Modification Of Solid Particle Erosion Model And Its Application In The Sediment Erosion Of A Centrifugal Pump

The Yellow River is one of the most representative rivers with high sediment content in the world.The heavy load of sediment has caused severe erosion of pumps used for irrigation along the Yellow River.Researches on erosion of pumps are commonly performed numerically due to the complex flow pattern and erosion mechanism in pumps.The solid particle erosion model is significant in simulating erosion accurately.In this research,six commonly used erosion models were analyzed and a modified erosion model was present based on the Oka model.Erosion mechanism of the double suction centrifugal pump impeller was investigated using the modified erosion model.Erosion of a 90 degree elbow was numerically simulated using six erosion models.Test results showed that the erosion magnitude of the Oka erosion model fit best with experiment.The trend of erosion distribution of the Mclaury erosion model fit best with experiment.According to the experiment data and simulation results of the six models,a modified erosion model was put up based on the Oka model.The constant,the velocity exponent and the impact angle function were modified.A velocity exponent of 1.6 and an addition of abrasive erosion helped in simulating erosion more accurately.Erosion characteristics of the double suction centrifugal pump impeller were studied experimentally using multiple layers of paint method.Experimental data indicated that the leading edge of the blade,suction side of the blade inlet,suction side of the blade outlet and pressure side of the blade outlet were prone to erosion.Both the erosion intensity and erosion area became larger with operation time.Erosion got enhanced with higher sediment concentration in the test.Moreover,relationships of the eroded area of blade suction outlet and pressure outlet with operation time were firstly established and the hyperbolic tangent function fit best with the data.Numerical simulation was performed using the modified erosion model.Numerical results showed that the Rosin-Rammler particle distribution simulated better than the single particle distribution.The key factors influencing erosion rate were different in different locations of the blade.Erosion was severest as accretion rate,impact velocity and angle were large in the leading edge of the blade.Impact velocity was large in the suction side of the blade inlet.Accretion rate and impact angle were large in the region near the cover plate of the blade suction outlet.Particle accretion,impact velocity and angle played similar role in the erosion of blade pressure outlet.The flow pattern in the impeller showed that the recirculation near the cover plate in the blade suction outlet caused the high accretion and impact angle.The increasing fluid flow in the blade pressure outlet caused higher particle velocity thus severer erosion.