The Flow Field Analysis Of The Rotor And Screen Cylinder Of The Inflow Screen Based On CFD

With the domestic continuous rise of the paper product quality requirements, the paper industry has a higher demand for pulp screening device. And for the rapid development of FLUENT, Computational Fluid Dynamics (CFD) has been in a variety of areas of rapid development and wide application. In paper industry, use CFD to guide the design of pulp screening equipment has become an important research direction.In order to improve the performance of pulp screening equipment, the study of the flow field of pulp screening process has been done. The impact of rotor blade and different geometrical parameters of the screen cylinder on screening process is explored. At first, the paper analyzes the structure of the screening equipment. Combine with the analysis features of FLUENT, the model is simplified. And then use AutoCAD software the two-dimensional models of the rotor blade and screen cylinder slot are created. And they are meshed by the powerful meshing of GAMBIT software. Finally the FLUENT6.3is used to value simulation the models. The flow field of the rotor rotating in the pulp and paper pulp coming into the sieve slit are got. And the detailed flow field analysis has been done.In this paper, through changing the shape and structure of the rotor blade, two improved blades are obtained. With the aid of the calculation of the flow field by the same conditions, the corresponding pressure distributions are got. Especially on the circumference of the screen frame where the pressure varies, that is, the rotor has an effect on the screen cylinder. And the size and region of the negative pressure represent the cleaning capability of the rotor. The cleaning capability more powerful the screen cylinder is more difficult to plug. Compared to the pressure field of the traditional blade, an ideal blade structure is acquired. The new blade has stronger cleaning capacity and is not easy to make the screen cylinder plug. The rotor blade airfoil has been optimized. Moreover, the influence rules of the linear velocity of rotor on pressure distribution are analyzed. The conclusion that the cleaning capability of rotor enhancement with the increase of the linear velocity. The energy-saving feature of the new rotor is proved.Combining with the rotor flow field analysis, the pulp flowing through the slot is simulated by turbulence model. The condition of vortex is looked into by the velocity vector drawing. The vortex formed by the wedge shape of bars basically makes the motion direction of the pulp fiber easier into the gap entrance. Besides, the flow fields of different wedge angles and different gaps have been calculated. The influence laws of bars wedge angle and gap width on screening are obtained by contrasting formed vortexes. The wedge angle is bigger. The vibration is more violent. And the long fiber output is higher. But the screening efficiency is lower. The gap which is too small will produce a higher pressure drop impacting production capacity in the sieve. The gap which is too large will produce too much backflow vortexes. They have effect on the screening quality.The specific impact of different parameters on the flow field has been summarized by aid of compute, analysis and contrast of flow fields. So they can be used to guide the design. It can make the structure of the screening equipment more conducive to the flow of paper pulp and the pulp screening. The efficiency and quality of screening can be improved. The wear and power consumption should be reduced. Overall, flow field analysis provides an effective means and theoretical guidance for the pulp screening device to optimize the design.