基于数据拟合法的三角形薄壁堰明渠流量测量不确定度优化

Optimization of Flow Measurement Uncertainty in Open Channel with Triangular Thin-walled Weir Based on Data Fitting Method

针对三角形薄壁堰明渠流量计非定点使用时测量准确度水平较低的问题,基于不确定度预评估结果,提出了以曲线拟合替代线性插值计算流量系数,采用了数字输出磁致伸缩水位传感器测量水头,显著降低了原方法中贡献较大的不确定度分项。基于弗劳德相似准则改进了频率采样方法,提升了测量结果的准确度水平。测量方法改进后不确定度由1.6%提高到0.56%。通过标准表法明渠流量流速标准装置对三角形薄壁堰明渠流量计进行了标定实验,实验结果表明:测量方法改进后标定误差(偏差)由2%降低到1%。

Aiming at the problem of low measurement accuracy of triangular thin-walled weir open channel flowmeter when used at non-fixed points,based on the uncertainty pre-assessment results,it is proposed to use curve fitting instead of linear interpolation to calculate the flow coefficient,and a digital output magnetostrictive water level sensor is used to measure the water head,which significantly reduces the uncertainty items that contribute more to the original method.Aiming at the problem of low accuracy level of the triangular thin-walled weir open channel meter when it is not used at fixed point,the research on the measurement method was carried out based on the results of the uncertainty pre-assessment.Curve fitting is proposed to replace linear interpolation to calculate the flow coefficients,and a digital output magnetostrictive water level sensor is adopted to measure the water head,which significantly reduces the uncertainty component of the original method.The frequency sampling method is improved based on the Froude's similarity criterion,which improves the accuracy level of the measurement results.The uncertainty of the measurement method is improved from 1.6%to 0.56%.The calibration experiments of the triangular thin-walled weir open-channel flowmeter are carried out by the standard meter method open-channel flow rate standard device,and the experimental results show that the measurement error is reduced from 2%to less than 1%after the improved method.the calibration error(deviation)was reduced from 2%to 1%after the improvement of the measurement method.