CFD optimization of ATT flowmeters installed in short converging intakes of a pump station

The acoustic transit-time (ATT) method is a practical technique for online flow rate measurement. It is suitable for straight pipes, open channels, and even short converging intakes of pump stations. Some effective integration algorithms have been proposed and adopted for flow calculation in pipes and open channels, but further improvements are required for flow in short converging intakes due to their complex geometry. The Qianliulin pump station is the third stage of the cascade pump stations of Miyun Reservoir Regulation and Storage Project for the South to North Water Transfer Project of China. ATT flowmeters were installed in the short converging intakes of the pump station to measure the flow rates; each has the configuration of the double-plane with 4 paths each (i.e., the 8-path configuration). The tool of computational fluid dynamics (CFD) is used to investigate the accuracy of the ATT flowmeters installed in short converging intakes of the pump station. This paper mainly presents the numerical study on the complex flow field of the measuring section. Considering that the flow in the measuring section is sensitive to the fore bay structure, the approach channel and the elbow-shaped culverts are also included in the computational domain. The effects of the flow field on the metering performance under different operating conditions are analysed, and the systematic deviations are evaluated. Further discussion is also made for quantifying the effects of the integration algorithm and the path angle on the calculation of standard flow rates. This study can help optimize the flow rate integration algorithm.