Fibre orientation measurements near a headbox wall

Abstract Experimental results on the fibre orientation in a laboratory scale headbox are reported. Images containing fibres in approximately 1 mm thick slices parallel to the wall were captured at different wall distances. A steerable filter was used to determine the orientation of bleached and unbeaten birch fibres, suspended in water, at different distances from one of the inclined walls of the headbox contraction. Due to optical limitations only dilute suspensions were studied. It is shown that the fibre orientation distribution varies with the distance from the wall. Sufficiently far upstream in the headbox a more anisotropic distribution is found closer to the wall.