DEFINING THE FLOW FIELD OF AN OPEN-JET WIND TUNNEL

This investigation deals with mapping the velocities at successive cross-sectional planes in the test section of an open-jet wind tunnel. The instrumentation was chosen so that the total uncertainty on the calculated velocity would be less than 1% with a 95% confidence level. The jet was studied usi...

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Bibliographic Details
Main Authors: Poole, Donald B, Cromack, Duane E
Format: Report
Language:English
Subjects:
Aerodynamics
FLOW FIELDS
FLOW VISUALIZATION
Fluid Mechanics
JET FLOW
Test Facilities, Equipment and Methods
THEMIS PROJECT
TURBULENCE
VELOCITY
WIND TUNNELS
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Summary:This investigation deals with mapping the velocities at successive cross-sectional planes in the test section of an open-jet wind tunnel. The instrumentation was chosen so that the total uncertainty on the calculated velocity would be less than 1% with a 95% confidence level. The jet was studied using photography and a grid-and-tuft scheme, and it was determined that the same flow characteristics appear at both high and low flow rates. The best probable location for model testing was determined to be 1-1/4 ft. to 2-1/2 ft. away from the exit plane of the tunnel as indicated by the combined pressure measurements and the photographic studies. It was also noted that turbulent mixing occurred between the jet and the still air in the room. The turbulence had a tendency to move in toward the center of the jet at successive planes from the exit plane of the tunnel. The most drastic change in turbulent mixing occurred at a cross-section 3 ft. away from the exist plane. Recommendations for alterations to the facility are made for testing at or near the 3 ft. location. Subcontract no. N00014-68-A-0146-12.