Statistical assessment of optical phase fluctuations through turbulent mixing layers

Patrick J. Gardner; Michael C. Roggemann; Byron M. Welsh; Rodney D. Bowersox

doi:10.1117/12.221523

29 September 1995 Statistical assessment of optical phase fluctuations through turbulent mixing layers

Patrick J. Gardner, Michael C. Roggemann, Byron M. Welsh, Rodney D. Bowersox

Proceedings Volume 2546, Optical Techniques in Fluid, Thermal, and Combustion Flow; (1995) https://doi.org/10.1117/12.221523
Event: SPIE's 1995 International Symposium on Optical Science, Engineering, and Instrumentation, 1995, San Diego, CA, United States

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.

Citation Download Citation

Patrick J. Gardner, Michael C. Roggemann, Byron M. Welsh, and Rodney D. Bowersox "Statistical assessment of optical phase fluctuations through turbulent mixing layers", Proc. SPIE 2546, Optical Techniques in Fluid, Thermal, and Combustion Flow, (29 September 1995); https://doi.org/10.1117/12.221523

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