Technical Guide to the TAD-2 Wind Tunnel

4. Test Section

4.1 Dimensions

Test section of an octagonal shape is 2.5 meters high, 4 meters wide, and 5.5 meters long. The actual cross-section area is 9.5 m². This number is the largest in Ukraine. Test section is situated in Eiffel chamber 5.5 meters long, 6.5 meters wide, and 9.0 meters high. Eiffel chamber occupies second and third flours of TAD-1 and TAD-2 test sections building and its floor is leveled to the second flour of the building.

4.2 Construction

The test section has slotted walls. This ensures small enough upwash interference and blocking while testing high-lift configurations and permits testing of slightly larger models, as compared to opened and closed test sections. Wall panels are made of aluminum alloy profiles and mounted on three strong steel frames. In the lower wall a turntable is performed (2 meters in diameter) with circular (hole) perforation. The table is attached to 2.1 meters in diameter inner ring of a ball bearing with gear wheel, used as a driven gear of remotely controlled electric turn drive.
The height of the lower wall of the test section relative to the level of the second flour is 1.25 meters. To access tests section from control room a 1 by 1.5 meters hatch is performed, and from the opposite side another 2 by 1.5 meters hatch is made. The last is adjacent to hermetic gate and from the outer side of this a lifting work area is arranged for large-size heavy models handling.
Eiffel chamber is made of steel sheets with reinforcement elements and faced from outside with bricks. Its strength permits to withstand internal depression up to 6,500 Pa (equivalent test section velocity is 100 m/sec).
To enter Eiffel chamber during tunnel run an air lock is made at the control room side.

4.3 Test Conditions

A detailed upflow and dynamic pressure calibration of the test section were conducted using NAU six-hole probe rake, DISA ELECTRONICS hot-wire anemometer, spheres 100, 150, and 250 mm in diameter, control wing (295.1 mm chord, aspect ratio 5, G-365 profile). Investigation shows a turbulence intensity of 0.9% (sphere turbulence factor of 1.67), neglible upflow and crossflow.
As TAD-2 wind tunnel is situated in the open area, testing conditions are similar to ambient atmospheric ones. During the year temperature varies from minus 20 centigrade in winter to +35 centigrade in summer, and atmospheric pressure ranges 720...760 mm hg.