Numerical Simulation And Research Of Inverted Umbrella Aeration Machine

Oxidation ditch technology has been widely used and developed in sewage treatment after decades of development,because of its high stability,simple process,low management cost and good effluent quality.As an important equipment in the oxidation ditch process,performance of the aeration device directly affects the efficiency of the sewage treatment system,and the aeration device used in this research project is a vertical parachute type surface aeration machine.At present,most of the parachute impeller is based on empirical or semiempirical formula to derive its hydraulics parameter design,and because of the large size of the parachute aeration machine equipment,the realization of the site requirements are high,equipment structure optimization There are many problems.Therefore,it is very important to use CFX simulation software to simulate the performance of inverted parachute impeller.In this paper,four different structures of inverted umbrella impeller,with the same submerged depth of 0.070 m and rotational speed 140r/min,through the ANSYS CFX simulation software standard k-? model to Landy-7,Hubert,The hydrodynamic characteristics of gas and liquid two-phase flow field in the aeration pool of four different structural table Landy-F and Oxyrator were simulated,and the small test flow field of two kinds of structure Landy-7 and Hubert was verified by particle image speedometer(PIV).The results of CFD simulation and the change of velocity distribution in small test are compared and analyzed,and the accuracy of numerical simulation is verified.The results show that under the same working conditions,four different structures of inverted parachute impeller form a negative pressure zone in the area near the impeller dorsal blade,and the lifting performance of the convection field of different structure impeller is different,among which a large negative pressure zone is formed on the back of the Oxyrator impeller,which can involve more air in the flow field and has good aeration performance.The Landy-7 impeller,which weakens the transverse spokes,shows good performance to the surface flow field of the aeration tank.In terms of the negative pressure formed,the negative pressure produced by the Landy-7 impeller is smaller,and the negative pressure formed by the other three kinds of structure impellers is larger and the difference is small.This paper studies the hydrodynamic characteristics of the flow field of four different structure inverted impeller driven aeration tank are studied,and the influence of the convection field when the impeller structure changes is analyzed,which provides a theoretical basis for the structure design and optimization of the inverted umbrella impeller and the development of the oxidation ditch process.