Investigation on the Time-Variant Flow in a Single-Blade Centrifugal Pump

Effects of the time-variant flow in a single-blade pump are investigated by numerical and experimental methods. For a numerical approach the three-dimensional, viscous, unsteady flow field in the pump has been achieved by solving the unsteady Navier-Stokes equations (URANS) with a commercial solver. From the obtained periodic flow field the time-variant forces acting at the wetted impeller surface were determined for a complete impeller revolution. To validate the results of the numerical simulations a test stand has been used. The velocity field inside the pump has been measured by using the PIV method. A good comparison to the numerical simulations has been achieved. In a second step the forces acting at the bearings of the pump rotor have been measured. To identify the transient radial forces, the pump has been fitted with special manufactured seats for the roller bearings, which have been equipped with strain gages. The experimental results match the numerical results for the hydrodynamic forces very good. In particular, the good qualitative agreement suggests that predicting the transient flow in (single-blade) centrifugal pumps utilizing a Navier-Stokes solver, is a reliable method to calculate the time-variant hydrodynamic forces. Key-Words: Time-variant flow, centrifugal pump, single-blade impeller