Numerical investigation on flow distortion in a vertical inline pump

Abstract

The vertical inline pump is a centrifugal pump with special structures of curved inlet pipe before the impeller, and it is widely used in where the constraint is installation space. However, the elbow inlet with different angles and cross sections also deteriorates the impeller inflow and results in flow distortion in the impeller. For the purpose of further investigation of flow distortion in the vertical inline pump, the unsteady Reynolds averaged Navier-Stokes equations were solved by the commercial CFD code with the shear stress turbulence model. The normalized coefficients of inlet velocity, pressure, helicity, and non-uniformity were applied to quantitatively analyze the flow distortion in the pump. The computational results showed a great agreement with the experimental results. Under the nominal and overload conditions, the flow separation and counter-vortex pair were found on the outer side of the inlet pipe and the intensity of these phenomenon increases along with the rise of flow rate. However, the flow recirculation was observed under the part-load condition which becomes the major reason for the flow distortion in the inline pump.