When the Wind Tunnel Is Not Enough

Steve Remondi co-founded software simulation firm Exa in 1992 with a Massachusetts Institute of Technology professor on the premise that the historical way of building, testing and designing cars is flawed, notably when it comes to achieving superior aerodynamics, fluid flow and thermal efficiencies.

Airflow testing, for example, usually occurs too late in vehicle development, he argues, and if unsatisfactory drag coefficients are discovered, then only piecemeal actions can be taken as sheetmetal and tooling already are set in stone.

But late-stage actions to improve aerodynamics or thermal efficiencies generally add cost for the manufacturer and usually involve adding weight or reducing performance specs via thicker glass, laminated glass, heat shields or dialing back engine output.

In late-phase testing, automakers will discover “they’re failing a test at hill climb, towing, under (certain) conditions, and overheating…so they lower the horsepower of the engine,” Remondi tells WardsAuto.com. “Now you don’t get the horsepower you paid for under that circumstance, but it’s better than overheating. But it’s not as good as delivering the full functionality of the vehicle.”

By bringing aerodynamics and thermal testing into the design process as early as possible, automakers using Exa’s PowerFLOW software can receive feedback via simulations every day, Remondi says.

“Every day you test, every day you get feedback. Not, ‘Oh, I designed for six months, then I wait six months, then I finally go see the wind-tunnel results six months later, and then eventually say, that’s not going to work. What do we do now?’”

Massive, multimillion-dollar wind and/or climate tunnels have become monuments of sorts to automakers’ R&D prowess, usually debuted with splashy grand openings.

But in today’s auto industry, where the cost of doing business is rising and a new-vehicle development program can cost $1 billion, some automakers are eschewing tunnels.

Two of Exa’s clients, Tesla and Jaguar Land Rover, don’t own wind tunnels and designed the Model S and Jaguar XE, respectively, using simulation for airflow and thermal analysis, with Tesla reportedly later validating results in a tunnel.

Jaguar has said it did no verification in a tunnel for the XE, nor did it build a single prototype.

Using PowerFLOW, the Model S coefficient of drag was reduced from 0.32 to 0.27 then finally to 0.24, a Tesla official told SAE in 2013.

“I think the opportunity for these new entrants is to not invest that capital in the old way of doing things, the historical way of building cars and testing and designing them,” Remondi says.

He says Exa can save the ground-transportation industry $3 billion of the $10 billion it spends annually on clay models, test bucks and drivable prototypes, and says automakers in turn will spend “only one-fifth to one-tenth of that on hardware and software to do it through simulation instead.”

Remarkably, there is no standard automakers follow for wind-tunnel construction, which means a vehicle by a certain manufacturer may perform differently from one wind tunnel to another.

It’s a reason Honda, for instance, has given for not releasing its drag coefficients.

“The drag expressed by each wind tunnel is dramatically different, and there are some tunnels that artificially make the drag very low, relative to others, so there are some carmakers that report very low drag numbers that aren’t realistic,” Remondi says.

This variation by tunnel means Exa, when trying to persuade a customer to use its software, must put that customer’s wind-tunnel geometry into the simulation.

“Then (we can) show we compare, giving the customer confidence the data is exactly what they see experimentally, and then we go and we move to the wind tunnel or test facility and put (the vehicle) on the open road and say, ‘Here’s how the car really performs.’

Exa Growing in China

While it has been selling aerodynamic simulation software to the major U.S., German and Japanese automakers for at least 21 years, Exa, of Burlington, MA, is growing its business with a non-traditional clientele as stricter fuel-economy and emissions regulations take hold worldwide.

“We do about three-quarters of our revenue overseas, outside of the United States,” Remondi says.

In the past “overseas” generally meant Europe, as higher fuel prices in the region drove automakers to make their cars as slippery as possible. But now China and developing markets are becoming bigger parts of the software-simulation provider’s revenue.

“We have been engaging in China in the last four or five years – significantly,” Remondi says, noting the supplier has a number of joint-venture and domestic automakers as customers there, but refuses to divulge an exact figure for competitive reasons.

For about 10 years China, trying to counter severe pollution and a strong reliance on imported fuel, has imposed ever-more stringent Corporate Average Fuel Economy Consumption rules on manufacturers. Automakers selling in China must achieve a fleet average of 34 mpg (6.9 L/100 km) this year and 47 mpg (5.0L/100 km) by 2020.

At an industry conference in Michigan last August, China industry analyst Frank Zhao cited a possible 2025 goal of 52 mpg (4.5 L/100 km).

In the past five years, Remondi says he has seen a maturing of the top native Chinese OEMs in which they have elevated their engineering capability and set their sights on becoming “world-class.”

While much of the development work for China JV vehicles has taken place in the U.S. and Europe, more local Chinese vehicle design is occurring. Remondi expects the country to become a significant market for Exa over the next 10 years “as probably five or six of the 20 native Chinese companies become dominant, world-class OEMs.”

In China, using simulation software to ascertain aerodynamics is almost a necessity, as Remondi says there is “basically one major industrywide wind tunnel” that opened in 2009 at Tongji University in Shanghai.

Since 2012, General Motors has operated its own wind tunnel and climate test facility with JV partner SAIC at their Pan Asia Automotive Technical Center in Shanghai.

While Exa counts most major automakers as clients, it still hasn’t won over Japan-based Suzuki.

Of the volume brands, “that’s still the one we haven’t penetrated, but we’ll get them all ultimately. Because we’re the only ones who can really do this.

“But it takes a long time for the car companies to change their processes,” Remondi continues. “They’ve been relying on certain test procedures to verify these cars…and it takes a long time to go prove, application-by-application, stage-by-stage, (that) you can let go (of the old way of doing things).”

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