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The Surface Pressure Response of a NACA 0015 Airfoil Immersed in Grid TurbulenceTwo grids have been developed for the Virginia Tech 6 ft x 6 ft Stability wind tunnel for the purpose of generating homogeneous isotropic turbulent flows for the study of unsteady airfoil response. The first, a square bi-planar grid with a 12" mesh size and an open area ratio of 69.4%, was mounted in the wind tunnel contraction. The second grid, a metal weave with a 1.2 in. mesh size and an open area ratio of 68.2% was mounted in the tunnel test section. Detailed statistical and spectral measurements of the turbulence generated by the two grids are presented for wind tunnel free stream speeds of 10, 20, 30 and 40 m/s. These measurements show the flows to be closely homogeneous and isotropic. Both grids produce flows with a turbulence intensity of about 4% at the location planned for the airfoil leading edge. Turbulence produced by the large grid has an integral scale of some 3.2 inches here. Turbulence produced by the small grid is an order of magnitude smaller. For wavenumbers below the upper limit of the inertial subrange, the spectra and correlations measured with both grids at all speeds can be represented using the von Karman interpolation formula with a single velocity and length scale. The spectra maybe accurately represented over the entire wavenumber range by a modification of the von Karman interpolation formula that includes the effects of dissipation. These models are most accurate at the higher speeds (30 and 40 m/s).
Document ID
20010000325
Acquisition Source
Langley Research Center
Document Type
Other
Authors
Bereketab, Semere (Virginia Polytechnic Inst. and State Univ. Blacksburg, VA United States)
Wang, Hong-Wei (Virginia Polytechnic Inst. and State Univ. Blacksburg, VA United States)
Mish, Patrick (Virginia Polytechnic Inst. and State Univ. Blacksburg, VA United States)
Devenport, William J. (Virginia Polytechnic Inst. and State Univ. Blacksburg, VA United States)
Date Acquired
September 7, 2013
Publication Date
November 1, 2000
Subject Category
Aerodynamics
Funding Number(s)
CONTRACT_GRANT: NAG1-1942
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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