稀释水在布浆支管中的混合特性研究

Study on the Mixing Characteristics of Dilution Water in the Distribution Pipe of Hydraulic Headbox

稀释水调浓水力式流浆箱通过局部调节浆料浓度控制全幅横向定量偏差,采用Realizableκ-ε湍流模,利用数值模拟的方法研究稀释水在布浆支管内与浆流的混合与扩散特性,数值模拟结果与相关试验数据吻合良好;稀释水在浆流中的混合主要通过反向漩涡的逐渐扩散。在入射点近场,稀释水与浆流快速混合,当z/d>7后,混合参数M变化趋向平缓,这表明混合速度逐渐降低。在稀释水入射点的下游,距离入射点越远,射流扩散程度越高,混合效果越好;提高稀释水的入射速度,有利于提高混合效果。

Abstract： The method of adjusting the local concentration is taken by hydraulic headbox to control the basis weight in cross direction. In this paper, the turbulence model of Realizable K-ε was adopted to simulate the mixing of dilution water with stock. The results of simulation are consistent with that of experiment. Reverse vortex pair is the main form of dilution water diffuses in stock. The result shows dilution water and stock mix quickly in near field of jet point, but in the downstream, the mixing parameters （M） keeps comparatively steady when z 〉 7d. This illustrates the speed of mixing decreases gradually. In the downstream, the dilution get more even with distance increases. Increasing the incidence speed of dilution water is good for mixing effect.