Numerical simulation of transient flow in a shaft extension tubular pump unit during runaway process caused by power failure

In this paper, we analyzed the live fish trajectory recorded from an experiment in an experimental vertical slot fishway. Combined with a numerical simulation, we demonstrated that randomness shown in fish trajectory might not merely be attributed to fish's random choices in its swimming, also could be an adaption consequence to the bulk unsteady turbulent flow structure. Simple superposing the fish trajectory on the time-averaged flow field obtained either by interpolating on discrete point measurements or numerical simulation is not an ideal method for fish movement description in fishway engineering. How to model the fish paths in transient flow and the necessity of simultaneous recording of the flow field and the fish locomotion are challenging topics. The suggested spectrum analysis of the flow field may provide a new general method to reproduce the fish trajectory in a complex turbulent flow.

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Mathematical Modelling Forecast on the Idling Transient Characteristic of Reactor Coolant Pump

Processes ◽

10.3390/pr7070452 ◽

2019 ◽

Vol 7 (7) ◽

pp. 452 ◽

Cited By ~ 1

Author(s):

Wang ◽

Xie ◽

Lu ◽

Zhu ◽

Fu ◽

...

Keyword(s):

Transient Flow ◽

Guide Vane ◽

Characteristic Curve ◽

Hydraulic Modeling ◽

Modeling Framework ◽

Coolant Pump ◽

Important Indicator ◽

Reactor Coolant ◽

Power Failure ◽

Accident Condition

The idling behavior of the reactor coolant pump is referred to as an important indicator of the safe operation of the nuclear power system, while the idling transition process under the power failure accident condition is developed as a transient flow process. In this process, the parameters such as the flow rate, speed, and head of the reactor coolant pump are all nonlinear changes. In order to ensure the optimal idling behavior of the reactor coolant pump under the power cutoff accident condition, this manuscript takes the guide vanes of the AP1000 reactor coolant pump as the subject of this study. In this paper, the mathematical model of idling speed and flow characteristic curve of reactor coolant pump under the power failure condition were proposed, while the hydraulic modeling database of different vane structure parameters was modeled based on the orthogonal optimization schemes. Furthermore, based on the mathematical modeling framework of multiple linear regressions, the mathematical relationship of the hydraulic performance of each guide vane in different parameters was predicted. The derived model was verified with the idling test data.

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Role of Transient Characteristics in Fish Trajectory Modeling

Sustainability ◽

10.3390/su12176765 ◽

2020 ◽

Vol 12 (17) ◽

pp. 6765

Author(s):

Gao Zhu ◽

Zuhao Zhou ◽

Helge I Andersson

Keyword(s):

Numerical Simulation ◽

Flow Field ◽

Transient Flow ◽

Silver Carp ◽

Simultaneous Recording ◽

Trajectory Modeling ◽

Fish Locomotion ◽

Vertical Slot ◽

Ideal Method

In this experiment, we analyzed live fish (silver carp) trajectories recorded in an experimental vertical-slot fishway. Combined with a numerical simulation, we demonstrated that randomness shown in fish trajectories might not merely be attributed to the fish’s random choices in its swimming, but could also be a consequence of adaption to the bulk unsteady turbulent flow structures. Simple superposition of a fish trajectory on the time-averaged flow field obtained either by interpolating on discrete point measurements or numerical simulation data is not an ideal method for description of fish movement. How to model the fish paths in transient flow and the necessity of simultaneous recording of the flow field and the fish locomotion are challenging topics. We also discussed the possible integration of currently existing methods to promote the development of fish trajectory modeling.

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