Progressive Erosion and Pump Performance Prediction of Double Suction Centrifugal Pump Vane Based on Dynamic Boundary
The change of overflow boundary morphology with erosion time is important to objectively and realistically reflect the erosion characteristics of double suction centrifugal pumps and erosion morphology.The Euler-Lagrange method and the dynamic boundary method of geometric reconstruction of the erosion wall were used to calculate the solid-liquid two-phase flow of the double suction centrifugal pump of Jingtaichuan Pumping Station in Gansu Province under the average sand content and the value of grain size of the Yellow River.The progressive erosion characteristics of the pump vanes were predicted,and the effects of the vane erosion mechanism and the change of wall geometry on the pump performance were analyzed combining the experimental data.The results showed that taking the maximum value of the impact angle function corresponded to the impact angle α0 as a threshold to distinguish erosion patterns.If impact angle was less than the threshold,the erosion pattern was liking a rounded crater,if it was bigger than the threshold,the erosion pattern was liking a groove.The erosion rate was high in areas where the impact angle was in the range 50°～75°and the impact velocity was high,which both led to high level of blade erosion.The prediction period was divided into three phases based on the characteristics of the rate of change of the hydraulic performance loss.The erosion rate had the largest growth rate in the early stages,but the values were orders of magnitude smaller than those in the middle and late stages,so that the head loss rate,efficiency loss rate and mass loss rate of blade in the first 1 000 hours of erosion was less than in other stages.All these parameters showed a trend of slow growth in the early stage,fast growth in the middle stage and slow growth in later stage,and maximum growth rate in the middle stage,values of 1.51×10-3,1.97×10-3,and 4.12×10-3 respectively.Erosion caused the fastest performance degradation of double suction centrifugal pump in the 1 000 hours to 6 000 hours erosion length range.
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