Engineers at Voxdale had the opportunity to work with Anthony Kumpen, overall winner of the 2014 and 2016 NASCAR Whelen Euro Series season, to investigate how the performance of his racing team's car could be improved.
NASCAR is a closed racing series with a tight rule book and stringent regulations. Ignore or break them and lose the race even if with the fastest car on the track. That’s why technology (within bounds) plays an important role in helping NASCAR teams maintain a competitive edge.
Engineers at Voxdale in Belgium had the opportunity to work with Anthony Kumpen, overall winner of the 2014 and 2016 NASCAR Whelen Euro Series season, to investigate how the performance of his racing team’s car could be improved. NASCAR racing cars in the United States usually have a V8 engine and as much as 800 horsepower. Although the U.S. rules and standards are adopted in the NASCAR Whelen Euro Series, the cars are built specifically for European tracks and their horsepower is restricted to 450 hp.
Whatever the NASCAR series, all of the racing cars’ modified builds are restricted by regulations. Only the car body silhouette resembles the original car. The regulations dictate, for example, a limited size for the rear spoiler, the chassis material thickness, and the allowed production processes used for the engine cylinders. Often, winning team cars are dismantled by NASCAR officials after a race to check for any irregularities. With such strict compliance requirements, the car performances are nearly equivalent. Only a few rare opportunities are available to gain any technical advantage. This means that the racing teams need to find ways of making small gains wherever they can to improve their performance.
Mentor’s specialists in thermal simulation and analysis met with Anthony Kumpen and Koen Beyers, CEO of Voxdale BVBA engineering consultancy, to see how they could use computational fluid dynamics (CFD) technology to improve their car. (Figure 1). Voxdale engineers collaborated with Kumpen’s team to optimize their racing car using Mentor’s CAD-embedded, CFD-simulation software FloEFD.
Fig. 1: Anthony Kumpen (left) and Koen Beyers (Photo: Mentor)
Kumpen explained how racing has to be supported by good engineering. “Motorsport is something very different. You have to be in it to really understand. I’ve been doing it all my life, and I couldn’t even think about my life without racing. There are so many aspects that are interesting. As a driver, you have the driving aspect, which is really interesting, and the adrenaline and everything that you get from that. It’s also all about details and working with engineers and the mechanics. There’s a lot more than just driving fast in a car. It’s making the car faster, improving everything. That’s what racing’s all about.”
Kumpen’s team understood going in that aerodynamics was really important to be competitive in NASCAR. So they looked for a local engineering partner who was working in aerodynamics. Designing and analyzing the aerodynamics is an expensive process, and the best data is gathered from inside a custom wind tunnel. But, for a small team just entering NASCAR, building a wind tunnel was beyond their scope. Instead, the engineers at Voxdale, who have experience in racing aerodynamics, helped the racing team run many simulations, the equivalent of having their own wind tunnel.
“Finding the right partner to improve your car is really important. Voxdale did all the simulations for us. With that data, we started improving our cars right away, so we’re really happy with that collaboration,” said Kumpen.
When the engineers first got involved in the NASCAR project, the first challenge was to figure out what was actually possible, what they could and would be allowed to do. For instance, the body work could not be changed nor could the manifolds or engine parts. Kumpen’s team and Voxdale engineers decided to analyze the car’s aerodynamic mapping and overall behavior. They investigated the internal air flow, as well as the air flow underneath the body and over the hood (Figures 2–6).
Figure 2: Velocity streamlines on the car’s body surface and isosurface around the body.
Figure 3: Pressure coefficient
Figure 4: Velocity profile under the car
Figure 5: Velocity profile under the car and wheelhousing
Figure 6: Velocity profile under the car body and pressure distribution on the spoiler
They were able to optimize cooling of the brakes and the exhaust system. The modeling of the CAD geometry took around three days, and the thermal simulation setup took about a day. The engineers conducted around 10 simulations directly within the CAD environment, which took about two weeks including post-processing.
Their optimizations also had to accommodate variations in the racing track. In one track, it’s better to have as little downforce as possible to make the car run really smooth; whereas, in another track, greater downforce is desirable. The more data that can be gathered about the car, the better the car will perform on the racetrack.
“At one point, we saw the effect of a specific riding height combined with an explicit rake angle resulting in a drag reduction of 0.8%. Over one lap at Brands Hatch, with this car with this power, this buys you 0.2 second. An important leap in a closed racing series,” Beyers explained.
Kumpen’s team was able to quickly apply what they learned from the simulations, testing the results on the track. The ultimate verification was, of course, winning.
As Kumpen said, driving is just a small part of racing. “Being a racing driver, everybody thinks you spend all the time in the car. Actually, I spend 80 percent of my time in meetings with my engineers, with my chief mechanics, trying to help them improve the car. Then, translate my feeling that I have when I’m racing, or when I’m testing the car, into improvements on the car. You have to work a lot with engineers. You have to be able to talk to them on a level that they can improve your car. Engineering is something that we have to study every day to be a good driver. And we are winning a lot of races. It’s all about the details of racing and finding the right partners.”
-- This contributed article was co-authored by Koen Beyers, CEO at Voxdale and Mike Gruetzmacher, Mentor, A Siemens Business.