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A reflection-type oil-film skin-friction meterUnlike many conventional methods of measuring skin-friction, the oil-film method is absolute in nature, requires no calibration, and, in principle, can be universally applied. In all existing forms of the meter, however, interferometry is used to make measurements of the oil film. Here, the technique has been simplified by completely eliminating interferometry. This has been achieved by making direct and dynamic measurements of the oil-film slope by directing a reflected beam of light off the top of the oil film to a small position sensing photodiode. The reflection method has been verified in incompressible flat plate turbulent boundary-layers. The standard of deviation of the measurements is about 10 percent of the mean. The present version of the meter is compact and simple.
Document ID
19910070984
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Bandyopadhyay, P. R.
(NASA Langley Research Center Hampton, VA, United States)
Weinstein, L. M.
(NASA Langley Research Center Hampton, VA, United States)
Date Acquired
August 14, 2013
Publication Date
September 1, 1991
Publication Information
Publication: Experiments in Fluids
Volume: 11
Issue: 5 Se
ISSN: 0723-4864
Subject Category
Instrumentation And Photography
Accession Number
91A55607
Funding Number(s)
CONTRACT_GRANT: NAS1-18235
CONTRACT_GRANT: NAS1-18599
Distribution Limits
Public
Copyright
Other

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