Cavitation Induced Accelerated Erosion In Large Slurry Pumps

Centrifugal slurry plumps experience accelerated erosion. Research to understand and to control has been inconclusive. This investigation is being conducted to qualitatively examine the patterns of accelerated erosion in the samples photographed or collected from slurry pumps in the field, and to compare with the patterns on an aluminium specimen eroded by a submerged fast moving cavitating water jet in abrasives. The selected field samples are a front liner, and the front shroud of an impeller. The examination has resulted in: (1) Identification of three areas in slurry pumps which experience accelerated erosion the front liner, the front shroud and the impellerâs vanes. (2) Identification of the three common features both in the samples and in the aluminium specimen; namely: directional groves along the direction of the main slurry-flow, cavities and pitting, and the embedding of abrasive in the surfaces. The paper concludes the common features of localised cavitation and corresponding accelerated erosion in slurry pumps which are observed in the lowest local pressure areas. The current definition of cavitation is based on the lowest mean-pressure in the cross section area is replaced with a lowest-localpressure based definition which is followed with redefinition of the Cavitation Number based on local parameters, the flow mapping of vortexes, vortices, flow separation behind obstacles, and tensile forces within a velocity boundary layer, and prediction of localised cavitation at the design stage, and adopting cavitation erosion preventative measures such as air entrainment in erosion areas