Numerical simulation of the stalled flow within a vaned centrifugal pump

Abstract

The main goal of the present work is to analyse the numerical simulation of a centrifugal pump by solving Navier-Stokes equations, coupled with the ‘standard k-∊’ turbulence model. The pump consists of an impeller having five curved blades with nine diffuser vanes. The shaft rotates at 890r/min. Flow characteristics are assumed to be stalled in the appropriate region of flowrate levels of 1.31-2.861/s. Numerical analysis techniques are performed on a commercial FLUENT package program assuming steady, incompressible flow conditions with decreasing flowrate. Under stall conditions the flow in the diffuser passage alternates between outward jetting when the low-pass-filtered pressure is high to a reverse flow when the filtered pressure is low. Being below design conditions, there is a consistent high-speed leakage flow in the gap between the impeller and the diffuser from the exit side of the diffuser to the beginning of the volute. Separation of this leakage flow from the diffuser vane causes the onset of stall. As the flowrate decreases both the magnitude of the leakage within the vaneless part of the pump and reverse flow within a stalled diffuser passage increase. As this occurs, the stall-cell size extends from one to two diffuser passages. Comparisons are made with experimental data and show good agreement.

PIV measurement on internal instantaneous flows of a centrifugal pump

“…All impellers showed the rotating cavitation of a very similar mechanism over a wide range of part load flow rates. Guleren and Pinarbasi (2004) [8] pointed out that the stall-cell size extended from one to two diffuser passages.…”

Performance prediction and flow analysis in the vaned distributor of a pump turbine under low flow rate in pump mode

“…Recently, with the rapid development of computational fluid dynamics (CFD), numerical study for stalled flow is becoming popular. Guleren [5] carried out the simulation to study the stalled flow in a vaned centrifugal pump by using a commercial software, and it was observed that the vane diffuser exerts a significant effect on the pump performance. Tsukamoto [6] proposed an intergration method which coupled the 3D modeling of pump with 1D pipe system to investigate the performance prediction of a diffuser pump under off-design conditions.…”

Unsteady flow visualization at part-load conditions of a radial diffuser pump: by PIV and CFD

“…Rotating stall in the diffuser region of a radial pump has been observed at low flow rate by some authors, such as Sinha et al (2001) and Sano et al (2001) by PIV measurements, and Guleren and Pinarbasi (2004) by numerical simulation with a commercial CFD code FLUENT. Pedersen et al (2003) found a steady stall at quarter flow rate in a vaneless impeller by PIV.…”