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Wind
Tunnel Specifications
|
Characteristics |
|
Test Section Size |
7 ft. by 10 ft. |
|
Wind Speed |
0 mph to 200 mph |
|
Mach Number Range |
0 to 0.25 |
|
External Balance |
6-component |
|
Sting Mount |
6-component Internal Balance |
|
|
|
Wind Tunnel |
|
Total Circuit Length
(at Centerline) |
396 ft. |
|
Maximum Diameter (in
Settling Chamber) |
30 ft. |
|
Cross-Sectional Shape
(Test Section) |
Octagonal |
|
(Diffuser Exit to Contraction Entrance) |
Circular |
|
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|
Test Section |
|
Cross-sectional Shape |
Octagonal |
|
Height |
7 ft. |
|
Width |
10 ft. |
|
Length |
12 ft. |
|
|
|
Contraction Section |
|
Cross-sectional Shape |
Transitions from Circular to Octagonal |
|
Contraction Ratio |
10.4 to 1 |
|
Contraction Length |
30 ft. |
|
|
|
Diffuser |
|
Location |
Immediately Downstream of Test Section |
|
Length |
46.5 ft. |
|
Horizontal Expansion Angle |
1.43 º |
|
Vertical Expansion Angle |
3.38 º |
|
|
|
Power Section |
|
Propeller Type |
4-blade Curtiss Electric |
|
Propeller Diameter |
12.5 ft. |
|
Electric Motor Rating |
900 RPM / 1250KVA |
|
Dynamic Pressure Range from |
0 to 100 lbs./ft.2 |
|
Propeller Blade
Pitch Angle Positioning |
|
|
Time to Set Test Section Dynamic Pressure |
Approximately 60 seconds |
|
|
|
External Balance |
|
Pitch Range |
-35 º to +35 º |
|
Yaw Range |
-120 º to +190 º |
|
Pitch and Yaw Accuracy |
± 0.05 º |
|
Pitch and Yaw Resolution |
0.01 º |
|
Lift Force Range |
-1000 lbs. to +3000 lbs. |
|
Drag Force Range |
-1000 lbs. to +1000 lbs. |
|
Side Force Range |
-1000 lbs. to +1000 lbs. |
|
Force Accuracy |
± 0.10 lb. or 0.1% of Applied
Load |
|
Force Resolution |
0.01 lb. |
|
Pitching Moment Range |
-2000 ft-lbs. to +2000 ft-lbs. |
|
Yawing Moment Range |
-1000 ft-lbs. to +1000 ft-lbs. |
|
Rolling Moment Range |
-2000 ft-lbs. to +2000 ft-lbs. |
|
Moment Accuracy |
± 0.10 ft-lb. or 0.1% of Applied
Load |
|
Moment Resolution |
0.01 ft-lb. |
|
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|
Internal Balances |
|
Task Mark X |
|
Diameter |
1.25 in. |
|
N1 |
100 lbs. |
|
N2 |
100 lbs. |
|
S1 |
50 lbs. |
|
S2 |
50 lbs. |
|
Axial Force |
60 lbs. |
|
Rolling Moment |
120 in-lbs. |
|
Pitching Moment |
425 in-lbs. |
|
Yawing Moment |
262.5 in-lbs. |
|
|
|
Task Mark XIII |
|
Diameter |
1.25 in. |
|
N1 |
500 lbs. |
|
N2 |
500 lbs. |
|
S1 |
500 lbs. |
|
S2 |
500 lbs. |
|
Axial Force |
150 lbs. |
|
Rolling Moment |
800 in-lbs. |
|
Pitching Moment |
2625 in-lbs. |
|
Yawing Moment |
2125 in-lbs. |
|
|
|
NASA 711-A |
|
Diameter |
1.75 in. |
|
Normal Force |
500 lbs. |
|
Side Force |
350 lbs. |
|
Axial Force |
500 lbs. |
|
Rolling Moment |
720 in-lbs. |
|
Pitching Moment |
4,200 in-lbs. |
|
Yawing Moment |
2,100 in-lbs. |
|
|
|
Air Quality Improvement Techniques |
|
→ Turning Vanes Installed at
each Corner of Circuit |
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→ Single Screen Located at Settling Chamber Entrance |
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→ Double Screen Upstream of Contraction Section to
Improve Dynamic Pressure |
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Uniformity and Reduce Flow
Turbulence Level |
|
→ Propeller Blade Tips Inset into the Tunnel Wall to
Minimize Interference Effects |
|
→ Automatic Motor Control Unit Synchronizes Speed in
10 sec. from Motor Start |
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Wind
Tunnel Performance Characteristics
Testing Regime
With the test section empty, the Texas A&M
Low Speed Wind Tunnel is capable of producing wind
velocities up to 290 feet per second at approximately
atmospheric static pressure. This corresponds to a test
dynamic pressure q, of 100 pounds per square foot in
accordance with the relationship:
q = ½*ρ*V2
Where:
ρ = air density, slugs per cubic foot
V = air velocity, feet per second
The maximum test Reynolds number, Re, is 1.844 × 106 per foot at
standard conditions where Reynolds number is defined by:
Re = ρ*V*d/µ
Where:
d = characteristic dimension, feet
µ = absolute viscosity of air, pounds seconds per square foot
Where "standard conditions" are defined as:
|
Temperature |
59° F |
|
Pressure |
2116.2 lb./ft2 |
|
Density |
0.002378 slug/ft3 |
|
Viscosity |
0.374 × 10^-6 slug/ft-sec. |
Flow Quality
Flow quality in the test section was
evaluated at dynamic pressures of 30, 50, 80, and 100 pounds
per square foot. Representative results of this calibration
are as follows:
|
Dynamic Pressure Variation |
±0.4% |
|
Flow Angularity |
±0.25° |
|
Static Pressure Gradient 0 |
0 |
|
Turbulence Factor |
1.10 |
|
Entry Boundary Layer Thickness |
1.5 inches |
|
Exit Boundary Layer Thickness |
3.5 inches |
Variation of dynamic pressure in an empty test section.
Velocity Measurement and Control
Tunnel flow is actually controlled and measured in terms of dynamic
pressure, q, rather than directly in terms of velocity. Test
section dynamic pressure is determined by a Druck pressure
transducer, which indicates tunnel q in pounds per square
foot. Static pressures are sensed by piezometer rings and
carried to the transducer through pressure tubing. The high
pressure piezometer ring is located in the settling chamber
and the low pressure ring is just upstream of the test
section entrance. The dynamic pressure resolution is ±.05
pounds per square foot.
Dynamic pressure is controlled by varying the propeller blade pitch angle
and is infinitely variable between zero and 100 pounds per
square foot. Except for very low dynamic pressures (q<1),
tunnel q setting can generally be achieved and held steady
in less than one minute from start.
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Technical
Services
In addition to typical testing services, the
wind tunnel offers three other areas of service:
An added
advantage of a university-connected wind tunnel is the ready
access to a human resource pool of technical expertise.
Day-to-day informal information exchange is the norm. Teams
of technical experts from varying disciplines can be formed
to solve a wide variety of problems using the wind tunnel
and other facilities as data gathering tools. For example, a
major wind engineering study might require specialists in
aeronautical engineering, structural analysis, architecture,
civil engineering, environmental design, mechanical
engineering and computer sciences. Because the University is
a non-profit organization, additional charges for technical
assistance are nominal and include only labor and overhead
costs.
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A full range of
wind tunnel model fabrication services is offered at the wind
tunnel. Complete design by experienced model engineers,
fabrication from customer supplied drawings, instrumentation
of customer models, or just minor last minute modifications
are among the services available.
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The location and
self-containment of the Texas A&M Wind Tunnel allow complete
security control for tests involving proprietary
information. Any degree of access limitation may be applied
as the customer dictates and security guards could be made
available if required by the security level. Charges for
security levels besides the standard proprietary information
will apply and can be quoted as needed. For classified
tests, the facility will have to obtain a site and personnel
clearances. This can be done in a per project basis and
costs vary depending on the level required. Sufficient
advance notice is required to arrange and complete the
process.
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Wind Tunnel
Diagrams
Diagram of Entire Wind Tunnel Circuit:
Click on Picture to Enlarge
Diagram of Wind Tunnel Test Section:
Click on Picture to Enlarge
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Oran W. Nicks Low Speed Wind
Tunnel
Texas A&M University
1775 George Bush Drive West,
College Station, TX 77845
Phone: 979.845.1028
Fax: 979.845.8191
Email:
information@wind.tamu.edu |
