This work is concerned with the study of the slip phenomenon in centrifugal pumps and the evaluation of its dependence on the flow rate for a four-bladed pump. The finite volume method is used, and the impeller domain is represented by a structured grid topology. The calculations assume a rotationally periodic boundary condition, while the frozen rotor technique is used to model the interaction between the pump impeller and its surrounding volute casing. The simulation uses an implicit time integration of the dynamic equations and is carried out using the commercial ANSYS CFX-solver. Results from the simulation are found in reasonable agreement with the pump performance curve with a maximum relative error of 4% in the range of flow coefficient from 0.8 to 1.2. The calculated values of the slip factor, as a function of the flow rate, show good agreement with the Qiu’s mathematical model while retaining the default value of the defined shape factor F = 0.52. In this particular study, the results show that although the slip factor improves with the increase of either the number of blades or splitter length, the corresponding predicted hydraulic efficiency decreases due to the increasing friction loss.

Slip phenomenon is very important factor by it we can know the actual amount of energy transferred to fluid. In this study i test the different parameters which may affect on this phenomenon such as discharge, exit flow angle, number of blades, type of fluid. i found the old Busemann, Stodola, Stanitz, Wiesner, Eck and SRE is correct in some cases only because these relations don't study all factors affected on slip factor. Also the trend of the slip factor in new study such as in X. Qiu there are case which upward trend and others downward trend thus I focus on this phenomenon in this paper.