser of a FSAE Race car

Running head: UNDER TRAY DIFFUSER OF A FSAE RACE CAR
Under Tray Diffuser of a FSAE Race car
Name of the Student
Name of the University
Author’s Note

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UNDER TRAY DIFFUSER OF A FSAE RACE CAR
Table of Contents
Introduction......................................................................................................................................3
Current Undertray Technology........................................................................................................3
CFD Simulation of Vehicle Aerodynamics.....................................................................................5
FSAE Aerodynamic Devices...........................................................................................................8
Front Wing.......................................................................................................................................9
Conclusion.....................................................................................................................................10
References......................................................................................................................................12

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UNDER TRAY DIFFUSER OF A FSAE RACE CAR
Introduction
Aerodynamic improvements in automotive racing have been a vital effect on the
performance of the vehicle. Recent developments in Formula SAE (Society of Automotive
Engineers) have included in design of aerodynamics devices including inverted wings and
undertrays for improvising performance (Tyagi and Madhwesh 2017). Computational Fluid
Dynamics simulations have been used for iterating design and identify the impact of downforce
developed of several parameters including speed, height and ride. Design of aerodynamic
elements of race cars has been complex
This work focuses on a literature of undertray technology has been presented and design
of an undertray for Global Formula Racing car. An Undertray Diffuser is just as the front and
back wing of race cars. The design of Formula SAE undertray has been developed using CFD
and on-track testing for determining actual vehicle perfirmnece on road.
Current Undertray Technology
The concept of understray has been developed for close proximity of vehicle on ground
and creating a venture effect under the vehicle. Therefore, as like a venture, there will be a
nozzle that helps in increasing speed of the vehicle. This nozzle help in increasing velocity of air
underneath vehicle and throat where maximum throat is provided by the diffuser (Khokhar and
Shirolkar 2015). This condition can be equalize with the Bernouli’s Equation that describes the
local velocity increases relative to free stream velocity as local pressure get decreased. Using
Bernoulli's equation in case of steady, incompressible, in viscid flows along a streamline,
theoretical pressure drop at the constriction is given by
𝑃1 − 𝑃2 = 𝜌 2 (𝑢2 2 − 𝑢1 2)

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UNDER TRAY DIFFUSER OF A FSAE RACE CAR
where is ρ density of fluid, u1 is the slower fluid velocity where pipe is wider, u2 is faster fluid
velocity where pipe is narrower.
Figure 1: Venturi effect Inside a Venturi tube
(Source: Biswal, Prasanth and Naranje 2016)
Downforce can be created by using this low pressure under designed vehicle. The
efficiency of an udertray has been proper as the efficiency of the diffusion. The high visibility
relative to rest of undertray has been creating some misconception in race car industry for
working if diffuser. As argued by Trzesniowski (2017), diffuser helps in creating a downforce of
the undertray and it expands air under vehicle causing lowered pressure.
Figure 2: Race cars use inverted airplane wings to produce downforce instead of lift