Study on transient characteristics of pipeline under centrifugal pump shaft stuck condition

Abstract

In the pump system, the water hammer effect generated by the shaft stuck accident will cause great harm to the pump and piping system. In order to reveal the transient characteristics of the pipeline during the transition process of vane-pump shaft stuck, three shaft stuck time of Δt = 0.5 s, Δt = 1 s and Δt = 1.5 s is tested by building a closed test bench of centrifugal pump. And establish a 1:1 closed system three-dimensional model to study the external characteristics and internal flow field changes of the pump and piping system during the transition process of the shaft stuck. The study shows that: The rotational speed curves are non-linearly decreasing; the patterns of change in flow rate show a roughly exponential function trending downward; the heads during the shaft stuck will fall rapidly and reach the reverse extreme value. For the pump inlet piping system, the pressure of each place in the speed down to 0 rpm before the peak, the pressure of the outlet pipeline is always down to the reference pressure. Under the same shaft stuck condition, the pressure change in each place of the inlet piping system is basically the same, and the pressure reaches the peak at the same time. The maximum pressure of the inlet and outlet piping is at the rear 3/4 of the elbow. The closer to the face of the inlet and outlet of the elbow, the greater the load force applied; with the elbow as the demarcation, the pressure gradually increases along the flow direction. By revealing the transient mechanism of system piping during centrifugal pump shaft stuck transient process, it provides a reference basis for the design and accident safety assessment of vane-type pumping system.