Calculation of unsteady flow in a centrifugal pump With vaned diffuser using staggered and collocated grid methods

For the design of turbomachines like compressors, turbines, fans,and centrifugal pumps, more and more use is made of commerciallyavailable flow simulation software. To the authors bestknowledge, in all cases discretization schemes based on a collocatedgrid are used. However, using a collocated grid method,the incompressible Navier-Stokes equations can suffer from oddevendecoupling. The adaptations necessary to suppress oddevendecoupling in incompressible flows result in calculationswhich are either less accurate or more time-consuming, especiallyfor unsteady flows.In this paper we apply an alternative method based on astaggered-grid approach. The method is ideally suited for calculatingunsteady incompressible flow on highly non-uniformblock-structured grids. The unsteady flow in a radial pump with avaned diffuser is calculated in 2D and compared with results obtainedwith a commercially available code. The time-dependentvelocity and pressure fields are validated with experimental resultsavailable in literature.