Design Of Impeller Of Submersible Mixer Based On Characteristics Of Stirring Flow Field

With the deterioration of water resources and environment,our country has attached great importance to sewage treatment.The submersible mixer is a new and efficient diving dasher and push-flow mechanism.The effect of mixing and pushing flow will directly affect the quality of sewage treatment.It can comprehensively improve the design level of the submersible mixer in China and develop the work of sewage water treatment to explore the design theory and analysis of internal flow characteristics of submersible mixer impeller.The hydraulic model of high efficiency submersible mixer can be summarized by studying the internal flow mechanism and flow rule of the mixing flow field.Based on the theoretical analysis,numerical simulation and physical experiment,the submersible stirrer has been systematically studied in this paper,the main research contents and results are as follows.1.Establishing the three-dimension model of axial flow pump impeller and Beit impeller,pool,simplified electric shell model and water guide cone and meshing them by the use of Turbogrid,Pro-E and ICEM.Based on the standard k-ε turbulence model,numerical simulation of axial flow pump impeller and Beite impeller is carried out.2.Through the analysis and comparison of the numerical simulation results of axial flow pump impeller model and Beite impeller model,it is found that(a)the flow fields in the two impeller model pools are generally similar,both presenting the characteristics of axial thrust and radial diffusion.The impeller of submersible mixer can be designed according to the design method of axial flow pump impeller;(b)There is a certain difference in the internal flow field of the two impeller models.The inlet velocity of the axial flow pump impeller is smaller than that of Beit impeller.And the difference in outlet velocity of the former is larger than the latter’s.It is necessary to modify the hydraulic model of axial flow pump impeller to meet the requirement of the impeller model of submersible mixer;(c)By comparing the motor power and flow field characteristics of Beite submersible mixer with and without a duct,it is found that the overall effect of the submersible mixer impeller with a duct is better.3.This paper briefly introduces various design methods of submersible mixer impeller and analyzes the hydrodynamics of submersible mixer.Based on the design method of axial flow pump impeller,the impeller flow channel model is modified.Variable circulation method is adopted to design the impeller.The submersible mixer impeller is designed in three dimensions and meshed by hydraulic design software.4.According to the numerical simulation analysis of the fluid flow field of submersible mixer impeller,it is found that the fluid circulation channel is smooth and the main circulation effect is good,and the liquid flow velocity in the circulation zone is improved effectively.And compared with the other two impeller models,its energy consumption is larger but the mixing area is wider,making the mixing effect superior to the other two kinds of impeller models and comprehensive mixing effect better than the traditional axial flow pump impeller.5.The precise control and measurement of motor speed is realized by the combination of Holzer sensor and frequency converter.The accuracy of the experimental thrust and torque measuring device is high.The error of torque and thrust between numerical simulation values and laboratory is small.Meanwhile,the trend of flow velocity measured by the propeller meter is consistent with the numerical values,which validates the accuracy of numerical simulation and the credibility of the experimental results.