Simulation Research Of Fluid In Headbox With Roller And Shell

Headbox is the critical component of the paper machine.It is also the key hub for pulp flow and sheet forming and growing fast. At present rectifier roll headbox is widely used in the paper machine with low speed. Large transverse flow is generated when pulp flow through the rectifier roll, which cause the pulp flow unstabling. Especially when the cloth paste has dilution water control device. Large transverse flow is generated when fixed point dilution water and pulp flow through the rectifier roll, will greatly decrease the effectiveness of dilution water. The dilution water flow hydraulic slurry box is used in high speed paper machine, by the pulp distributing branch pipe joining dilution water to adjust the pulp concentration to control paper cross-machine quantitative. Homogenate device is turbulence generator, which produce high strength micro turbulent and prevent pulp from flocculation, homogenate device structure is fixed, can not be changed and adjusted when paper and papermaking performance requirements change.This article aims at the headbox with roller and shell, by adjusting the grooved roller speed and changing the structure of flow deflector on grooved roller to overcome disadvantages of rectifier roll headbox and improve the evenness of sheet, reduce deviation of basis weight in cross direction of sheet and homogenate device can be adjusted to meet from low to high speed of paper machine and different papermaking performance requirements. This article aims at the mathematical model of headbox with roller and shell, using simulation analysis software as ANSYS and fluent. The grooved roller structure statics and modal analysis and the fluid flow by different flow velocity and grooved roller speed has carried on the simulation research. By changing the size of flow deflector for fluid flow simulation research. By changing the position size and structure size of mixing chamber of headbox with roller and shell to study the fluid flow. The research focused on distribution of turbulence in the fluid and optimize the structure design parameters. The specific research contents and results are as follows:For grooved roller of the headbox with roller and shell, by reference to rectifier roll headbox structure size and turbulence generator size of hydraulic headbox, the initial structure size of the grooved roller and the mathematical model of the grooved roller is builded, through ANSYS WORKBENCH the structure statics analysis and modal analysis are carried on, preliminarily get the flow channel height by 30mm and safe grooved roller speed range.Based on the headbox with roller and shell internal flow field. By reference to the related structure size of rectifier roll headbox and flow channel height is obtained by fluid mechanics theory to establish mathematical model, analysis and comparison the numerical simulation results from the flow of headbox under different inlet flow velocity and grooved roller speed, preliminarily get the flow channel of headbox width size range for 10～16mm. Through the research of the inlet flow velocity and grooved roller speed difference and for the inlet flow velocity to 0.6m·s-1, grooved roller speed to 120rad·s-1 and 200rad·s-1 in flow channel by 10～15mm is appropriate. For flow channel by 25mm the inlet flow velocity to 0.6m·s-1 and grooved roller speed to 200rad·s-1 is appropriate.This article studies the flow deflector wall structure of headbox with roller and shell. The structural optimization and simulation experiment of the flow deflector wall were carried on research. The structure of flow deflector wall are optimized as follows:cords is alternate distribution on both sides of flow deflector wall, on both sides of flow deflector wall between every two adjacent cords, the centerline angle of cords is 0.5°, on the same side of flow deflector wall between adjacent two cords, the centerline angle of cords is 1°, cords is 23mm long, cross section of cords is triangle or polygon. With the increase of flow channel width, the fluid turbulence intensity decreases under the same structure of flow deflector wall, so it is needed to change the structure of the cords on the flow deflector wall and significant increase the grooved roller speed.This article studies the mixing chamber structure of headbox with roller and shell. The structural optimization and simulation experiment were carried on and optimization of mixing chamber structure by 10mm flow channel is:mixing chamber along the paper machine direction is 200mm long, vertical height of 400mm, mixing chamber entrance is 200mm high, along the paper machine direction mixing chamber outlet is 100mm long, above chamfer to 30°, below is 60°, mixing chamber shell side is tangent to headbox shell, the tangency point on the side of headbox shell which away from the paper machine direction.Based on comprehensive numerical simulation of fluid flow in headbox with roller and shell, the results has an important guiding significance to the further structure optimization design of headbox with roller and shell.