Investigation On Turbulent Flow Characteristics In A Solid-Liquid Stirred Tank

Solid-liquid mixing operation is very common in many industry processes, such as petroleum, chemical industry, metallurgy industry. The low viscosity fluid mixing depends on macro-eddy diffusion and liquid turbulence. Therefore, it is important to investigate the solid-liquid turbulence characteristics on industrial production.In this paper, the characteristics of solid-liquid two-phase flow will be studied in a stirred tank. At present, the prediction of the solid-liquid turbulence properties is mostly relying on simulations, such as the high concentration, the high viscosity solid liquid suspension. In general, the simulation software has some defects and could not be responded to the true flow field experiment. Therefore, the purpose of this task is to do some experiments to predict the solid-liquid turbulent flow in a stirred tank and provide experimental evidence. Then, simulations of the low-viscosity, low-density solid-liquid two-phase flow was carried out and then the results of simulations were compared with the PIV experiment. Experiments should be in a transparent plexiglass tank which the diameter is 220mm and measured with 2D-PIV. The solid volume fraction will be changed from 0.2%(φ) to 5%(φ). The results show that the magnitude of continuous phase characteristics will be changed by the increasing of solid particles concentration. Compared with single-phase flow, the liquid velocity, turbulence kinetic energy will be decreased in the impeller region during the solid concentration increased from 0.2% (φ) to 0.9%(φ). However, the dissipation rate of the turbulent kinetic energy will be continued to increase. In the near wall region, with the increasing of particle concentration, the overall liquid velocity will be decreased continuously. When the particle concentration increased from 0.2%(φ) to 0.9%(φ), the overall average trend of the liquid turbulent kinetic energy will be decreased, and then it will be increased when the concentration changes from 1%(φ) to 5%(φ).The solid-liquid simulations will be carried out under the same conditions in this experiment with CFX software. The liquid turbulence parameters and the experiment values are complex, because the turbulent kinetic energy values are in a good agreement under low concentration (0.2%(φ)-0.7%(φ)), it is different sharply under other conditions.