Influence Of Gap Leakage On The Strength Of Impeller And Cavitation Characteristic Of Centrifugal Pump

The effect of the wear-rings were usually ignored in the numerical simulation of the flow field in a centrifugal pump to cut the calculation time and process and improve design efficiency,therefore,the results were incomplete and inaccurate The centrifugal pump first impeller of type DG-350 was selected as a test model.the internal flow field of the centrifugal pump is numerically simulated under the condition of considering the gap of the wear-ringsBased on ANSYS FLUENT,the N-S equations,the standard k-? turbulent model and the SIMPLE algorithm were adopted in the simulation.The effects of different size of clearance of wear-rings(0.3mm,0.5mm,0.7mm)on the pump properties were studied.Under different working conditions,the distribution of pressure,velocity,turbulent kinetic energy and cavitation area distribution of the key parts such as the impeller,guide vane and wear-rings clearance were obtained.And the cavitation distribution in the impeller channel was also given.Based on fluid-structure interaction,the first impeller of DG-350 multistage centrifugal pump was taken as a test model by ANSYS WORKBENCH.The influence of clearance leakage on the impeller deformation and strength was studied.The deformation distribution and equivalent stress were obtained through sequential fluid-solid coupling and strong fluid-solid coupling respectively.Compared with the engineering requirements,both the error of simulation and experimental results are about 5%which indicates that the calculation and simulation results are accurateThe analysis shows that the clearance between wear-rings has reduced the pressure difference between the inlet and outlet of the impeller.With the increase of wear-rings clearance,the energy consumption,hydraulic loss and volume loss in the centrifugal pump will increase,which decreases the efficiency of centrifugal pump Due to the presence of velocity vortices at the intersection of the wear-ring clearance and the inlet section,the pressure at the intersection of the inlet section on the centrifugal pump and the front wear-ring clearance is lowered,which results in cavitation.With the increase of wear-ring clearance,the cavitation area on the impeller channel also increases.Thus,the flow area of fluid is reduced and the fluid velocity and NPSHr are increased.Analysis and comparison of the coupling results show that the cavitation area at the import section of the impeller is increased.The clearance between the wear-rings results in great pressure between the impeller and the guide vanes which acts on the impeller front and rear covers,offsets some fluid pressure on the impeller cavity and reduces the deformation and stress concentration on the impeller.