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Abstract

Methods and apparatus to enhance paper and board forming qualities with insert tubes and/or a diffuser block in the paper forming machine headbox component which generates vorticity in the machine direction (MD) which is super imposed on the streamwise flow to generate a swirling or helical flow through the tubes of the diffuser block. Tubes of the diffuser block are designed such that the direction of the swirl or fluid rotation of the paper fiber stock may be controlled and the direction thereof is controlled in such a way to provide effective mixing, coalescence and merging of the jets of fluid emanating from the tubes into the converging section, i.e., nozzle chamber of the headbox. A specific flow inside the headbox distributes the fibers in an isotropic form, i.e., uniform in all directions, in the sheet substantially eliminating the MD preferential fiber orientation to produce an isotropic and uniform sheet. Cross-machine direction (CD) shear between the rows of jets that form at the outlet of the tubes inside the nozzle chamber of the headbox align paper fibers in the cross-machine direction.

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First Claim