Statistical analysis of turbulence by single-exposure speckle photography

Nikita A. Fomin; Evgenii F. Nogotov

doi:10.1117/12.279747

21 November 1997 Statistical analysis of turbulence by single-exposure speckle photography

Nikita A. Fomin, Evgenii F. Nogotov

Proceedings Volume 3172, Optical Technology in Fluid, Thermal, and Combustion Flow III; (1997) https://doi.org/10.1117/12.279747
Event: Optical Science, Engineering and Instrumentation '97, 1997, San Diego, CA, United States

Abstract

A new line-of-sight technique based on single exposure speckle photography is described that allows to measure the temperature fluctuations as well as the degree and direction of anisotropy of turbulence in a turbulent flow. To perform quantitative specklegram evaluations, a direct numerical simulation of the light tracing trough the turbulence is performed. Under assumption of geometrical optics the rays paths through the 3D turbulent field are computed from the ray equation. The 3D field of the index of refraction is prescribed on a numerical grid using data of direct numerical simulation of turbulent shear flows. As a result, the evaluation procedure of the 3D correlation function of turbulence reconstruction using 2D speckle photography data was developed and tested. An extension of the technique into a streak mode is described and an example of temporal evolution of turbulence in non-steady flow is presented.

Citation Download Citation

Nikita A. Fomin and Evgenii F. Nogotov "Statistical analysis of turbulence by single-exposure speckle photography", Proc. SPIE 3172, Optical Technology in Fluid, Thermal, and Combustion Flow III, (21 November 1997); https://doi.org/10.1117/12.279747

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