Unsteady flow characteristics in centrifugal pump based on proper orthogonal decomposition method

Considering the complexity flow characteristics and the rotation curvature effect on the internal unsteady flow in a centrifugal pump, a hybrid Reynolds-averaged Navier–Stokes/large eddy simulations method based on the von Kármán scale and the correction of the rotation curvature has been established, and its effectiveness has also been verified. Proper orthogonal decomposition method is used to study the internal unsteady flow structure in a centrifugal pump for its advantages on turbulence analysis. Further, the complex flow characteristics of the vertical single-stage marine centrifugal pumps have been studied, and the relationship between the energy distribution characteristics of the internal flow structure and hydraulic performance has been explored under different operating conditions. The results show that when the fluid flows into the impeller, which is affected by the angle of attack of the inflow, system rotation, and bending blades, the flow separation occurs and leads to an unstable flow in the impeller. The obvious pressure fluctuations emerge on the blades surface, which affects the energy conversion ability of blades. The poor inflow in the impeller causes the low local pressure could also affect the anti-cavitation ability of the centrifugal pump. In addition, there are multi-scales of the flow structures in the centrifugal pumps, and the energy distribution of flow in the centrifugal pump with good hydraulic performance is more concentrated in low-order and large-scale flows structures, and the high-order and small-scale flow structure contains less energy, which indicates that the energy distribution characteristics of the flow structures could be used as a criterion to evaluate the performance of the centrifugal pump.