Abstract: Using unstructured hybrid grid technique and SIMPLEC algorithm, selecting clear water as the medium, a general three-dimensional simulation based on Reynolds Navier-Stokes in multiple reference frames and the RNG turbulence model, is presented for the 80LN-6 screw centrifugal pump with impeller back pump-out vanes. Six different schemes are designed by a change of the number and width of impeller back pump-out vanes of the screw centrifugal pump, the inner flow field in every scheme is simulated, accordingly, the variation of axial thrust in the screw centrifugal pump is obtained. The reliability of the numerical simulation method is indirectly validated by the comparison between global performance characteristics of experimental data and test data. And the simulated data of the six different schemes are analyzed, the results obtained show that after adding the impeller back pump-out vanes, the magnitude of the axial thrust in the screw centrifugal pump changed, and the direction of the axial thrust also changed at different conditions in different schemes. For balancing the axial thrust, there exist optimum values for the width and the number of impeller back pump-out vanes, which have great influence on the distribution of the pressure in seal chamber and volute casing.

Key words: Axial thrust, Global performance characteristics, Numerical simulati, Pump-out vanes, Screw centrifugal pump