Turbulence Intensity Study at Inlet of 80- by 120-Foot Wind Tunnel Caused by Upwind Blockage
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Date
2014-03-26
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Abstract
The National Full-Scale Aerodynamics Complex 80- by 120-Foot Wind Tunnel (80 x 120) at NASA Ames Research Center has operated as the world’s largest wind tunnel since the facility’s inception. Because the 80 x 120 inlet draws in air from the environment, precautions were taken during its design to reduce the effects of turbulence from ambient air by including inlet guide vanes, splitters, and screens. The effect of upwind buildings is unknown, and with the construction of a new Google building complex approximately 1200 feet upwind from the 80 x 120 inlet, it is necessary to investigate the consequences of such structures. A 1/50th-scale model of the 80 x 120 was tested to provide quantitative measurements for the increase in turbulence caused by a generic two-dimensional blockage located directly in front of the inlet. Tests were conducted at various blockage distances ahead of the inlet to identify when the effects of such an obstruction were no longer detected by a probe mounted at the centerline of the inlet. The resulting method necessitated splitting each two-minute data point into ten-second segments for analysis. Using this method, turbulence measurements showed better repeatability and indicated a negligible increase in 80 x 120 inlet turbulence for a building height of 50 feet located more than 1000 feet upwind during quiescent atmospheric conditions. Because the Google complex falls outside of that limit, NASA is confident that the construction will have little effect on the fidelity of the full-scale 80 x 120 during quiescent atmospheric conditions. The two-dimensional blockage measurements were part of a larger study to provide data on the 80 x 120 turbulence from specific upwind architecture including current buildings and the Google complex under both quiescent atmospheric conditions and non-zero atmospheric wind.
Description
Engineering: 3rd Place (The Ohio State University Denman Undergraduate Research Forum)
Keywords
Aerodynamics, Wind Tunnel, Aerospace Engineering, NASA, Google