Numerical Procedure for Assessment of Centrifugal Pump Cavitation Erosion

Abstract

Currently the cavitation erosion damage becomes a critical issue that limits the centrifugal pump life cycle extension. Despite of a long history of studying the cavitation erosion phenomenon in centrifugal pumps there are still no reliable assessment methods except semi-empirical formula having rather limited application and accuracy. The paper is presenting a novel method for assessment of centrifugal pump cavitation erosion combining 3D unsteady flow CFD modeling and numerical analysis of cavitation bubbles behavior. The Navier-Stokes equations are solved by a splitting method with the implicit algorithm and high-order numerical scheme for convective transfer terms. The 3D numerical procedure is based on non-staggered Cartesian grid with adaptive local refinement and a sub-grid geometry resolution method for description of curvilinear complex boundaries like blade surfaces. Rotation is accounted with implementation of “sliding-grid” technology. The method considers evolution of the bubble in 3D flow from initial conditions until the disruption moment with determination of the erosion jet power impact. Validation of the method on model feed centrifugal pump stages is completed for two model centrifugal impellers Centrifugal impeller #1 is designed with a goal of through-passed shaft pump flow modeling. There are completed computations of cavitating bubbles’ evolution under non-uniform pressure field that show the non-uniform pressure distribution near the blade surface causes an essential influence on cavitation erosion. Computational prediction of the impeller #1 cavitation erosion damage is confirmed experimentally.

Prediction of cavitation and induced erosion inside a high-pressure fuel pump

“…Hence, a piecewise EoS was used based on the following component functions: 33,35 The Tait EoS was used for the liquid phase where the factor B corresponds to the bulk modulus of the liquid and n is an exponent determining the stiffness of the Tait EoS, commonly set to 7.15 for weakly compressible liquids. 22 The density predicted by the Tait EoS was tested and found to be in good agreement with the literature data for diesel fuel, 32 for the temperature level and the pressure range in the pump. In fact, the maximum error is less than 0.7% for pressures up to 2000 3 10 5 Pa, which is considered negligible.…”

“…Studies focusing on the factors affecting the development of cavitation erosion especially in reference to pumping devices are scarce in the literature and mainly focus on radial-flow configurations. Timushev et al 22 evaluated two centrifugal pump designs in terms of sensitivity to cavitation-induced erosion. It was deduced by the authors that the probability of surface-erosion occurrence was dependent on the pressure gradient normal to the impeller wall.…”

Πειραματική Και Υπολογιστική Διερεύνηση Ροϊκής Συμπεριφοράς Φυγοκεντρικών Αντλιών

“…Αρκετές εργασίες έχουν επικεντρωθεί στη µελέτη της επίδρασης της γεωµετρίας του χείλους προσβολής στη σπηλαίωση [62][63][64] , αλλά και στη µελέτη της επίδρασης της σπηλαίωσης στην απόδοση της φυγοκεντρικής αντλίας [65][66][67] . Επιπλέον, υπάρχουν αναφορές για την επιρροή του σχεδιασµού της φυγοκεντρικής αντλίας στην ανάπτυξη της σπηλαίωσης, µελετώντας το φαινόµενο ως µη µόνιµο [68] .…”