Canada’s National Research Council licenses low Reynolds Number test facility technology to Aiolos Engineering Corporation

Invention to aid aerodynamic testing of micro aerial vehicles

Ottawa, July 22, 2002 - In a world-first development, the National Research Council of Canada (NRC) has designed and built a pilot-scale facility to study low Reynolds Number flows associated with very small flight vehicles (Micro Aerial Vehicles, or MAVs), vehicles that operate under low air density conditions (High Altitude Long Endurance vehicles, or HALE), and advanced flow control methods. Exploratory tests in the facility were successful and NRC signed an agreement with Aiolos Engineering Corporation in April 2002, granting them sole license to market the technology worldwide. Domestic and foreign organizations can obtain this unique technology through acquisition of facilities custom-designed and supplied by Aiolos, or through collaboration with NRC.

Reynolds Number is a dimensionless quantity related to the flow of a fluid. Acting like a scale factor for aerodynamics, it is proportional to density, vehicle speed and size, and inversely proportional to viscosity. Reproducing the actual flight Reynolds number during testing is therefore important to correctly simulate real conditions.

Developments in nanotechnology that make it possible to build tiny airborne vehicles has generated great interest in low Reynolds Number flows, but the applicable aerodynamics hasn’t caught up. Dr. Ernest Hanff, a Principal Research Officer at NRC, explained, “It’s very difficult to test these vehicles in conventional facilities like a wind tunnel or a water tunnel because the models have to be so small to preserve the correct Reynolds Number that it’s almost impossible to study the flow around them or measure the aerodynamic loads acting on them.” He came up with a solution about two years ago.

Hanff built a 1m x 1m cross section pilot facility to demonstrate the concept of moving a model through a mixture of glycerine and water contained in a tank with no free surface. Glycerine was selected because its high viscosity allows the use of super-scale models, while still retaining the correct Reynolds Number. To eliminate surface waves that cause problems in open facilities such as water tunnels and tow tanks, Hanff completely enclosed the facility and filled it to the top. He also added an inflatable seal in the channel roof slot along which the model support moves. “Our facility has no free surface, so it provides a superior test environment,” he said.

Exploratory tests were conducted on the low Reynolds Number pilot facility to establish performance characteristics and identify improvements. NRC filed for patent protection, then signed the agreement with Aiolos. Work is now underway to adapt modern flow diagnostic techniques to the new test environment. Dr. Gary Elfstrom, Vice-President of Aiolos, said, “This low Reynolds Number test technology, available from Aiolos, represents the first quantum leap in aerodynamic test techniques since cryogenics was applied to high Reynolds Number testing.”

In view of the pilot facility’s success, NRC has provided funds to cover fifty percent of the cost to build a full-scale facility, and is seeking partners to cover the remainder, as well as share in its use. The proposed facility will have a 1m x 1m cross section and be approximately 25m long.

Several organizations, including Canada’s Department of National Defence, the United States Air Force, and researchers in other NATO countries have expressed interest in using the facility to study low Reynolds Number flows and optimize MAV design. Applications for these vehicles are not limited to the military, however. Their ability to fly in confined spaces and acquire visual, acoustic and other information with on-board sensors makes them useful for anti-terrorist activities, search and rescue, drug and contraband interdiction, accident damage assessment and other situations.

“This is a new idea,” said Hanff. “People are trying to do the work in conventional facilities, but the inherent difficulties in using such facilities make progress difficult. Our facility will be able to produce experimental results that nobody else can get.”

Aiolos provides a complete array of services for realization of aerospace and automotive test facilities, including turnkey construction, project engineering and management, maintenance, and feasibility studies for project planning purposes. Typical facilities include aerodynamic and aeroacoustic wind tunnels, climatic wind tunnels, and acoustic chambers. In addition to its headquarters in Toronto, Aiolos has branch offices in Luxembourg, the U.K. and Korea.

NRC undertakes and promotes R&D in support of Canadian and international aerospace communities, in matters affecting the design, manufacture, performance, use and safety of aerospace vehicles. NRC maintains an expertise in, and operates national facilities for, aerodynamic testing, structures and materials research, aeroacoustic research, flight testing, airborne simulation, airborne sensing, aeropropulsion research, combustion, icing research, materials processing technologies, advanced manufacturing, non-destructive testing, diagnostic systems and many other related areas.

Contacts