Numerical and Experimental Study on the Shutdown Transition Process of a Large Axial Flow Pump System Focusing on the Influence of Gate Control

Abstract

Large axial flow pump systems (LAPS) are widely used in coastal pump stations. In the actual operation of a LAPS, various accidents often occur during shutdown due to the unreasonable control of stop flow measures such as the gate. In this paper, based on the secondary development of Flowmaster numerical software, a numerical simulation study was conducted on the shutdown process of a LAPS with different gate control laws. It was found that the MBV of the shutdown process was greater if the gate was closed more slowly after the unit was powered off. When a 30 s shutdown scheme was used, the MBV during shutdown was 1.63Qr. When a 60s long shutdown scheme was used, the MBV during shutdown was 1.67Qr, an increase of 2.45%. When the 150s long shutdown scheme was used, the MVV during the stopping process reached 1.68Qr, which is an increase of 3.07%. The shutdown method of closing the gate in advance can significantly improve the violent fluctuations of the KCPs of a LAPS during the shutdown transition and will effectively reduce the backflow and the reverse speed of the pump during the shutdown process. Taking the total gate closing time of 120 s as an example, when the 25% gate was closed in advance, the MBV and MRS during the shutdown process were reduced by 14.31% and 1.93%. When the shutdown scenario of preclosing 100% of the gates was adopted, the MBV and MRS during shutdown were reduced by 96.31% and 100%.