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Proceedings Paper

Laser-Doppler anemometry based on the molecular dispersion in a hydrodynamic experiment
Author(s): M. Y. Kachalov; Leonid N. Preslenev; Dmitry V. Tigin
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Paper Abstract

One of the most important metrology problems is a problem of velocity measurement /1/. Laser Doppler anemometry permits to solve this problem by means of the non contact method. The essential advantage of this method is a high measurement accuracy and space localization. In the laser Doppler anemometry dispersion of optical energy on reasonably large particles is used. The applications of given method has essential restrictions, especially at a high enough velocities and considerable turbulence of the flow. In this case speeds of the particles does not correspond to the flow velocity. An other problem is that reasonably large particles disturb a flow structure. Therefore when the flow velocity is commensurable with the velocity of the acoustic wave or the turbulence of the flow is essential, the probability of measurements becomes questionable. To terminate these limitations the employment of the molecular dispersion phenomenon in the laser Doppler anemometer creation was offered. This method doesn't demand the existence of the dispersion particles in the flow. The dispersion centers are formed because of the thermal molecular displacement. The spectrum of the dispersed optical radiation has three frequency components. The first one comes into existence at the same wavelength with the probe optical radiation, but contain reasonably large number of molecules. Obviously, in the ideal medium without any optical impurities should be no dispersion of optical radiation, as the radiation dispersed by the various elementary volumes will be equal. However in any really existing medium an optical impurities are present, they are stipulated by the thermal chaotic movement.

Paper Details

Date Published: 24 September 1999
PDF: 5 pages
Proc. SPIE 3900, 3rd International Conference on Optical Information Processing, (24 September 1999); doi: 10.1117/12.364545
Show Author Affiliations
M. Y. Kachalov, St. Petersburg Univ. of Aerospace Instrumentation Engineering (Russia)
Leonid N. Preslenev, St. Petersburg Univ. of Aerospace Instrumentation Engineering (Russia)
Dmitry V. Tigin, St. Petersburg Univ. of Aerospace Instrumentation Engineering (Russia)

Published in SPIE Proceedings Vol. 3900:
3rd International Conference on Optical Information Processing
Yuri V. Gulyaev, Editor(s)

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