Numerical simulation and experimental study of transient characteristics in an axial flow pump during start-up

In order to explore the impact load and instantaneous fluid pressure of transient flow on pump station system under the nonregulative operating conditions, the transient characteristics of an axial flow pump during start-up process are investigated experimentally and numerically. To simulate transient flow of the pump, the rational speed is set by force coupling. In order to simulate the movement of the gate with two flap doors attached, the moving mesh technique is adopted. The results of numerical simulation agree well with the experimental data. During the start-up transient process, the transient characteristics parameters, such as pump rotational speed, head, and flow rate change significantly. Transient impact head rises to a peak of 1.87 times the rated head as the rotational speed reaches the rated speed. The whole impeller passage is full of recirculation, flow separation and vortices. The pressure distribution of the impeller blade changes obviously. In the process of pump start-up, the vortex core zones gradually increase, massively appear at the leading edges of the blade and in the passage of the impeller at t = 0.6 s, and then decrease. Our studies could help to avoid pump vibration and blade crack in engineering. (C) 2019 Elsevier Ltd. All rights reserved.