The Impact of Turbulence and Swirl on the Flow in the Tube Bank Part of a Paper Mill Headbox (submitted by US Department of Energy, 2004 Paper Summit, Spring Technical & International Environmental Conference, (including Papermakers; Process Control, Elec

This paper reports experimental investigation of the swirl flow generated by twisted fins inside a single tube in the tube bank part of a paper-making machine using a two-component laser-Doppler velocimeter (LDV). By controlling the flow of the pulp slurry leaving the headbox, fiber orientation within the slurry can be controlled. Axial vorticity (i.e. swirl) inside the headbox tubes is coupled with an automatic on-line control system to regulate the interaction between the turbulent flow and the fiber suspension. In initial studies investigating the characteristics of the swirl flow tapered fins with 0° and 180° twist, corresponding to the extreme cases of zero and maximum axial vorticity, are studied at a pipe-based Reynolds numbers of 7.5 × 104. The LDV system is used to measure radial profiles of the mean and rms fluctuations of the streamwise velocity component. The impact of swirl, introduced by twisted fins, on the turbulent wake will be compared and discussed relative to the straight fin. An initial implementation of the automatic on-line actuation system based on shape memory alloys will also be discussed. Proper fiber alignment increases the properties of stiffness and toughness in paper products, and eliminates variability in their physical properties. As a result, development of this technology will lead to fewer rejects, increased productivity, and significantly reduced costs for fiber, water, and energy for the pulp and paper industry.