Abstract
We introduce a novel method for measuring the properties of consolidating wood fibre network during filtration of liquid-fibre suspension. The device consists of a hand-sheet mould equipped with a pulsed ultrasound-Doppler anemometer for measuring the local time-dependent velocity field of the fibre phase during vertical filtration. Simultaneously, the total flux of the suspension and fluid pressure loss through the filtrated fibre layer are measured. Based on this experimental information other relevant flow quantities can be computed. We thus find the space-time evolution of velocity, volume fraction and pressure (stress) fields separately for the fluid phase and for the fibre phase. This method allows us to experimentally study the details of the consolidation process in dynamic conditions. The device can be applied as an advanced laboratory test instrument for measuring relevant physical fibre network properties. As a result we present, e.g., the measured local stress-strain history of the consolidating fibre layer during a filtration experiment.
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