Extreme ice

Extreme ice

Eager to develop new safety techniques, University of Manitoba researchers are using a unique new wind tunnel to simulate the icy conditions that threaten aircraft and hydro-electric infrastructure
November 1, 2004
Canada's weather runs from one extreme to another. The University of Manitoba is the only place in the world with an icing wind tunnel that can boast a similar range.
 

The University's Thermofluids Engineering Laboratory-or icing wind tunnel-is the only facility of its kind that enables researchers to study the full spectrum of icing conditions in extreme conditions, literally from the ground up.

The two extremes in weather occur from high-altitude icing experienced by aircraft, and the ground-level icing typically found on hydro lines, wind turbines, and other structures. "To our knowledge, all of the other icing wind tunnels can do one or the other," says Greg Naterer, lead researcher at the Thermofluids Engineering Laboratory and an Associate Professor at the University of Manitoba. "Ours is the only one in the world that can do both-it's a first."

Naterer and his fellow researchers accomplished this "first" by designing the facility with removable modules and components so that different conditions can be simulated. This includes removable and adjustable water spray bars so the distance between the spray and the test objects can be adjusted-because different conditions require different temperatures, air speeds, and droplet sizes. "There are two types of icing that we're studying. There is aircraft icing, with high speed, high altitude, and small droplets about 10 to 20 microns in size," says Naterer. "The other type of icing is on the ground, with precipitation at low speeds and droplets up to 1 millimetre in diameter, which is about 100 times the size of the droplets at high altitude."

Naterer says the decision to create the unique facility was made after the university was approached by two different research collaborators at opposite ends of the spectrum. One of Naterer's co-applicants for CFI support, Neil Popplewell, had been conducting research for a few decades on the icing of hydro lines and worked with Manitoba Hydro, which wanted to conduct further research. About the same time, they were also approached by Westland Helicopters, the manufacturer of Canada's new state-of-the-art search-and-rescue helicopters -a candidate for the Canadian military's replacement for the aging Sea King helicopters.

In just under a year since opening, the lab has conducted significant, valuable research for both these partners. Westland was experiencing ice build up on an engine bay cooling intake, which brings in cool air to avoid engine overheating. This can lead to problems and issues of safety in flight. "One of the innovative features that's being developed in the wind tunnel is a series of micro grooves on the helicopter surface to shear off water droplets," says Naterer. "The grooves interfere with the air flow just enough to allow the air into the engine, while deflecting the water droplets which would turn to ice."

Closer to the ground, work done for Manitoba Hydro is helping them design stronger towers and hydro lines that would be less prone to icing up, both in a more cost-efficient manner. "We can do testing to see what happens when ice builds up. We have developed predictive design tools, which will allow Manitoba Hydro to better predict a margin of safety during construction," says Naterer.

Benefits

The massive ice storm that hit Eastern Canada in 1998 caused billions of dollars in damage as hydro towers, poles, and lines collapsed under the weight of ice build up. The ensuing power outages resulted in business shutdowns, spoilage of goods, and months of infrastructure rebuilding.

Icing can have consequences that are just as serious for aircraft-both in the air and on the ground. Canada's last major accident involving wing icing was the crash of a Fokker f-28 at Dryden, Ontario, in March 1989. A build-up of ice on the wings prevented the plane from lifting off and 24 people perished.

In another incident, on October 31, 1994, American Eagle Flight 4184 crashed and disintegrated killing 68 people southeast of Chicago's O'Hare Airport after ice built up on the wings. The investigation led to all ATR-72 aircraft being retrofitted with de-icing equipment.

The research taking place at the University of Manitoba's Thermofluids Engineering Laboratory provides a cost-effective way to test theories and reduce the risks associated with costly icing flight trials that aircraft have to undergo to obtain certification.

"Any time there is a change to a surface or a new surface, they have to do icing trials, which is very costly and risky," says Greg Naterer, lead researcher at the Thermofluids Engineering Laboratory and an Associate Professor at the University of Manitoba. In the wind tunnel, these effects can be duplicated without risking a pilot's life or losing an aircraft. Ultimately, Naterer sees certification occurring without a flight even taking place.

The Laboratory can also help improve existing processes and generate cost efficiencies, such as in the case of heating systems designed to keep surfaces above the freezing point. "Surface heating is very costly," says Naterer. "By studying the effective placing of surface heating, targeting the surface heating to areas that need it most, and testing different surface coatings that reduce ice adherence, we can reduce those costs."

In addition, Naterer sees the icing wind tunnel dramatically reducing design and construction costs for infrastructure that needs to withstand the crushing weight of ice build up. "You can always build a super strong support, but with increased costs," he says. "This gives us a better idea of limits and thresholds so you can design with just enough strength and factor-in the economics."

Partners

The University of Manitoba Thermofluids Engineering Laboratory is less than a year old but it has already attracted major partners eager to share in and benefit from its research.

Westland Helicopters — Westland Helicopters is a British company that makes the EH-101 Search and Rescue helicopters used by the Canadian Forces. Another version of the helicopter is in contention to replace the Canadian Forces' aging Sea King Helicopters. Westland has provided $109,500 for icing wind tunnel research, $40,500 of which was used to match CFI infrastructure funding.

Manitoba Hydro — Manitoba's major energy utility serves 499,535 electricity customers and 249,351 gas customers in the province. Virtually all electricity generated by the provincial Crown Corporation is from self-renewing water power. One system is the Nelson River Transmission System comprised of 4,103 hydro towers with an average height of 38 metres. The two-line system has one line that's 895 kilometres long and the another 937 kilometres long. Manitoba Hydro contributed $79,204 to match CFI infrastructure funding and an additional $41,940 for research.

Western Economic Diversification Canada — This federal government department promotes the development and diversification of the economy of Western Canada. It also advances the interests of the West in national economic policy. It contributed $265,000 for additional enhancements to the lab's infrastructure.

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