The Streamwise Evolution of Hydrodynamic Quantities and Flexible Fiber Orientation in A Turbulent Contracting Flow with Multi-Jet Interaction Inlet Condition

Abstract:

The dynamic behavior of pulp fiber in turbulent extensional flow field with the multi-jet interacting inlet flow condition contains important information in the papermaking process. The detailed mean flow and turbulent quantities measurements with Laser Doppler Velocimetry (LDV) were performed to understand the fundamental hydrodynamics in this type of flow. The multi-jet interaction in the turbulent extensional flow field decayed significantly within one third of the nozzle length from the inlet. Also turbulent quantities significantly decreased in streamwise direction in the same region. The streamwise evolution of turbulent spectrums was obtained in frequency and wave number domain. The transformation of the frequency domain signal to the wave number domain was performed by Taylor's hypothesis. The fiber orientation dispersion in the dilute fiber suspension flow was visualized with the high speed imaging technique and the mean fiber orientation in this flow condition was estimated by newly developed image analysis technique.

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