Experimental And Numerical Modeling Study On Fluidynamics In Stirred Tanks

Though stirred vessels agitated are very common in the chemical and allied industries, the theory of mixing and the design mixing equipment methods are not developed well up to now, the methods of scale-up for agitation equipment rely on correlation among dimensionless group of parameters , empirical methods is still the main tools for design and scale-up industry process. To meet the purpose for optimal design and scale-up and fully understand the processes occurring in stirred vessels, there are needs for careful experimental measurement and mathematical models to measure and describe the characteristics of flow in stirred vessel. This study is preliminary work along this line.In this study, the turbulence flow characteristics in a stirred tank for single-impeller and dual-impeller have been investigated. The mean and fluctuating velocities at different locations have been measured by using three-dimension Particle Dynamic Analyzer (PDA). Based on the measured result, the overall flow patterns in stirred tank are obtained, the effect of impeller diameter, impeller tip angle, the impeller clearance and the impeller periodic rotation on flow pattern and turbulence intensities have been also studied.Experimental studies on solid-liquid two phase flow in stirred tank have been carried out , the mean velocities of two phase have been measured by using three-dimension PDA. The results show that the particle existence enhances or deduces the velocities and turbulence intensities of fluid phase in deferent region in stirred tank.According to the flow characteristics in stirred tank, the numerical procedure and computational code have been successfully developed on the basis of the k- e turbulence model, and are used to simulate the flow field in single-impeller and dual-impeller stirred tank systems, the effect of boundary conditions and value of k- z model parameters on simulation results are also studied. The predicted results are in good agreement with those obtained by PDA measurements made in this dissertation. Based on the above stated computer codes, the rotating coordinate, which is fixed with rotating shaft, has been introduced to simulate the flow field of turbine blade stirred tank, the predicted results agree better with experimental data. Compared with the predicted results given by "black box"method, the results given by rotating coordinate...