The Numerical Simulation Study On Densadeg

DENSADEG introduced from Europe in recent years is a water treatment structure dealing with problems of flocculation,precipitation and concentration.The flow field inside DENSADEG is much more complex than other water treatment structures.The study of DENSADEG in China is still locating in the initial stage.Therefore it is necessary to study DENSADEG under different hydraulic conditions.Herein,based on the numerical simulation,the flow field and flow characteristics in the DENSADEG with different scale are presented,and the results of flocculation caused by different geometry of agitator tank,length-width ratio of mixing flocculation area,water hole position and the diversion plate are studied by observing the index of turbulent kinetic energy k and turbulent kinetic energy dissipation rate ? in order to achieve the optimized design parameters of the DENSADEG.By analyzing the results of the simulation,it is obtained that the flocculation is affected by the different diameters of the agitator tank when keeping other structural parameters as constants.The optimal diameter of agitator tank is dependent on the impeller's diameter.It is shown in detail that the optimal diameter of agitator tank increases with the increment of the impeller's diameter.In addition,the optimal diameter of agitator tank D can be characterized through the ratio of D/d=1.28~1.4,where d indicates the diameter of the impeller.The turbulent kinetic energy k and turbulent kinetic energy dissipation rate ? in DENSADEG with diversion plate are higher than the ones obtained from the simulation of DENSADEG without diversion plate.By changing the location of the water hole,it can be found that turbulent kinetic energy k and turbulent energy dissipation rate ? decrease with the increment of the height of the position.Therefore,the optimum flocculation can be achieved when setting the water hole locating at the bottom.It also can be concluded from the simulation of the mixed flocculation zone with different length-width ratio that the flow turbulence intensity for the length-width ratio 1:1 is more significant than the one of 1:2and 2:3.The dissertation provides reference values and practical guiding significance for the engineering design and operation of DENSADEG in the future.