Experimental and Numerical Research of the Effects of a Perturbed Inflow of a Centrifugal Pump

The influence of a disturbed inflow condition on a single-stage, end suction volute casing pump, as they are frequently found e.g. in water supply plants, was analyzed experimentally in a test bench and numerically using CDF simulation. The analyzed pump operates with water and has a specific speed (n_s) of 42 (metric units), an outside impeller diameter (D₂) of 188 mm and an operating speed (n) of 2300 rpm. The measurements were carried out in a closed test loop where the operating conditions and the inlet piping can be varied to analyze the influence of bend and valve over the pump performance. For the 3-D numerical analysis two configurations were simulated. First the combination bend and butterfly valve was calculated and second the complete pump. Different coupling methods between fixed and rotating parts and some turbulence models were analyzed. For the comparison between experiment and simulation the characteristic curves of the pump are used. Also the calculated flow distribution directly upstream of the suction branch of the pump was compared with the velocity profile measured non-intrusively with a Laser Doppler Velocimeter (LDV). The aim of the study is to determine the effects of a disturbed flow at the inlet of a pump on its performance and to analyze the causes of these effects using CFD.