数值积分函数对超声波流量计精度的影响

针对数值积分函数在超声波流量计计量过程中会引入固有误差的问题,对常用的4种积分函数在Re为1.0×103～1.0×107区间的固有误差进行了比较.通过建立超声波流量计数学模型,结合发展管内流速的分布规律,计算各积分函数的2～5个声路的误差,得到了误差分布曲线.研究结果表明:各积分函数的声路数越多,引入的固有误差越小,当Re大于等于1.0×105时,各积分函数的引入误差随着Re的增大逐渐趋于稳定.在声路数不受限制且管路流量检测范围内会出现最大引入误差时,Gauss-Legender积分具有明显优势.当Re大于等于8.0×103、小于等于4.0×105时,Tailored积分具有较小误差,而Owics积分更适用于声路数受限制和Re大于4.0×105的管路流量检测.

Influence of Numerical Integration on Error of Ultrasonic Flowmeter

Comparative research was carried out on the inherent error of four commonly used inherent in the Reynolds number interval 1.0×103-1.0×107 according to the inherent error introduced by the numerical integration of ultrasonic flowmeters during the measuring process.From the mathematical model of an ultrasonic flowmeter and the universal velocity distribution of a fully developed pipe flow,the error of integrations of a flowmeter with two to five acoustic paths was calculated,and the error distribution curves were obtained.The results show that inherent error introduced by the integration decreases with an increase in the number of acoustic paths.When the Reynolds number is higher than 1.0×105,all the integrations’ importing error is gradually stable.However,Gauss-Legender has obvious advantages when the number of acoustic paths is unlimited and the maximum importing error occurs in the flow detecting range.Tailored has a smaller error than the others in the Reynolds number range of 8.0×103-4.0×105.Owics is more suitable for the flow measurement where the number of acoustic paths is limited and the Reynolds number is higher than 4.0×105.