Research Of The Numerical Simulation And Flocculation Efficiencies Of Taylor-Couette Flow

The fluid mechanics conditions of flocculation process is an important factor forflocculation. However, the theory of current velocity gradient can not fully explain themechanism of flocculation kinetics, such as grid flocculation pool. In addition, theory ofturbulent flow also only stay in the stage of qualitative description. Therefore, It is necessaryto study more the flow field characteristics of flocculation reaction process, and to proceed thequantitative analysis. In order to reveal the cause of flocculation reaction kinetics, and createmore favorable conditions of turbulent flow field, also promote the efficiency of reactions.Based on the FLUENT numerical simulation and the result of flocculation experiment,the paper researched the effect of hydraulic conditions on the flocculation efficiency.Theresults can be extended to find an effective way to optimize the design and operation, toimprove the efficiency of flocculation. The paper comes to conclusion as follows:（1）Based on FLUENT technology，the3d numerical simulation of Taylor-Couette flowwas performed, and the flocculation efficiencies were also obtained in the sameTaylor-Couette flow at the different inner cylinder rotational speeds. The flow fieldcharacteristics of Taylor-Couette flow field include velocity distribution, turbulent kineticenergy, turbulent intensity distribution, and available energy dissipation, through thenumerical simulation can be qualitative and quantitative analysis of the impact of theflocculation efficiency.（2）Through numerical simulation, the morphology, size distribution, direction andchange rule of the Taylor vortex in the in annular gap of Taylor-Couette reactor.（3） Flocculation experiment is designed, which includes orthogonal experiments andsingle factor experiment, in order to determine the best chemical conditions. At the same time,the floc morphological characteristics are researched by microscopic photography and imageanalysis.（4）In combination with the results of numerical simulation and flocculation experiments,make a reasonable explanation of the complex phenomenon in the process of flocculation, andverify the rationality of flow field characteristics as flocculation evaluation index.The results indicated that： The vortices of submicroscopic size were formed in theannulus gap as shown in the velocity vector map, and the velocity gradient inside the vorticeswas lower than outside vortices. When the inner cylinder speeds changed from10r/min to60r/min, and the turbulent kinetic energy was in the range of2.64E-05～0.00023m²Â·s^-2, andthe turbulent intensity was in the range of0.418%～1.17%, available energy dissipation ratewas in the range of6.57E-05～0.00189m²Â·s^-3, the flocculation efficiencies reached the maximum values （above80%）, and the fractal dimension is also reached1.377. Too high ortoo low turbulent kinetic energy and available energy dissipation rate were not favourable forthe formation of integrated and closed vortices. Therefore, the flocculation efficiencies werelower.