Study On The Numerical Simulation And Experiment Of The Flow Field In A Stirred Tank With Double Helical Ribbom And Six Blade Impeller

Stirred equipments are widely used in biopharmaceutical,chemical equipment petroleum refining and other areas.It involves the application of multiple production links to the mixing behavior to complete the corresponding production operation.When the mixing fluid is in a turbulent state in the field of production,how to design a mixing paddle to achieve a shorter mixing time and less power,has been becoming the urgent problem in the non-Newtonian turbulent fluid study.In this paper,the studies of the theory anslysis ? numerical simulation and experimental verification are applied to analyze the mixing time?power consumption and the distribution of the flow field in the mixing process of the impeller combination of the double helical ribbon and six pitched blade turbine impeller,and determining the optimal combination form of the combined impeller and the optimal stirring speed in the stirring process.(1)Based on the Fluent Computational Fluid Dynamics Analysis software,using a multiple reference system(MRF)method and k-? model,for double helical ribbom and six-oblique turbine combined impellers in a tank with a diameter of D=280 mm and the fluid medium of the non-Newtonian(a mixture of glycerin and water)is simulated inside the tank.The effects of the combination of the upper double helical ribbom impeller,the lower turbine impellers and the exchanged position on the flow field characteristics of the mixed medium of glycerol and water in the stirred tank were analyzed.The results showed that the upper double helical ribbom impeller and the lower turbine combined impeller form facilitates the fusion and improves stirring efficiency.(2)Based on the determined combination of impellers,the effects of three different stirring speeds on the flow characteristics are analyzed,and the flow field is compared from the macroscopic flow characteristics,the time-averaged velocity distribution,the power consumption,and the mixing time.The results show that the low-speed mixing effect is not uniform,taking into account the power consumption and other issues,high-speed stirring is not suitable for industrial production,stirring speed needs to be maintained in a relatively stable range.(3)Using the PIV data acquisition equipment to qualitatively describe the macro fluid field of three different kinds speed in the organic glass stirred tank,and numerical simulation results of flow field distribution is basically consistent.That is to say in a certain extent the numerical simulation method can simulate the actual mixing flow,flow field distribution of the low stirring speed cannot occur vortex,and stirring speed is high,the distribution of the flow field tends to be more stable.