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An experimental study of the turbulent mixing layer in concentrated fiber suspensions.

Julia Claesson (Institutionen för kemi- och bioteknik, Kemisk apparatteknik) ; Tomas Wikström ; Anders Rasmuson (Institutionen för kemi- och bioteknik, Kemisk apparatteknik)
Nordic Pulp & Paper Research Journal (0283-2631). Vol. 27 (2012), 5, p. 940-946.
[Artikel, refereegranskad vetenskaplig]

Turbulence structures in a free mixing layer after a backward-facing step were studied in concentrated pulp suspensions (0.5-3% by weight) using Laser Doppler Anemometry (LDA) at two predetermined average inflow velocities (0.9 and 1.8 m/s). Both average and fluctuating velocities were investigated and the findings were compared with measurements in water. The experimental findings show that both the average velocities and the RMS velocities in the mixing layer decreased with an increase in concentration. Furthermore, by analyzing the energy spectra at the center of the mixing layer, it was possible to extract the inertial sub-range of pulp suspensions with a concentration of 0.5% at the lower inflow velocity and in suspensions up to a concentration of 1% at the higher inflow velocity. At higher concentrations the turbulence was damped by the fiber network and no turbulence structures could be extracted. The energy content at lower frequencies was higher in the pulp suspensions than in the experiments in pure water.

Nyckelord: Fiber suspension; Turbulence; Mixing layer; LDA

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Denna post skapades 2013-01-07. Senast ändrad 2015-12-17.
CPL Pubid: 169421


Institutioner (Chalmers)

Institutionen för kemi- och bioteknik, Kemisk apparatteknik (2005-2014)



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Experimental and numerical studies of the flow of pulp suspensions