Actions for Some features of surface pressure fluctuations in turbulent boundary layers with zero and favorable pressure gradients

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Some features of surface pressure fluctuations in turbulent boundary layers with zero and favorable pressure gradients

Author
Mcgrath, B. E.
Published
Mar 1, 1987.
Physical Description
1 electronic document
Additional Creators
Simpson, R. L.
Online Version

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Unclassified, Unlimited, Publicly available.
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Summary
Measurements of surface pressure fluctuation spectra, coherence and convective wave speeds from zero and favorable pressure gradient turbulent boundary layers are reported for momentum Reynolds numbers from 3000 to 18,800. The acceleration parameter K is near 2 x 10 to the -7 power for the favorable pressure gradient flow. The outer variables, U sub e, tau sub w and delta sub 1 non-dimensionalize and collapse the spectra for the low to middle range of frequencies for most test cases. The grouping using the inner variable, U sub tau and gamma, collapse the spectra for the middle to high range of frequencies for all test cases. The value of p'/tau sub w was near 3.8 and 2.8 for the smallest values of d+ in the zero and favorable pressure gradient flows, respectively. The coherence exhibits a decay that is not exponential in some cases, but the Corcos similarity parameters omega Delta x/U sub c and omega Delta z/U sub c collapse the data for all test cases. The ratio of U sub c/U sub e increases with omega delta sub 1/U sub e up to omega delta sub 1/U sub e on the order of unity, where U sub c/U sub e becomes nearly constant. This was observed in the present results for both streamwise pressure gradient flows. The experimental results presented show good agreement with previous research.
Other Subject(s)
Collection
NASA Technical Reports Server (NTRS) Collection.
Note
Document ID: 19870008970.
Accession ID: 87N18403.
NASA-CR-4051.
NAS 1.26:4051.
Terms of Use and Reproduction
No Copyright.
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