斜板浅层内液流运动特征研究

Study on the Motional Characteristics of the Liquid Flows inside the Thin Layer between Tilting Plates

采用固体粒子示踪法，观测记录了不同给料流量下，颗粒群中各单颗粒在斜板浅层单元内运动轨迹、速度和区间流态。在设定的斜板单元结构参数下，导出了浅层沉降保持层流的雷诺数判据；修正了过渡区长度的原有计算公式。根据研究，解释了按原有理论计算的斜板沉降能力远高于实际值的原因，指出界定颗粒粒径取决于板间最大流速。

The solid particle tracing method was used for observing and recording the motion loci,velocities and the distribution forms of the various single particles inside the thin layer between two tilting plates under different feeding rates.The criterion of Renolds Number for maintaining the laminar flow settling in this thin layer and the original calculatoin formula for the intermediate zone length was modified under the specified structural parameters of the lamella unit.Based on the research results,the reason that the calculated capacity of the lamella thickener according to the existing theory is much higher than the real value is explained and it is claimed that the particle size limit of overflow depends upon the maximum flow velocity between plates,whose value is recommended to be five times the average one for use in the engineering calculations.