Abstract: Multi-path ultrasonic flow measurement devices have mature mathematical models when used for flows in pipes or rectangular culverts. But measurement difficulty is greatly increased, when applied to a converging intake of pumping stations, due to the change in its cross-sectional area and complicated distribution of flow velocity. We conduct CFD simulations of the internal flow field in the converging intakes of the Qian Liulin pump station, analyze the path velocity distribution characteristics of the ultrasonic device, and compare the measurement accuracy of two different flow calculation models. The results show a flow rate calculation error of roughly 3% - 4% that is caused by applying the rectangular algorithm to calculation of the converging intakes. And for a converging intake, accuracy improvement by the rectangular optimization algorithm OWIRS is not applicable, while its measurement accuracy can be improved through modifying the location of the Gauss-Legendre calculation section. Path losing in actual measurement will cause an obvious deviation of the flow measurement, and the curve fitting method can compensate the deviation to a certain extent.

Key words: ultrasonic flow measurement device, converging intakes, CFD, flow deviation, path losing