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Author: Nicolás Gómez Osorio, UPMRacing, Universidad Politécnica de Madrid This year at Silverstone, where we are the only car with a full aerodynamic package even though some teams have ground effect plates we studied in CFD the three items in our car: the back and front wings and the ground effect plate with a keel. Our goal was to reach up to -1 value in the CL, indeed we reach almost -1.5.
First, we started our simulation having the basic forms our body work and after we gathered some info like lift and drag coefficients, and the forces in the car at 55km/h we started to introduce item by item and comparing the results. 
The simulation was done with the two equations model K-epsilon, the mesh used more than 4 million cells, we use specific mesh for different zones making it smaller for example in the zone we thought we could have some detachment of the boundary layer. We used tetrahedra cells and as you can see we use a symmetry plane in the middle of the car. Figure 1. Mesh.( Fluent Study) | 
The first item to be introduce was the ground effect plate with the keel, the keel is an element that you don’t see it quite often in formula SAE, nevertheless in F1 the teams have three different simple configurations, double or “null keel” the last as no keel at all, for us this item had two functions splitting the air flow in two in order to feed the side pots properly and also giving us some extra down force by increasing the pressure above the front of the ground effect plate. In figure 3 you can see the keel and the ground effect plate. Figure 2. For the zones far away of the model the cells had linear increment. (Fluent study) |
Figure 3. The keel and ground effect plate (Catia design) In figure 4 it can be seen how the keel give some over pressure over the first part of the plate. 
Figure 4. Pressure distribution (Fluent study)
As for the ground effect plate we decided put fit three diffusers basing our length and angels in the book Race Car aerodynamics of Joseph Katz, for this reason, we try to maintain an angle of no more than 11degrees in any of the diffusers, the results of fitting the ground effect plate were quite good, we raised the lift coefficient in almost six times it original number it went from 0.054 to -0.28. The most outstanding feature of the under body work it’s to stabilize the flow after the car and reducing the turbulence behind it as you can see on figure 5. 
Figure 5. As it can be seen in the first image the turbulence in the car whit no under bodywork it’s huge , in the lower photo the flow reduces its turbulence specially in the center of the car .
As for the front wing we used an a configuration of two airfoils, with more angle in the ones near to the wheel, the results of the wings were also very pleasant because we reach a total of 115 Newtons of down force. In figure 6 you can see the static pressure contours.
Figure 6. front
In the rear wing we had also two airfoil configuration and as it is well known the rear wing provides more down force than the front wing, for the rear wing the simulation gave us a value of 130 Newtons of down force in figure 7, you can see a middle plane cut of the rear wing velocities.
Figure 7. rear
In the end, we reached a peak of 212 N of down force with the whole pack of aerodynamic items, the weight of the total 3 items did not exceed the 100N, and as it was said a CL of -1.48. As a resume, here is the table with all the forces that we presented to judges on the design.
| | Aerodynamic devices configuration | No Aerodynamic devices configuration | Lift (N)
| Drag (N)
| Lift (N)
| Drag (N)
| Front Wing
| -116,4 | 14,4 | | | Rear Wing
| -130,1 | 30,1 | | | Bodywork
| 15,2 | 24,3 | 10,9 | 16,1 | Ground Effect Plate
| -52,4 | 1,0 | | | Front Wheels
| 15,4 | 19,4 | 18,6 | 29,4 | Rear Wheels
| 12,6 | 14,6 | 6,6 | 10,6 |
Figure 8. Comparison between the aerodynamic devices and the body work alone | | With | None
| L (N)
| -212,8 | 35,7 | CL
| -1,48 | 0,25 | D (N)
| 110,1 | 59,4 | CD (N)
| 0,81 | 0,44 |
Figure 9. Resume of the lift and drag coefficients with and without the aerodynamic devices
As a final result, we’ll show the three stages of our study.
 
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Comments
It`s amazing!!!!
I love UPMRacing!!
What are your additional wheights from the aerodynamic components? And did you verify your simulations at a wind tunnel?
Here in the US their are a few teams with aerodynamics, but as I can remember UPMRacing is one of the only teams in Europe?
It was about 12Kg becouse we had a problem (money) and the ground effect plate was´nt entire of Carbon fiber , the front and the rear wing (idont remember theexxact number) about 3 KG each an the ground effect plate another 6 , for next year we want to make no more than 7Kg .
To second question yes I haven´t seen any other team with that aerodynamic development , only USA( UTA or UMR) and in Australia (Auckland)