Laser Doppler velocimetry studies on cryogenic fluids

Beresford, Glenn (1984) Laser Doppler velocimetry studies on cryogenic fluids. University of Southampton, Doctoral Thesis.

Record type: Thesis (Doctoral)

Abstract

The technique of Laser-Doppler velocimetry has been developed for the study of cryogenic fluids. The theory and use of the Laser-Doppler velocimeter is discussed, as is the associated equipment required. Measurements are presented for the vertical velocity components and temperature profiles in the laminar part of the vapour column flow above boiling liquid nitrogen. The mass fluxes within the vapour column are calculated from these measurements. The vapour flow consisted of a small turbulent region near the liquid surface, the rest of the column being laminar. The laminar region consisted of a thin, upward flowing boundary layer attached to the wall of the Dewar and a large, slow central core moving downwards. The thickness of the boundary layer is calculated from the velocity profiles and has been found to vary linearly with height. The height variations of the reduced wall and axial temperatures for the laminar region have been found to be exponential. Some measurements are presented for vertical velocity components in a liquid nitrogen pool in order to demonstrate the applicability of Laser-Doppler velocimetry to such a system. Cryogenic flow visualisation techniques are also discussed, and some illustrative results are presented.

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