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SASTECH Journal 72 Volume 12, Issue 1, April 2013

ENHANCEMENT OF AERODYNAMIC

PERFORMANCE OF A FORMULA-1 RACE CARUSING ADD-ON DEVICESB. N. Devaiah

1, S. Umesh

2

1- M. Sc. [Engg.] Student, 2- Asst. ProfessorAutomotive and Aeronautical Engineering Department,

M. S. Ramaiah School of Advanced Studies, Bangalore – 58.

Abstract

Aerodynamics plays a very important role in motorsports. Car manufacturers around the world have been fascinated and

influenced by the various aerodynamic improvements that are used in racing. There has been a constant effort on their side to

incorporate these changes to road vehicles not just as an aesthetic design feature but also since they believe that these features

can contribute to improving fuel economy and vehicle handling. One of the main areas of concern in racing is to balance

aerodynamic forces and to streamline the air flow across the body towards improving stability and handling characteristics,

especially, while cornering. At present, formula racing cars are regulated by stringent FIA norms, there is a constraint for the

dimensions of the vehicle used, engine capacity, power output and emission. It is difficult to obtain the optimum aerodynamic

performance with the existing racing car. There is a need for improvement in the aerodynamic performance of these race cars

by using add-on devices locally with different configurations to streamline and channelize the airflow besides reducing

aerodynamic forces and providing stability that improves cornering and handling characteristics.

In this project work, an attempt has been made to improve the aerodynamic performance of F1 race car by using various

add-on devices with different configurations through steady state CFD simulations. Initially, steady state external air flow

simulation on the baseline model F-1 car without add-on devices has been carried out to obtain air flow pattern around and

for aerodynamic forces using FLUENT solver. A detailed survey on different add-on devices used for racing applications has

been made and geometric models of some add-on devices like front wing, bargeboard, nose wing, rear wheel scallops, roof

spoiler and rear wing with best possible configurations were created and attached to the baseline model. Steady state CFD

simulation on the modified F1 race car with add-on devices has been carried out for different speeds. Aerodynamic

performances like lift force, drag force and their co-efficients are evaluated for different configurations of add-on devices for

different speeds

From parametric CFD simulations on F-1 car attached with add-on devices, there is a considerable amount of drag andlift force reduction besides streamlining the airflow across the car. The best possible configuration for all add-on devices, i.e.

front and rear wings, nose wing, barge board, roof spoiler and wheel scallops, are derived from CFD simulations. The

combination of all these add-on devices with the most appropriate configurations is suggested to incorporate for F1 race car

to improve aerodynamic performance..

Key Words: F-1 Car, Steady State Aerodynamic Analysis, Wings, Add-on Devices, Drag Reduction

1. INTRODUCTION

A Formula-1 car has many add-on devices that aim atreducing the lift and drag forces on the car and there-by

reducing the lap times. But, the lift and drag forces areinversely proportional to each other. Often one tends toignore the fact that the combination of the right

configuration of all the add-on devices is what contributes tothe reduced lap times and not just the design of theindividual add-on devices. For example, the lift reductionachieved by an add-on device, say the front wing, comes atthe cost of higher area being exposed the air leading to an

increase in the drag force, but, the additional downforce isessential for F1 cars as the high speed requires huge amountof traction to improve its stability, especially at corners to

allow high cornering speed. In race cars, especially the openwheel types like the ones used in Formula-1, the add-ondevices play a major role in the lap timings and ultimately isthe difference between the best and the rest. The design of

these add-on devices is also not a simple task with theconstraints imposed by the regulations and also the practicalconstraints. The configuration of the add-on devices is as

important as the design itself, if not more. In order tomaintain desirable handling qualities, the fore-aft location ofthe aerodynamic centre of pressure (CP) is very important.Typically the centre of pressure needs to be located within a

certain distance forward or behind the car centre of gravity.The add-on devices used in the F-1 car model and theirfunctions have been explained in detail in section 2 of this

paper. The rear wing is a crucial component for the performance of a Formula 1 race car. These devicescontribute to approximately a third of the car’s total downforce, while only weighing about 7 kg [7]. Figure 2.1 shows

a rear wing with the airfoil profiles. Usually the rear wing iscomprised of two sets of aerofoils connected to each other

by the wing endplates. The upper aerofoil, usually consistingof three elements, provides the most downforce. The lower

aerofoil, usually consisting of two elements, is smaller and



SASTECH Journal Volume 12, Issue 1, April 2013 73

provides some downforce. However, the lower aerofoilcreates a low-pressure region just below the wing to help thediffuser create more downforce below the car. The rear wingis varied from track to track because of the trade-off between

downforce and drag. More wing angle increases thedownforce and produces more drag, thus reducing the carstop speed. So when racing on tracks with long straights andfew turns, it is better to adjust the wings to have small

angles. On the other hand, when racing on tracks with manyturns and few straights, it is better to adjust the wings tohave large angles.

Splitting the aerofoil into separate elements as shown in

Figure 1 is one way to overcome the flow separation caused by adverse pressure gradients. Multiple wings are used to

gain more downforce in the rear wing. Two wings will produce more downforce than one wing, but not twice as

much. Figure shows the relationship between the number ofairfoils with both the lift coefficient and the lift/drag ratio.

The lift coefficient increases and lift/drag (L/D) ratiodecreases when increasing the number of aerofoils. The

position of the wings relative to each other is important. Ifthey are too close together, the resultant forces will be in

opposite directions and thus cancel each other.

Fig. 1 Cascaded wing with aerofoil profile

Rear wing endplates are designed with form andfunction in mind. Because of their form they provide a

convenient and sturdy way of mounting wings. Theaerodynamic function of these endplates is to prevent airspillage around the wing tips and thus they delay thedevelopment of strongly concentrated trailing

vortices. Trailing vortex or induced drag is the dominatingdrag on rear wings. An additional goal of the rear endplatesis to help reduce the influence of upflow from the wheels.Figure 2 shows a rear wing endplate.

Fig. 2 Endplate design

The front wing of an F1 car has a lot of constraints toolike the rear wing and other parts. It is required to have aneutral central section. This section must be at least 50 cm inlength and cannot induce any amount of downforce, hence

the name neutral central section. There is freedom though inthe number of cascades and the flexibility of the wings, i.e.,the regulations do not specify or limit the number ofcascades and its flexibility. It is found that the stability of a

car, while slipstreaming, improves when the wings areflexible. Also, the closer the wings are to the ground, themore is the downforce that it produces, since it make use ofthe ground effect of the car. But, the regulations specify the

minimum ground clearance of the car at standstill positionwhich cannot be compromised on. Hence, flexible wings areadded which, due to its flexibility, moves down duringcornering which induces a higher downforce on the car and

improves its handling and stability.

Aerodynamic performance enhancement is a veryimportant part of the strategy of any race car team and is asubject of great interest. Many researchers have studied themeans to enhance the aerodynamic performance and also theeffect these changes have on the overall performance of thecar employing analytical and experimental methods. Noah J

McKay and Ashok Gopalarathnam [1] conducted ananalytical study to determine the effects of wingaerodynamics on the performance of race cars and its effecton lap times on different kinds of tracks. Different airfoil

shapes were considered for the design and were analyzedduring cornering, straight line braking and straight lineacceleration conditions. These shapes were tried for singleand dual wing configurations. The results showed the

importance of maintaining a proper lift to drag ratio and thatthe front wing downforce had to balance the rear wingdownforce for optimal results.

Joseph Katz and Darwin Garcia [4] conducted a studyon an open-wheel type, 1/4th scale model of an Indy car toanalyse the aerodynamic components of the add-on devices.

The testing has been done at low speeds in a wind tunnelusing the elevated ground plane method. The aerodynamicloads were measured by a six component balance tomaintain accuracy. It is concluded that the two wings and the

vortex generators generated the maximum downforce andthe major contributors of drag are the wheels and wings.




Michael S Selig and Mark D Maughmert [5] suggesteda method for the selection of the different parameters of anairfoil like the airfoil maximum thickness ratio, pitchingmoment, part of the ve1oclty distribution, or boundary-layer

development. A hybrid-inverse airfoil design technique has been developed by coupling a potential-flow, multipointinverse airfoil design method with a direct boundary-layeranalysis method.

Ashok Gopalarathnam et al [6] conducted a study onthe design of high lift airfoils for low aspect ratio wings withendplates that are extensively used in rear wings of race cars.The induced effects of this setup and the optimum angle of

attack is determined. A parametric study is conducted on theairfoils to study the effects of the constraints due to the

regulations.

Magnus O Johansson and Joseph Katz [8] conducted aseries of experiments on sprint car model in a small scale

wind tunnel to test the effect that the wings can have on thedownforce and cornering ability. They conducted parametricstudies by considering different airfoil profiles andconcluded that the center of pressure can be varied byadjusting the front wing configuration and the modified

airfoil shapes resulted in greater downforce and corneringability.

Car Specifications

The car chosen is the Ferrari F2003 GA and its specsare as shown in the table below.

Table 1. Engine specs

Configuration Ferrari Type 052

Location

Mid-engine, rearwheel drive, longitudinally

mounted

ConstructionAluminum alloy block

and head

Displacement 2,997cc, V10

Valve4 valves per cylinder,

DOHC

Aspiration Naturally Aspirated

Fuel feedMagnetti Marelli Fuel

Injection

Table 2. Dimensions of the car

Weight 600 kg

Length 4545 mm

Width 1796 mm

Height 959 mm

Front track width 1470mm

Rear track width 1405 mm

Wheel base 3100mm

Overall length 4545mm

2. MODELLING, DISCRETIZATION AND

ANALYSIS

Geometric modeling of the Ferrari F2003-GA was done

using the software tool CATIA V5. Fluid domaindiscretization was done in ICEM CFD, which was used as a

pre-processor. Steady state external aerodynamic analysishas been carried out for the three models of the car, namely,(i) baseline model, (ii) baseline model with the front and rearwings attached, (iii) final car model with all add-on devices

attached, at five different speeds of 150 kmph, 200 kmph,250 kmph, 300 kmph and 350 kmph in FLUENT V6 whichwas used as a solver and post-processor.

The geometric model of the F1 car is first cleaned up.The geometry is simplified by closing or filling the tyretreads. This is done in order to ensure that the discretizationor meshing of the model does not fail at the treads because

of it shape and minute size. Figure 3 shows the geometric

model of the baseline car in isometric view. It can be seenfrom the figure that the baseline car does not have any add-on devices. This model is analyzed just to check how the car

behaves at high speeds without the influence of any add-ondevices.

Fig. 3 Geometric model of the baseline car

The next step is to attach the front and rear wings to the baseline car. The baseline model with the wings attached(Figure 4.3) is again analysed for five different speeds of

150, 200, 250, 300, 350 kmph to study the amount ofdownforce and drag force on the car with just the wingsattached and to find how much of an improvement it is fromthe initial baseline model without any add-on devices. The

final step in modelling is to design the add-on devices. Thedifferent add-on devices that are designed are:




Modified Front Wing: The front wings are responsiblefor up to 30% - 40% of the downforce generated in an F1race car. The front wing in the original design does not haveend plates and deflectors on it. This results in the air directly

coming in contact with the front wheels which contribute tothe drag. Hence, the base plate is designed such that thetrailing edges of the plate help in streamlining the flow ofthe under-body air away from front wheels as shown in

figure 4. The deflectors also have the same function ofstreamlining the air around the front wheels on the upper-

body side. As its name suggests, it just deflects the air awayfrom the tyre such that the streamlines get re-attached with

the flow along the car body as soon as it passes the tyres.

Fig. 4 Modified front wing with the base plate and

the deflector

Bargeboard: It is a piece of bodywork mountedvertically between the front wheels and the start of the

sidepods to help smooth the airflow around the sides of thecar. The bargeboard in the car is located just behind the

suspension control arms. It helps in streamlining the flow

around the car body thus helping in reducing aerodynamicdrag on the car. The air after passing through the frontwings, come in contact with the suspension control arms and

the flow-lines become haphazard. The main function of the bargeboard is to streamline this haphazard flow around the body of the car such that it re-attaches to flow through therear wing which is critical in generating downforce. The

design is such that flow of air happens on both the inner andouter edges of the bargeboard and this ensures there is noflow separation. Figure 5 shows the bargeboard design.

Fig. 5 Design and position of bargeboard

Nose wing: The nose wing has an inverted negative liftairfoil shape and is modelled using the NACA 6 series co-ordinates. It is placed just before the suspension arms

assembly of the front wheel on the front nose of the car. Itsmain purpose is to maintain the balance of aerodynamic

moments on the front and rear ends of the car and tostreamline the flow of air above and below the upper controlarm of the double wishbone suspension assembly. The figure6 shows the designed nose wing and its location on the nose.

Fig. 6 Nose wing

Roof spoiler: It is a wing that is placed just above thedriver cockpit and its main purpose is to provide downforce

by streamlining and re-directing the air towards the rear

spoiler. The front and the rear parts of an F1 car has wingsthat generate the required amount of downforce, but themiddle part also must have a sufficient amount of downforceto balance the overall aerodynamic moments on the car. The

basic idea is to keep the centre of pressure as close to thecentre of gravity (CG) of the car to provide maximumstability during operation. Figure 7 shows the roof spoiler

designed of the car.

Fig. 7 Roof spoiler

Rear Wheel Scallops: The rear wheel scallops positioned just in front of the rear wheels serve the purpose

of streamlining the air coming from the bargeboard and thefront wings towards the rear wing and away from the reartyres. This helps in generating downforce and also reducesthe drag force on the car. The rear wheel scallops are

designed such that the stream of air passes on both its facesand re-directs it away from the rear tyres thereby reducingthe drag force and helps in knocking off a few crucial milli-

seconds off the lap times! Figure 8 shows the rear wheelscallops.




Fig. 8 Rear wheel scallops

Rear wing: The two main parts of the rear wings arethe cascading wing profiles and the end plates. The rear

wings produce downforce towrds the rear end of the car.Most of the contours on the car are designed such that they

streamline the air into the rear wings so as to induce thelargest amount of downforce. Another important part of the

rear wing is the beam wing. It is the lowest wing section andis very strictly regulated by crash test regulations. It is alsoquite heavy sine it supports the whole wing and some carsuse it as a part of the chassis also.

Fig. 9 Rear wing

Figure 9 shows the model of the F1 car after all thedesigned add-on devices have been attached.

Fig. 10 Model with all add-on devices

Figure 10 shows the discretized model of the car with

all add-on devices and the different mesh sizes adopted inorder to save computational time, without compromising onthe accuracy of the results.

Fig. 11 Discretized model of car with all add-on

devices

3 DISCUSSION OF RESULTS AND

VALIDATION

The results from the steady state analysis carried out onthe three models of the F-1 car are discussed in this chapter.

The performance and the aerodynamic forces and theircoefficients are analysed by simulating at five different

speeds of 150, 200, 250, 300 and 350 kmph for all the threemodels.

3.1 Solver settings and parameters

The solver settings set in FLUENT software for thesimulation is as shown in the table 3

Table 3. Solver settings

Solver type 3d- pressure based

velocity absolute

flow steady

viscosity model Turbulent (K-epsilon)

The other settings that have to be specified for the

simulation are the boundary conditions. Table 5.2 gives the boundary conditions set in Fluent software for the analysis.

Table 4. Boundary Conditions

Parts Boundary Conditions

Car body Stationary wall, no slip

Add-on devices Stationary wall, no slip

WheelsRotational wall with

specified angular velocity

Domain bottom wallTranslational wall with

specified velocity

Domain top, left

and right walls

Stationary wall, with

specified shear condition

Domain Inlet Velocity Inlet

Domain outlet Pressure outlet




3.2 Results

The baseline model of the F1 car is simulated and theresults are as tabulated in table 5.

Table 5. Comparison of aerodynamic forces at

different speeds for baseline model

Baseline Model

Car

Speed

Drag

ForceCd

Lift

ForceCl

150 1215.49 0.7866 439.74 0.2846

200 2158.84 0.7865 766.80 0.2826

250 3375.14 0.7865 1207.39 0.2814

300 4860.24 0.7865 1732.39 0.2803

350 6613.07 0.7862 2363.45 0.2810

Fig. 12 Variation of drag force (N) v/s speed

(kmph)

Fig. 13 Variation of down force (N) v/s speed

(kmph)

Figure 13 shows the contours of pressure distributionand velocity distribution along the center plane in x-direction. High pressure points can be observed at the nosetip, the front wheel, the body of the car and the area behind

the cockpit. The velocity plot shows stagnation points on the

car body and regions of low velocity just behind the car(wake region), which is considerably large.

Fig. 14 Contours of pressure and velocity

Fig. 15 Pathlines seen from the side view

showing streamlines along the body

The model of the F1 car with all the add-on devices that

have been designed, like, the bargeboard, nose wing, frontwing modifications, roof spoiler, rear wheel scallops and the

rear wing are attached is analysed and simulated and theresults are as tabulated in Table 6.

Table 6. Comparison of aerodynamic forces at

different speeds model with all add-on devices

Model with all add-on devices

Car

SpeedDrag

Force (N)Cd

Downforc

e (N)Cl

150 1353.72 0.7814 346.63 -0.200

200 2404.78 0.7808 620.95 -0.201

250 3754.96 0.7805 976.01 -0.202

300 5407.41 0.7806 1413.07 -0.203

350 7357.34 0.7802 1929.99 -0.204

Both the drag and lift forces are increasing withincrease in speed. The variation in the drag and lift forceswith speed is almost linear as shown in figure 5.17 and 5.18respectively.




Fig. 16 Variation of drag force (N) v/s speed

(kmph)

Fig. 17 Variation of down force (N) v/s speed

(kmph)

4. COMPARISON OF RESULTS

The results for the three models are compared and thechanges in their aerodynamic forces and co-efficients are

analysed. The comparison of these values at different speedsis as shown in table 5.10. In table 5.10, baseline stands forthe baseline model of the car, wings only stands for the carmodel with the front and the rear wings attached and all add-

ons stands for the car model with the modified front wing,rear wing, bargeboard, nose wing, rear wheel scallops andthe roof spoiler attached.

Table 7. Comparison of aerodynamic forces and

their co-efficients of the three models at a speed of

200 kmphDrag Force

(N)Cd

Downforce(N)

Cl

Baseline 2158.85 -0.7859 766.81 0.2791

Wingsonly

2571.81 -0.8406 -798.77 -0.2611

All add-ons

2404.78 -0.7809 -620.95 -0.2016

Figure 17 shows the drag force variation for differentmodels. It can be seen that the drag force is least on the

baseline model which is understandable since it has a verysmall frontal projected area. The drag force is less on the

model with all add-on devices when compared to the modelwith only the front and rear wings attached. Figure 18 showsthe drag co-efficient variation and it follows the same patternas the drag force.

Fig. 18 Graph showing variation of drag force

for the different models

Fig. 19 Graph showing variation of drag co-

efficient for the different models

Fig. 20 Graph showing variation of down force

for the different models

The variation of downforce and its co-efficient are as shownin figure 19 and 20. It can be seen that the add-on devices

have reduced the drag but, at the expense of reduceddownforce. But the reduction in the lift co-efficient is very

small.




Fig. 21 Graph showing variation of lift co-efficient

for the different models at 200 kmph

Table 5.8 shows the lift to drag ratio for the three models.The L/D ratio gives the ratio of lift force by drag force. The

variation of L/D ratio for the three models is shown inFigure 5.30. The lowest L/D ratio (0.258) is for the modelwith all add-on devices attached. Hence it can be seen thatthe model of the car with the designed add-on devices

attached gives the best L/D ratio and the best configurationof add-on devices is arrived at.

Table 8. L/D ratio for the three models

L/D Ratio

Baseline model 0.355

Model with

wings attached

‐0.310

Model with

all add‐ons ‐0.258

Fig. 22 Graph showing variation of L/D ratio for

the different models at 200 kmph

5. CONCLUSION

In this project work, an attempt has been made to improvethe aerodynamic performance of F1 race car by using

various add-on devices like front wing, bargeboard, rearwing, nose wing, roof spoiler and wheel scallops with

different configurations through steady state CFDsimulations.

A comparison was made with the baseline model , car

with wings attached and the car with all add-on devicesattached and the following points were concluded:

A reduction of 10.22% and 4.75% in the drag

force and drag co-efficient respectively is seen inthe model with all add-on devices when compared

to the baseline model.

There was a reduction of 6.5% in the drag forceand 5.4% reduction in the drag co-efficient in the

modified model with the add-on devices whencompared to the model with only the wings

attached.

The downforce and the lift co-efficient were seen

to increase by 2 times for the model with all add-on devices attached when compared to the baseline

model. There was an increase of 22% and 15% in the

downforce and lift co-efficient in the modified

model with the add-on devices when compared tothe model with only the wings attached.

6. REFERENCES

[1] McKay, Noah J, 2002. “The Effect of Wing

Aerodynamics on Race VehiclePerformance”. SAE Publications

[2] Gregor Seljak, 2008. Race Car Aerodynamics.

[3] 2011 FIA Regulations

[4] Katz, Joseph and Garcia, Darwin, 2002.

“Aerodynamic Effects of Indy car components”.

SAE Publications[5] Selig, Michael S and Maughmert, Mark D, 1992.

“Generalized Multipoint Inverse Airfoil Design”AIAA Journal, Vol. 30.

[6] Ashok Gopalarathnam et al, 1997. “Design of

High Lift Airfoils For Low Aspect Ratio WingsWith Endplates“ AIAA Journal

[7] BMW Sauber F1.07 Development: Analysis &

Drawings. 2012. BMW Sauber F1.07

Development: Analysis & Drawings. [ONLINE]

Available at:

http://www.f1network.net/main/s491/st122735.htm?print=1.

[8] Johansson, Magnus O and Katz, Joseph, 2002.“Lateral Aerodynamics of a Generic Sprint CarConfiguration“ SAE Publications

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