Accession Number:

ADA324255

Title:

Wall Pressure Signatures of Organized Turbulent Motions.

Descriptive Note:

Final rept.,

Corporate Author:

CATHOLIC UNIV OF AMERICA WASHINGTON DC DEPT OF MECHANICAL ENGINEERING

Personal Author(s):

Report Date:

1997-04-25

Pagination or Media Count:

195.0

Abstract:

An extensive database of simultaneously obtained wall pressure and velocity measurements was acquired for a high Reynolds number, equilibrium turbulent flow. These data were obtained in both streamwise and spanwise measurement planes using an array of wall pressure transducers. Analyses of these data were performed to examine the spatial extent and convective features of turbulence producing structures. Several signal processing techniques were shown to extract detailed structural features of the turbulent motions. These techniques included digital band-pass filtering to discriminate between turbulent scales and a localized variance method for the detection of clusters of high frequency turbulent activity. Cross-spectral, cross-correlation, and conditional sampling methods applied to these data clearly show the dynamical relationships between coherent turbulent motions as well as their induced wall pressure signatures. Both pressure-velocity correlation results and conditionally averaged maps of the flow field sampled on peak wall pressure events, reveal a consistent correlation between large scale motions and near-wall, small scale turbulent production activity. The large scale vortical motions or shear layers extend across the turbulent boundary layer and exhibit Reynolds stress turbulent production characteristics. These findings are consistent with many of the proposed conceptual models of organized motions.

Subject Categories:

  • Fluid Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE