超声测流在渐缩流道中的应用及其准确度分析

Application of ultrasonic measurement of water flows in converging intakes and accuracy analysis

多声道超声测流装置用于圆形管道或矩形方涵时具有成熟的数学模型,用于泵站入口的渐缩流道时,由于流道截面积的变化和内部流速分布的复杂性,大大提升了流量测量的难度。本文利用CFD模拟了前柳林泵站渐缩流道的内部流场,分析了超声测流装置的声道流速分布特征,比较了渐缩流道中两种不同流量计算模型的测量准确度。结果表明,渐缩流道中应用矩形流道算法导致的流量计算误差大约在3%~4%之间,矩形优化算法OWIRS的准确度提升并不适用于渐缩流道,通过修正G-L方法计算截面的位置可以提升测量准确度。实际测量中声道缺失会导致明显的流量系统偏差,利用曲线拟合的方法可以在一定程度上使偏差得到补偿。

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.