From the 20th century's De Havilland Dash-8 to the futuristic Bell flying taxi. From Toronto's Commerce Court complex to the Shanghai Tower. From wind turbines and bridges to America's Cup yachts. Since 1970, the NRC's 9 Metre Wind Tunnel facility has been used to test the aerodynamic performance of air, sea, and ground vehicles—and structures from around the world.
Anyone travelling along the Airport Parkway in Ottawa, Ontario has passed a giant white tube feeding into a large building. Few passersby realize that inside the tube is one of the world's largest wind tunnels. Or that inside, manufacturers conduct hush-hush tests on the designs of vehicles as well as buildings, bridges and other structures.
Models used inside can be subjected to winds approaching the speed of tornadoes and hurricanes. Stationary transport trucks and passenger vehicles can be fastened to a treadmill-style rolling road to simulate realistic driving conditions. And submarine and sailboat parts can be examined in dry conditions by using wind to emulate underwater flows.
Celebrating its 50th anniversary this year, the 9 Metre Wind Tunnel is the largest of 6 such facilities operated by the National Research Council of Canada's (NRC) Aerospace Research Centre. The tunnel itself is 274 metres long, and has a volume of some 47,000 m3 (about 18 Olympic swimming pools). The test section floor space is 9 m x 22.9 m, with a ceiling 9 metres high. Over the past 5 decades, it has played an important role in Canada's aerospace, surface transportation, and building industries by giving companies access to a large multifunctional research facility.
According to Adam Kirchhefer, Facility Engineer at the NRC, the tunnel has surpassed its original purpose of testing short takeoff and landing airplanes and helicopters. "In the 1990s, the facility expanded its focus to include the testing of aerodynamics of ground vehicles," he says. "Today, we are busier than ever since we can test a diverse range of air, land, or underwater vehicles or structures—whose performance depends on aerodynamics."
Kirchhefer points out that the original tunnel featured smooth winds like those found at high altitudes. "On the ground, however, the winds are always gusty and turbulent (rough) so one major change we made was to be able to mimic the wind for road and rail vehicles, buildings and bridges."
Where the rubber hits the road
Reducing the aerodynamic drag on large ground vehicles is critical to meeting regulations for cutting fuel consumption and greenhouse gas (GHG) emissions that now drive the industry. "Creating rough winds allows us to provide much more reliable estimates to help manufacturers meet the policies of Transport Canada (TC) and Environment and Climate Change Canada (ECCC)," says NRC researcher Brian McAuliffe. His team also works with TC and ECCC in collaboration with the U.S. Environmental Protection Agency to help them determine what types of regulations are appropriate. "In addition to introducing innovative tests, we built a 30%-scale truck model that allows us to attach scaled full-length trailers for the most realistic testing."
As a project manager for Sweden's Volvo Trucks, North America's Navistar Trucks and numerous trailer technology developers, McAuliffe has guided considerable research into improving fuel economy for massive fleets. This includes everything from using the rolling road in various wind conditions to testing designs for drag-reduction technology such as deflectors and fairings. "We have demonstrated that fuel usage and GHG emissions can be cut by as much as 15%," he adds.
Over the years, McAuliffe has also seen various Automotive and Surface Transportation clients bring in their competitors' products for benchmarking. "This allows them to quickly get a good measure of whose product is better and by how much," he says. "If they find that their competition is ahead, it's a chance to make changes at the design stage to ensure their product is on par or better." He emphasizes that clients feel free to do this since the NRC is bound by confidentiality, and that they are an objective neutral party that provides trustworthy, high-quality data.
Flight plan for the future
Flying taxis have long been a science-fiction fantasy, but Mirabel, Quebec-based Bell Textron Canada Limited is turning them into reality after successfully testing the propulsion system for a flying taxi in the NRC's 9 Metre Wind Tunnel.
"Bell came to us because our 9 Metre Wind Tunnel is the only facility in North America large enough to run the full-scale tests they needed to evaluate the aerodynamics of the propulsion system," says Catherine Clark, NRC Researcher and project manager for the Bell project. "They used the results to develop an urban air taxi prototype that premiered at the 2019 Consumer Electronics Show."
Clark describes the project as "extremely complex," requiring a sizeable research team from both Bell and the NRC to work together for about 7 months, with 6 weeks of research in the wind tunnel. "It was a huge model that we had to test not only for aerodynamics, but also acoustics because they have to fly quietly," she says. These flying taxis are particularly complex because they need to work well in both flight and hover modes. "We tested the propulsion system when going into the wind and in hover modes, as well as transitioning between the two."
According to Edith Richard, Bell's Innovation Leader, the company and the NRC have had a longstanding relationship. "The NRC has a great reputation in the aeronautics industry and we take pride in working with a Canadian partner on Canadian products," she says. "Research allows us to push technologies to improve and innovate in vertical flight."
While Bell's air taxi model was full sized, Clark points out that models can be any size. "Most clients come to us with their own models and we figure out the best way to mount them in the test section," she says. "We can also work in-house with the NRC's Design and Fabrication Services group to build models for clients if needed."
The sky's the limit
Over several decades at the NRC's Aerospace Research Centre, retired researcher and wind tunnel manager Kevin Cooper saw many unusual Canadian and international projects flow through. These included investigations into building and bridge aeroelasticity, overturned train containers, and the aerodynamic designs of dragsters, racing vehicles and passenger cars.
One of the most colourful assignments came from France, where wind tunnel researchers were tasked with examining wind loads on 6-metre-high, 8.7-metre-diameter umbrellas designed by environmental sculptor Christo for installation in California and Japan. According to Cooper, Christo's 3,000 umbrellas for this project had to withstand winds of 88 kilometres per hour winds when open, and 177 kilometres per hour when furled. Stability tests in the 9 Metre Wind Tunnel on a model of the umbrellas verified their wind tolerance before construction began.
"Wind tunnel research has had an immeasurable impact on industry, technology development, and policy decisions as it evolved over half a century," says Cooper. "And I expect that the wide-ranging interests and expertise of the NRC's remarkable teams of engineers and technical staff will continue to propel this facility into a bright future."