Numerical investigation of axial force of a centrifugal pump in the reverse mode

Abstract

This paper numerically investigates the hydraulic performance and axial force of a low specific speed centrifugal pump in the turbine mode using the k - ω SST model. Numerical results are validated against the experimental data in the literature and a good agreement is observed. Results show that the rotation factor increases by flowrate, since the head, which is directly proportional to the transferred circumferential momentum, increases by the flowrate in the turbine mode. Moreover, values of rotation factors on both sides varies in radial direction due to geometrical parameters and, they reduce where larger axial gaps are present. Additionally, the pressure distributions on the hub and shroud sides are correlated with rotation factors on these areas. Interestingly, the axial position of the impeller plays an important role in the axial force of the PAT. By applying impeller movement of 5 mm from its original position, the point of zero axial force has shifted to higher flowrates and the maximum axial force is reduced 50%. Finally, with 10 mm movement of the impeller, the axial force exhibits distinct behavior so that its direction is preserved and, the returned magnitude is almost constant in the working range by 60% decrease in the maximum axial force.