“We speak the same language in venti­lation tech­nology”

Formula One and venti­lation tech­nology have more in common than it might appear at first glance: Both racing teams and fan manu­fac­turers employ the latest mate­rials and look for ways to reduce weight and network their prod­ucts with their envi­ron­ment. Joint inter­ests also exist in the field of aero­dy­namics. What these are and just how impor­tant aero­dy­namics is to Formula One is explained by Geoff Willis, Tech­nology Director of the MERCEDES AMG PETRONAS Formula One Team, in the following inter­view.

Which common factors and differ­ences exist between Formula One cars and fans in your opinion?

CFD image of an axial fan: The warmer the colour, the higher the flow velocity.

In our deal­ings with engi­neers from our Team Partner ebm-papst it became apparent that our work is actu­ally very similar. Whether we are working on fans or on Formula One, we often employ the numer­ical methods of compu­ta­tional fluid dynamics (CFD) and are constantly looking to improve our prod­ucts. What’s more, the activ­i­ties at both ebm-papst and MERCEDES AMG PETRONAS revolve around low-speed aero­dy­namics*.

So the engi­neers speak in the same terms regard­less of whether they are talking about fans or Formula One. The differ­ences lie in the solu­tions we develop and the types of flow involved in our work. Whereas rotating flows play a major part with regard to fans, we are primarily concerned with the so-called ground effect which arises as a result of producing down­force so close to the ground.

*Low-speed aero­dy­namics refers to the branch of aero­dy­namics involving flow veloc­i­ties of up to approx. Mach 0.3.

How many members of your team work on the aero­dy­namics of Formula One cars?

There are around 70 aero­dy­namics experts, engi­neers and special­ists in our team who are directly involved with this topic. On top of that there are another 80 people who provide tech­nical support in this field. They design and construct the models or are respon­sible for the tech­nical aspects of the wind tunnel. To help coor­di­nate the work, the aero­dy­namics depart­ment is divided into several sub-groups. Each of these has all the resources it requires to concen­trate on a certain part of the car or specific tasks.

What are the most impor­tant aspects of your work in the area of aero­dy­namics?

One aim is to increase the down­force to give the cars better grip and to permit faster cornering. We also look for ways to reduce drag, as this saves fuel and helps us achieve better lap times. But the most impor­tant thing – as the drivers are always telling us – is the vehicle balance. A car has to have the right amount of grip at the front and rear and at the same time handle well on cornering. Which is why we some­times sacri­fice a bit of absolute down­force in the inter­ests of obtaining a more consis­tent down­force.

How do you go about measuring balance?

Nowa­days we have the means to gather plenty of data which provides us with infor­ma­tion on all the forces acting on the car and how we can alter these. The finer details however come from the drivers. They can give us a better idea of how quickly the forces build up on entering a corner for example. So their feed­back is vital to our work.

What devel­op­ments have there been over the past few years with regard to the aero­dy­namics of Formula One cars?

Pictures of aero­dy­namics in auto­mo­tive oper­a­tion

Frequent changes to the rules have brought a lot of new chal­lenges with them, leading to certain signif­i­cant modi­fi­ca­tions in recent times. One of the areas concerned has been the aspect of safety. This has involved modi­fying the geom­etry of the car to provide better protec­tion for the driver and reduce the amount of damage in the event of colli­sions. At the same time it is of course always impor­tant to keep an eye on the effect of such changes on the aero­dy­namics.

The new gener­a­tion of turbocharged hybrid power units intro­duced in 2014 presented us with another inter­esting chal­lenge. With a turbo-charged engine, we have to cool the combus­tion air exiting the compressor, which can be well over 200C, before it enters the engine so we need signif­i­cant extra cooling capacity in the car. This means that we have to trade off engine perfor­mance with chassis perfor­mance.

It would be easy to imagine that Formula One cars are already so sophis­ti­cated that there cannot really be much room left for improve­ment. So where do you keep getting new ideas from?

The more we learn about how the car func­tions, the more we discover poten­tial for further enhance­ment. In partic­ular, we are gaining a better under­standing of the inter­ac­tion between the various design compo­nents of the car, enabling us to engage in an ongoing improve­ment process based on a compre­hen­sive approach. And our capa­bil­i­ties in the areas of simu­la­tion and virtual engi­neering are growing to match the increasing complexity of the tasks.

You mention computer simu­la­tion. What is the purpose of this proce­dure and how impor­tant is it in rela­tion to testing in a wind tunnel and on the track?

In all areas, the number of tests and the test times are subject to tight restric­tions. The propor­tion of wind tunnel tests to computer simu­la­tions is 50:50. Ten years ago, CFD methods were limited capacity so were used as analysis tools, mainly on concepts after they were tested. These days they form an inte­gral part of our design process. Testing on the track is of course impor­tant as well, but we only have the oppor­tu­nity to do so before the season starts and twice during the season. We some­times also run aero­dy­namic exper­i­ments on the Friday of a race weekend. So from the point of view of time, these tests are of lesser signif­i­cance. The impor­tant thing is that we manage to combine all the elements of wind tunnel, CFD and track testing in a construc­tive way to come up with new find­ings.