Measurements of admixture concentration fluctuations in a turbulent shear flow using an averaged Talbot image |
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Authors: | M V Doroshko P P Khramtsov O G Penyazkov I A Shikh |
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Institution: | (1) A. V. Luikov Heat and Mass Transfer Institute, P. Brovka str., 15, 220072 Minsk, Belarus |
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Abstract: | The present study is concerned with adopting of a Talbot effect-based technique for analyzing flows with random phase inhomogeneities.
It is shown that this method is a powerful tool for diagnostics of turbulent flows. The potential of the technique is illustrated
by measuring mean and fluctuating values of admixture concentration of two-dimensional turbulent helium jet issuing into the
ambient air. Averaged air and helium concentrations throughout the flow field are determined using local light refraction
measurements with a high spatial resolution from a long-exposed Talbot image of the jet. The analysis of light intensity distributions
in light spots of a Talbot-image shows that the jet turbulence is inhomogeneous and anisotropic. Quantitative information
on rms fluctuations of concentration gradients throughout the flow field is obtained from local photometric measurements at
the Talbot light spots. |
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