engleski

REYNOLDS NUMBER EFFECTS IN THE NEAR – WALL REGION OF TURBULENT FILM FLOWS

The aim of the work is analysis of performance of Reynolds numbers change on turbulence of liquid film flow near the wall of open channel. Experimental data on turbulent behaviour in the area close to the wall have been presented by use of high resonance LDA techniques, which allowed the determination of the Reynolds number range above which turbulence quantities scale on the inner variables. We started firsly with open channel where, by changing flow regimen we got certain values of RE number in range from 3000 up to 5000 which characterizes turbulent circulation. Velocities in the channel were measured from 0.04 mm up to film thickness of 5 mm and more. Using values of average and local velocities shear stress was calculated on the surface of wall tw as well as shear velocity ut . These experiments show that the velocity of flow has an important role in shaping of film layer on the surface.

Turbulent wall flows; film thickness; laser – Doppler anemometer

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