This paper - part2 presents the results of 3D CFD simulations in a centrifugal pump corresponding to the experimental tests presented in Part 1 . Numerical investigations have been carried out to study the behavior of the same centrifugal pump in the range of flow rates corresponding to the saddle-type instability. The numerical results obtained from numerical simulations performed with ANSYS CFX and based on a steady state approach are compared to the experimental data.
This study aims to reproduce by numerical simulations the head drop induced by the saddle-type instability starting from industrial approaches using two-equation turbulence modeling. Moreover the analysis of the local flow provides explanations about the physical phenomenon behind this instability.
By comparing an approach taking into account the full geometry of the pump and another limited to one blade passage the limits of usual approaches in rotating machinery simulations for the representation of such instabilities are discussed.