This work uses a commercial computational fluid dynamics code to predict threedimensional (3D) vortex flows in a large centrifugal-pump station under construction in China and proposes relevant vortex-eliminating schemes. Because of the complex nature of the vortex flows in sumps, different turbulence models, namely, standard k-ε, re-normalization group k-ε and realizable k-ε models, are first used to investigate their feasibility in predicting flows in a small physical model of an open pump sump, and various vortex streamlines and strength in the sump are predicted, analysed, and compared with the experimental data. The comparisons show that the realizable k-ε model predicts the position and strength of free-surface, sidewall-attached, and floor-attached vortices more accurately than the other two models. Then, the realizable k-ε model is used here to investigate 3D vortex flows in a large pumping-station sump. All the various vortices, such as free-surface, wall-attached vortices, are successfully predicted. Thus, based on the information of location, shape, size, and strength of the calculated vortices, three types of vortex-eliminating devices are proposed and their corresponding vortex suppression effects are analysed. These results will be used as reference for the safe and stable operation of the Hui-Nan-Zhuang pumping station in the future.

Vortex in pump station sumps could lead to equipment operation with vibration and cavitations, and its impact is even stronger in large scale pump station sumps. In this study, the flow structure and vortex behavior in the sumps of a large scale pump station were investigated with a three dimensional CFD approach. The approach solves Reynolds averaged Navier-Stokes equations by the realizable k-ε turbulence model with wall function. The numerical simulations were carried out under three different water levels (low, standard and high) and three different pump operating combinations (operating with one, two or three pumps). The important flow feathers in the entire flow field such as submerged vortices, free-surface vortices were revealed. The strength and location of vortices under different operating conditions were presented. To reduce the vorticity magnitude in the sumps which would expand to affect the flow around pump inlet, effects of three different anti-vortex devices (DA, DB, and DC) for the pump station were also investigated numerically. It is found that the vortex attached to the floor has larger vorticity scale than that attached to side wall and back wall. The vorticity magnitude at higher sump water level is smaller than that at lower water level. The operation of multi pumps also has a strong impact to the flow patterns in sumps. Anti-vortex device DB has better performance than the two others, it decreases the floor attached and sidewall attached vortex and makes the pump inlet flow smooth.

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