垂直螺旋输送机气固两相流的试验及数值模拟

Experiment and numerical simulation of gas-solid two-phase flow in vertical screw conveyor

在试验的基础上,采用欧拉-欧拉双流体模型对垂直螺旋输送机气固两相流动进行了数值模拟,分析了输送过程中的颗粒速度、混合相压力、颗粒体积分数、颗粒填充率和颗粒拟温度的分布。结果表明:颗粒轴向速度受进口和出口影响较大,本文根据轴向速度的分布,将流场分为进口影响区,稳定输送区,出口影响区。在稳定输送区内,颗粒总速度在管壁处较大,由于间隙的存在,颗粒轴向速度在靠近管壁处较小,最大值仅出现在叶片外缘处。混合相压力随着高度的增加而增大,在出口处略大于大气压。随着转速的增加,颗粒填充率减小,颗粒逐渐聚集在管壁和叶片外缘处,单个螺距内且呈V形分布。叶片上的颗粒拟温度沿径向自内向外逐渐增大,靠近管壁处的颗粒拟温度大于流道中的颗粒拟温度,可用颗粒拟温度来表示叶片磨损情况。

On the basis of experiment, Eulerian two-phase model was used to consider the velocity of particles, pressure of mixed phase, volume fraction and filling ratio of particles, and granular temperature distribution in vertical screw conveyor. The results showed that the axial velocity of particles was influenced by the inlet and outlet. Based on the distribution of axial velocity of particles, the vertical screw conveyor consists of inlet-influenced zone, stable transport zone and the outlet-influenced zone. In the stable transport zone, the total speed of the particles was higher at the tube wall, but because of the gap between the screw blade and the tube wall, the axial velocity was lower at the tube wall, and the maximum value appears only in the outer edge of the blade. The pressure of the mixed phase increases with the increase of the height, and was slightly higher than atmospheric pressure at the outlet. The particle filling ratio decreases with the increasing of the rotational speed, and the particles gradually gathered in the tube wall and the outer edge of the blade, which was with U distribution. The granular temperature on the blade increases gradually from the center to the edge in radial direction,and was higher near the tube wall than that in the flow channel, and it can represent the wear of the blade.