Imagine the worst weather in the world – a temperature of 40 below, with a Category 3 hurricane blowing through. Now, imagine driving a car into that wind at more than 200 kilometres an hour.
This is what can happen in the aerodynamic wind tunnel at the Automotive Centre of Excellence (ACE), on the grounds of Ontario Tech University, the easy-to-remember brand name of the University of Ontario Institute of Technology in Oshawa, Ont.
This wind tunnel has existed for more than a decade, but now it’s been upgraded to include a “moving ground plane” that simulates driving on an actual road.
”This belt is not a treadmill,” says ACE executive director John Komar, who calls it a “rolling road” and says it is the only facility of its kind in the world.
The seven-metre belt on the rolling road allows a test vehicle to simulate driving without the inevitable turbulence that would be stirred up if a static floor was beneath it. This smooth flow cannot be reproduced for a stationary vehicle strapped to rollers, which is what other wind tunnels offer. On the rolling road, the vehicle has no suspension but is supported by external arms on each wheel, pressing down with precise force against the belt, which spins at the same speed as the wind and exists to turn the wheels and vacuum away the turbulence.
“Significant improvements in drag have occurred using the last 20 years of wind-tunnel technology,” Komar said. “But now, to make a 10-per-cent improvement in drag may require 20 half-per-cent improvements. That means a more realistic underbody-flow and wheels-turning simulation is required. That also means that an exponentially more accurate and sensitive rolling road and force-measurement system is required to accurately and repeatably identify small changes.”
Designers know the optimum shape for a vehicle to cut through the wind with the least resistance, but “the new frontier for advanced mobility is under the vehicle,” said Komar. “The use of advanced technologies, sensors and artificial intelligence will drive efficiencies and vehicle requirements.”
The rolling road can measure forces down to single newtons, and can be adjusted on a horizontal, 360-degree turntable within fractions of a degree.
“If you’re working on underbody aero[dynamics], that’s where it becomes really critical” to use the rolling road, said Todd Deaville, director of corporate engineering and research and development for Magna International Inc. “Aero is a very large portion of energy consumption, and the underbody is a significant portion of that.”
Magna is a sponsor of the ACE facility. The federal government also contributed $9.5-million toward the rolling road’s purchase and installation.
“I can’t say too much about how we’ve been using it,” said Deaville, “but if you think about it, we are a leader in active grille shutters – so active aerodynamics on vehicles on the road today. That’s an area of interest for us.”
Komar said ACE bought the rolling road second-hand from NASA, where it was installed but never used at Old Dominion University in Virginia. “I couldn’t afford a brand-new one – a rolling road is $20-million, and that’s not including the integration.”
It was reconfigured for the Oshawa wind tunnel. However, if rain and snow is needed, engineers will swap out the 80,000-kilogram rolling road for the traditional 129,000-kilogram dynamometer that was already installed, which has rollers for the test vehicle and is impervious to water.
Komar said no other wind tunnel in the world includes both a moving ground plane and a dynamometer. They are each stored beneath the tunnel’s floor and can be rolled into position in just a few hours.
When the dynamometer is in place, the tunnel can produce blizzards and rain storms, or be heated up to 60 degrees Celsius. Humidity can range from 5 to 95 per cent.
It’s been used for research by motorsport teams, the Canadian national ski team and even by first responders to practise rescue techniques in severe cold. It can cost up to $3,000 an hour to rent and Komar says it’s already booked for much of this year.
“The whole point is, you have to be accurate, you have to be repeatable, and you have to be reproduceable,” said Komar. “I should be able to come back a year from now, or 10 years from now, and get the exact same results.”
About 1,500 students from the school get to use the facility each year, but it’s not all work.
“We have orientation weeks where we have some fun,” said Komar. “We played the [storm chaser] movie Twister one night. We had a little tiki bar and they all brought in their mats, and when the tornado came, we blew the wind and the rain came down. You know what? Science is fun.”