Identification and monitoring of wall-attached vortices in open pump intake based on continuous wavelet transform

Abstract Wall-attached vortices in pump intake commonly appear and has a negative impact on the safety and efficiency of the pumping stations. The monitoring of these vortices are crucial for safe operation of the pump intake. In this paper, SAS model were performed on a pump intake with an axial-flow pump installed in the suction pipe. Two submergences (500mm and 600mm, namely 3.33 D L and 4 D L ) and three flow rates (0.8 Q d , 1.0 Q d , 1.2 Q d ) were studied. The continuous wavelet transform (CWT) was applied to the pressure signals near the vortices, showed the similarity of time-frequency characteristics at different points under the same flow rate and water level condition.. It was found that the generation and development were slower for larger submergence. At low flow rate 0.8Qd, the flow angle shows larger deviation from 90°, which causes the higher CWT power. By analyzing the powers of dominant frequencies at all the monitor points, it is recommended to set the monitor points within a rectangle that is 0.77DL and 0.97 DL from the back wall and side wall respectively. The conclusions are suitable for similar intakes under similar conditions with 1.2 Q d of the pump. Also, they can be good guidance for more generalized open pump intakes.