Subsonic Wind Tunnels

Both basic research and applied aerodynamic studies can be conducted in our 3'x5' subsonic wind tunnel, an open circuit facility with low turbulence and with a top speed of 150 ft/sec, that is used extensively for studies of wind turbine aerodynamics.

When equipped with an apparatus to oscillate airfoils, unsteady aerodynamics on wind turbine airfoils was examined the dynamic effects were shown to increase the rotor air loads more than 50% above the static air loads. These rotor dynamics results, and others that include airfoil performance degradation with insect and ice contamination, were passed on to manufactures. Other important research projects include the performance evaluation of an airship with a set of wings to provide aerodynamic lift to assist its buoyancy, and the development of vortex generators for the canard of the Voyager aircraft, to prevent rain from disrupting the flow above the canard and stalling the aircraft.

The subsonic wind tunnel has been used extensively for wind energy machine studies. Specialized airfoils for wind turbine rotors has been examined and their performance passed on to turbine manufacturers. The wind tunnel was equipped with a system to model the unsteady aerodynamic influence on turbine rotors. Measurements of these dynamics effects showed that rotor airloads can be increased by more than 50% above static airloads.

Recent subsonic activity has been centered on uninhabited air vehicles, or UAVs. A small Marine UAV observation UAV was equipped with multiple winglets to evaluate potential performance boosts. Present efforts are focused on the design and wind tunnel testing of high altitude, long endurance UAV powered by solar cells. The project is in support of a Small Business Initiative, an example of the continuing interaction of AARL staff with industry.