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Proceedings Paper

Statistical assessment of optical phase fluctuations through turbulent mixing layers
Author(s): Patrick J. Gardner; Michael C. Roggemann; Byron M. Welsh; Rodney D. Bowersox
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Paper Abstract

A lateral shearing interferometer is used to measure the slope of perturbed wavefronts after propagating through turbulent shear flows. This provides a two-dimensional flow visualization technique which is nonintrusive. The slope measurements are used to reconstruct the phase of the turbulence-corrupted wave front. Experiments were performed on a plane shear mixing layer of helium and nitrogen gas at fixed velocities, for five locations in the flow development. The two gases, having a density ratio of approximately seven, provide an effective means of simulating compressible shear layers. Statistical autocorrelation functions and structure functions are computed on the reconstructed phase maps. The autocorrelation function results indicate that the turbulence-induced phase fluctuations are not wide-sense stationary. The structure functions exhibit statistical homogeneity, indicating the phase fluctuation are stationary in first increments. However, the turbulence-corrupted phase is not isotropic. A five-thirds power law is shown to fit one-dimensional, orthogonal slices of the structure function, with scaling coefficients related to the location in the flow.

Paper Details

Date Published: 29 September 1995
PDF: 15 pages
Proc. SPIE 2546, Optical Techniques in Fluid, Thermal, and Combustion Flow, (29 September 1995); doi: 10.1117/12.221523
Show Author Affiliations
Patrick J. Gardner, Air Force Institute of Technology (United States)
Michael C. Roggemann, Air Force Institute of Technology (United States)
Byron M. Welsh, Air Force Institute of Technology (United States)
Rodney D. Bowersox, Air Force Institute of Technology (United States)

Published in SPIE Proceedings Vol. 2546:
Optical Techniques in Fluid, Thermal, and Combustion Flow
Soyoung Stephen Cha; James D. Trolinger, Editor(s)

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