Analysis of numerical instability of centrifugal pumps operational characteristics

In recent years, computational fluid dynamics has been increasingly used in the development of various types of rotating machines. In the case of water turbines and pumps, a large number of researches have been published recently, related to the use of different numerical methods for prediction of efficiency, cavitation characteristics and different dynamic phenomena. For basic analysis an accurate result near the optimal operating regime is sufficient, but for detailed analysis the numerical analyses in the wider field of operating conditions are necessary. Thus, we encounter some otherwise known physical phenomena that occur in the part load and full load regime. In these areas, due to the nature of the flow, various non-stationary phenomena occur that are dominant for such operating regimes. In this paper, the problems that arises if we consider only stationary results and some recommendations to avoid later problems in the operation of centrifugal pumps are presented.