Sucess Story CD Adapco STAR CCM Formula FEI Racing Team 2013

8/13/2019 Sucess Story CD Adapco STAR CCM Formula FEI Racing Team 2013

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The design restrictions were:

Formula SAE rules dimensional and position restrictions;

Load tire sensitivity;

Avoid porpoising effects; therefore describe a particular fault encountered in

ground effect in other words fault downforce when the ground clearance is so lowas the suspension height works.

The development of the aerodynamic package design began with the single element

airfoil, multiple elements airfoils, rear wing, front wing and the full car. There was

involving optimum conditions on CFD studies through algorithm tools offered on

software Star-CCM+.

The single airfoil developments focus in obtaining the biggest downforce level and good

aerodynamic efficiency (ratio downforce per drag force). The optimization initiated

based on Selicsairfoils design, which input in a 2D CFD simulation with somecommands variable of a parametric model. There were variable the mains

characteristics of the airfoil: camber angle, thickness and attack angle. Thus the 2D

CFD simulation results the personalize Saboia airfoil.

Image 2: Saboia Airfoil

The multiple element airfoil design used the Saboia airfoil to the dual element

configuration. That based on 2D CFD simulation optimization with command variable ofa parametric model. There were variable the position between main foil and flap, angle

attack, but the flap chord dimension had its proportion with main foil chord locked.

Hence the 2D CFD simulation obtained the best position of the gap interval between

main foil and flap, and the maximum attack angle of the flap.


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Image 3: 2D CFD dual elementoptimization position between main foil and flap.

The rear wing design was used a main foil chord dimension value, which value was

determinate by the targets forces will have with the aerodynamic package, that was

restriction about the load tire sensitivity. Then the flap chord dimension had the same

proportional value studied previously. The 3D CFD model was used to obtain better

approximations with expected results.

Image 4: 3D CFD rear wing

The front wing was a more complex development than the rear wing, because the frontwing has the influence of ground effect and perturbation of the wheels turbulence. The

aerodynamic balance (moment ratio between front wing and rear wing) was defined

rearward with a prediction value. That value was determined by the characteristic of the

dynamic comportment of the car without wings. Then the 3D CFD optimization about

ground clearance variation, there was include the main wing and ground movement with

medium roughness of race track asphalt. That results in a proportional value of ground


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clearance per chord of main wing. After that began the full front 3D CFD optimization

simulation, which included front wheels movement, ground movement with medium

roughness of race track asphalt, the same proportional position between main foil and

flap studied previously, locked with maximum attack angle, the same flap chord at rear

wing, and the variation of chord dimension of the front main wing to obtain the

aerodynamic balance intended.

Image 5: measure the race track asphalt roughness

Image 6: 3D CFDoptimization ground clearance


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Image 7: 3D CFDfront wing optimization chord dimension of main wing

The next step was the full 3D CFD simulation, that was to include the complete car in a

symmetry model with wheels movement, ground movement with medium roughness of

race track asphalt. The keys design factors were ventilation of engine radiator region,

how the turbulence intro the car, and how the turbulence influence of the downforce and

drag force generate. The Formula SAE rules delimit the wing position, that design was

chosen the position of the rear wing as the most rearward possible to favor the

aerodynamic balance, but the height of rear wing was variable to final definition at drag

forces, aerodynamic balance control and take off the almost turbulence intro the rear

wing.

Image 8: 3D CFD full car isometric viewpressure on the body and streamlines.


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Image 9: 3D CFD full car lateral viewpressure on middle plane.

Image 10: 3D CFD full car lateral viewpressure on the body and streamlines.

The final process was the track validation. This track was made in steady state on

straight of the 400 meters, and finally the compare with CFD results. The track

validation consist in instrumentation with strain gage on the pull rods, Pitot tube, position

sensor of damper, ride height sensor and weather station. The strain gage on the pull

rods captured the forces of sprung mass, in others words the forces that go to the tires.

Thus the aerodynamic moment was obtained with a deviation of approximate 20% less

than CFD study.


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Image 11: Instrumentation with strain gage on the pull rod.

Image 12: Prototype FFRT RS8 in track test

All the simulations with software STAR-CCM+ were made in steady state. Thus, below

critical situation which is unsteadiness occur in the body corner. That critical situation

is transient state. However the data from track validation was made in same situation

of CFD studies, and the deviation was small against the others boundary conditions of

real condition, that did not include in CFD simulation. Formula FEI Racing Team is now

a happy STAR-CCM+ user and a lot of confidence was gained in order to improve our

future designs. Thank you Global Academic Program.

REFERENCES

Competition Car AerodynamicsSimon Mc Beath

Race Car Aerodynamics, Design for SpeedJosef Katz

Race Car Vehicle DynamicsWilliam F. Milliken and Douglas L. Milliken

The Steve PortalCD-adapco

Sucess Story CD Adapco STAR CCM Formula FEI Racing Team 2013

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