Abstract:In order to study influences of clocking effect of impeller-stator on the performance of multistage axial-flow pump, 3D, unsteady flows in a multistage axial-flow pump are simulated numerically by using CFD method. In the simulations, five positions or clocking positions of a blade leading edge in the second stage impeller relative to the blade leading edge in the first stage impeller are investigated. In the reference case, the angle between two blade leading edges is 0°, and then in the following four cases, this angle is increased by a 9° increment. The pressure fluctuation and pressure loading on blade surfaces are analyzed. It is shown that the maximum variation in the pump head is 4.6% at the clocking position of 36°, but the efficiency is just with a change of 1.2% compared with the reference case. At the first stage impeller outlet, the pressure pulsation amplitude and phase have a small fluctua-tion. The maximum reduction of the pressure pulsation amplitude at the first stage impeller outlet is 16.31%, while the pulsation amplitude, whose average value in time domain and phase at the second stage impeller outlet are affected in a certain degree, causing a 48.27% increasing in the pressure pulsation amplitude and a 1.34% rise in its average value. The pressure loading distribution profiles on the second impeller blade surfaces remain nearly identical at different clocking positions. However, the loading distribution in the case, where the angle between two blade leading edges is 9°, is obviously higher than the other clocking positions.
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