THERMAL SCIENCE

International Scientific Journal

Jelena T. Ilić

,

Slavica S. Ristić

,

Milesa Ž Srećković

LASER DOPPLER VELOCIMETRY AND CONFINED FLOWS

ABSTRACT
Finding the mode, in which two component laser Doppler velocimetry can be applied to flows confined in cylindrical tubes or vessels, was the aim of this study. We have identified principle issues that influence the propagation of laser beams in laser Doppler velocimetry system, applied to flow confined in cylindrical tube. Among them, the most important are influences of fluid and wall refractive indices, wall thickness and internal radius ratio and beam intersection angle. In analysis of the degrees of these influences, we have applied mathematical model, based on geometrical optics. The separation of measurement volumes, that measure different velocity components, has been recognized as the main drawback. To overcome this, we propose a lens with dual focal length – primary focal length for the measurement of one velocity component and secondary focal length for the measurement of the other velocity component. We present here the procedure for calculating the optimal value of secondary focal length, depending on experimental set-up parameters. The mathematical simulation of the application of the dual focal length lens, for chosen cases presented here, confirmed the accuracy of the proposed procedure.
KEYWORDS
Laser Doppler velocimetry, confined flow, cylindrical tube, fluctuation, geometrical optics
PAPER SUBMITTED: 2016-07-20
PAPER REVISED: 2016-09-02
PAPER ACCEPTED: 2016-09-22
PUBLISHED ONLINE: 2016-11-06
DOI REFERENCE: https://doi.org/10.2298/TSCI160720278I
CITATION EXPORT: view in browser or download as text file
THERMAL SCIENCE YEAR 2017, VOLUME 21, ISSUE Supplement 3, PAGES [S825 - S836]
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Laser doppler velocimetry and confined flows

© 2024 Society of Thermal Engineers of Serbia. Published by the Vinča Institute of Nuclear Sciences, National Institute of the Republic of Serbia, Belgrade, Serbia. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International licence