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Accession Number
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N20120012007
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Title
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Determining Correlation and Coherence Lengths in Turbulent Boundary Layer Flight Data.
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Publication Date
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Mar 2012
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Media Count
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17p
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Personal Author
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D. Palumbo
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Abstract
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Wall pressure data acquired during flight tests at several flight conditions are analysed and the correlation and coherence lengths of the data reported. It is found that the correlation and coherence lengths are influenced by the origin of the structure producing the pressure and the frequency bandwidth over which the analyses are performed. It is shown how the frequency bandwidth biases the correlation length and how the convection of the pressure field might reduce the coherence measured between sensors. A convected form of the cross correlation and cross spectrum is introduced to compensate for the effects of convection. Coherence lengths measured in the streamwise direction appear much longer than expected. Coherent structures detected using the convected cross correlation do not exhibit an exponential coherent power decay.
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Keywords
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Bandwidth
Bias
Data correlation
Flight conditions
Flight tests
Frequencies
Pressure distribution
Turbulent boundary layer
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Source Agency
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National Aeronautics and Space Administration
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NTIS Subject Category
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51A - Aerodynamics
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Corporate Author
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National Aeronautics and Space Administration, Hampton, VA. Langley Research Center.
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Document Type
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Journal article
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Title Note
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N/A
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NTIS Issue Number
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1303
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Contract Number
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N/A
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