基于关节臂的超声测流装置几何参数精测方法研究

针对如何确保现场安装超声测流装置测量准确度的问题,提出了基于关节臂的现场安装探头几何参数精测方法。 首先,对超声测流装置的流量计算模型进行分析,结果表明,其测量准确度建立在探头几何参数的准确测量基础上。 在此基础上,通过探头的特殊设计及内外测比对试验,验证了使用关节臂外测探头三维坐标推算探头实际几何参数的可行性。 最后,在南水北调中线工程的 3 个试点,使用关节臂精确测量插入式四声道超声测流装置探头三维坐标,分析得到探头几何参数的精确量值和修正权重系数。 通过分析不同权重系数对超声测流装置平均流速的影响,结果表明,该方法能提高现场安装的超声测流装置测量准确度 0. 02% ~ 0. 58%,对现场划线定位的准确度水平做出评价,验证了方法的合理性和有效性。

Research on precise measurement method of geometric parameter of ultrasonic flow measurement device based on AACMM

Aiming at the problem of how to ensure the measurement accuracy of the on-site mounted ultrasonic flow measurement device,a precise measurement method of geometric parameters of the on-site mounted probe based on articulated arm coordinate measuringmachine(AACMM) is proposed. Firstly, the flow-rate calculation model of ultrasonic flow measurement device is analyzed, the resultsshow that the measurement accuracy is based on the accurate measurement of the geometric parameters of the probes. On this basis,through special design of probe and comparison of internal and external test, feasibility of using external probe 3-D coordinates valuemeasured by AACMM to calculate probe actual geometric parameters is verified. Finally, in three test cases of middle route of south-to-north water transfer project, 3-D coordinates value of probe of plug-in four-path ultrasonic flow measurement device are accuratelymeasured by AACMM, precise geometric parameters of the probe and corrected weight coefficients are obtained by analysis. Throughanalysis of the influence of different weight coefficients on the average flow velocity of ultrasonic flow measurement device, the resultsshow that the method can improve the measurement accuracy of the on-site mounted ultrasonic flow measurement device by 0. 02% ~0. 58%, the accuracy of scribe localization is evaluated, and also the rationality and effectiveness of the method are verified.