3' X 2' Low Speed Wind Tunnel
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| Photograph of the 3' x 2' Low Speed Wind Tunnel |
The 3'x2' Low Speed Wind Tunnel is sited in the basement of Randolph hall. The facility has a test section 3' wide, 2' high and 20' long and can produce flow speeds from zero to 30m/s. Flow in the test section is very closely uniform and of low turbulence intensity (0.17%) making this an ideal research wind tunnel. Equipment associated with this wind tunnel includes a two-axis computer controlled traverse gear, sophisticated multi-sensor hot-wire manufacture, repair, calibration and measurement systems and a directly calibrated 7-hole yaw probe system.
This wind tunnel is used primarily by graduate and undergraduate students involved in sponsored research projects in the area of experimental fluid mechanics. This work, directed by
Dr. William Devenport, is described in more detail on our Turbulence Research pages. Recent work in this facility includes experiments on wakes, tip vortices, vortex control and airfoil aerodynamics.
As an example, the following picture shows hot-wire measurements made in this facility in a cross section through the wake of a rectangular wing at angle of attack at a position 10 chordlengths downstream. The quantity plotted is turbulence kinetic energy. On the left, the wake is rolling up around the tip vortex, shed as an inevitable consequence of the generation of the lift. The stretching and straining of the rest of the wake in the velocity field of this vortex produces the complex turbulence structure visible here. This measurement, which includes data on all mean velocity, Reynolds stress and triple product components over the entire cross-section, was performed in only a few hours using our computer controlled traverse and hot-wire measurement system.
A sample flow visualization below, performed using a 45W Copper Vapor laser to illuminate helium filled soap bubbles injected into the flow, reveals the structure of the flow over the wing tip itself. The formation of the main tip vortex, and of a secondary vortex that causes the main vortex to spiral, are both visible. The laser is pulsed and thus individual bubbles produce multiple images in the photograph. Since the laser pulses occur at regular intervals, the distance between successive images can be used to estimate the local flow velocity.
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AOE Research
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