The formation of an inlet vortex seriously restricts axial-flow pump device performance and poses a great threat to the safe and stable operation of the entire system. In this study, the change trends of an inlet vortex and its influence on an axial-flow pump are investigated numerically and experimentally in a vertical axial-flow pump device. Four groups of fixed vortex generators (VGs) are installed in front of the impeller to create stable vortices at the impeller inlet. The vortex influence on the performance of pump device is qualitatively and quantitatively analyzed. The vortex patterns at different positions and moments in the pump device are explored to reveal the vortex shape change trend in the impeller and the pressure fluctuation induced by the vortex. The reliability and accuracy of steady and unsteady numerical results are verified by external characteristics and pressure fluctuation experimental results. Results show that it is feasible to install VGs before the impeller inlet to generate stable vortices. The vortex disturbs the inlet flow fields of the impeller, resulting in significant reductions of the axial velocity weighted average angle and the axial velocity uniformity. The vortex increases the inlet passage hydraulic loss and reduces the impeller efficiency, while it only slightly affects the guide vane and outlet passage performance. The vortex causes a low-frequency pressure pulsation and interacts with the impeller. The closer the vortex is to the impeller inlet, the more significant the impeller influence on the vortex. The blade cuts off the vortex in the impeller; afterwards, the vortex follows the blade rotation, and its strength weakens.

In order to study the stability of power generation in reverse of a pumping station unit, the computational fluid dynamics simulation and finite element analysis of the whole passage has been carried out, to study the pressure pulsation and stress distribution law under the condition of power generation in reverse, and compared with them in pump mode. The simulation results showed that, under the condition of power generation in reverse, the pressure pulsation of each monitoring point in front and at back of the runner were higher than that under pump mode. The most amplitude of pressure pulsation was about twice as large as the pump mode, increased gradually from hub to rim. The flow was seriously affected by the rotating runner. The internal frequency of pressure pulsation was blade frequency. The results of fluid–solid coupling showed that the stress mainly concentrated on the root of the pressure side and the suction side of the blade, and the maximum equal stress appeared on the suction side of the blade. The maximum stress and strain value under the condition of power generation in reverse were 20% higher than that under pump mode, and the maximum stress was about twice.

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This paper proposes a novel three-dimensional (3D) isolation system for facilities and presents the numerical simulation approach for the isolated system under earthquake excitations and impact effect using the OpenSees (Open System for Earthquake Engineering Simulation) software frame work. The 3D isolators combine the quasi-zero stiffness (QZS) system in the vertical direction and lead rubber bearing in the horizontal direction. Considering the large aspect ratio of the isolated facility, linear viscous dampers are designed in the vertical direction to diminish the overturning effect. The vertical QZS isolation system is characterized by a cubic force-displacement relation, thus, no elements or materials can model this mechanic behavior in the existing finite element software. This study takes advantage of the open source feature of the OpenSees to create a new material to represent the mechanic properties of the QZS system. Then the user-defined material is combined with the rubber isolator element to model the 3D isolator. Considering different soil types and input magnitudes, six sets of natural seismic records and artificial waves and half sine pulses are selected as the input excitations. A finite element model for the 3D isolated facility is established based on the combined element and the simulation is performed to calculate the time history response. The numerical simulation reveals the flexibility of the OpenSees to deal with new engineering problems, and the results prove that the new 3D isolation system can have an optimal isolation effect in both horizontal and vertical directions. The maximum acceleration response at the top of the facility is below the target limit, and the maximum deformation and the overturning motion of the isolation system can be controlled in a safe range.

In non-design conditions, severe hydraulic instability can affect the stability of a pump station and even shorten its service life. A Francis pump station in the South-to-North Water Transfer Project was examined to carry out a numerical simulation of the entire flow passage using a bidirectional fluid–solid method for static and fatigue life. Due to the inlet setting, reverse power generation exhibited a more distorted flow pattern that resulted in higher energy loss than the pump condition. The radial force acting on the blades in reverse power generation was 39.1% higher. Runner stress was mainly concentrated at the leading edge and blade edge. The maximum stress in reverse power generation was 35.7 MPa, which was about 28.5% higher than in the pump condition. While the maximum deformation was 0.035 mm, almost 94.4% more severe than in the pump condition, mainly concentrated at the leading edge. Based on the fatigue analysis, a minimum safety factor obtained numerically was 8.238 in the pump condition and 6.343 in the reverse power condition, respectively. The safety factors satisfy the safety standard of the runner material and meet requirements of safety and stability in the reverse power generation condition.