Improving accuracy of pipe flow rate measurement with ultrasonic time-domain correlation method under small number density of reflectors
Improving accuracy of pipe flow rate measurement with ultrasonic time-domain correlation method under small number density of reflectors
复制标题
小反射体数密度下超声时域相关法提高管道流量测量精度
DOI：
10.1016/j.measurement.2021.109439
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发表时间：
2021
期刊：
影响因子：
5.6
通讯作者：
Furuichi Noriyuki
中科院分区：
文献类型：
--
作者：
Wada Sanehiro;Furuichi Noriyuki
讨论了减小反射体数密度对超声时域相关(UTDC)测量误检率的影响。当反射器的数密度降低时，错误检测有望被抑制。这是因为当每个脉冲可以被单独识别时，而不是当一些脉冲重叠时，互相关系数的旁瓣峰值变得更小。然而，随着反射体的数量密度减少，这种分离的波形图案预计会更频繁地出现。由于参考窗口中存在个别脉冲的一部分，所以形成该图案。在这项研究中，通过使用假设的脉冲波形模拟UTDC信号过程，研究了在存在噪声的情况下，脉冲与参考窗口之间的位置关系的影响。仿真结果表明，当脉冲长度小于超声周期的1.7倍时，误检率增加的概率较大。仿真结果还表明，衰减波形区具有较高的误检率。在日本一家国家标准的水流测量校准设施中，对三种不同的反射器数密度进行了流量测量。对产生误检的条件及其对流量误差的影响进行了评估。测量结果与仿真结果吻合较好。此外，本文还提出了一种新的信号处理方法在UTDC测量中的应用，以降低脉冲模式引起的误检率。实验结果表明，该方法有效地减小了流量误差。
This paper discusses the influence of decreasing the number density of reflectors on the false detection rate of ultrasound time-domain correlation (UTDC) measurements. False detections are expected to be inhibited when the number density of reflectors decreases. This is because the sidelobe peaks of the cross-correlation coefficient becomes smaller when each pulse can be recognized separately, rather than when some pulses overlap. However, this separated waveform pattern is expected to occur more frequently as the number density of reflectors decreases. This pattern develops because parts of individual pulses exist in the reference window. In this study, the influence of the positional relationship between the pulse and the reference window in the presence of noise was investigated by simulating the UTDC signal process using an assumed pulse waveform. The simulation results show that there is a high probability of an increase in the false detection rate when the pulse length is under approximately 1.7 times the ultrasound period. The simulation results also showed that damped waveform region has a high potential to cause false detection. The flow rate was measured for three different reflector number densities at a national standard calibration facility for water flow measurements in Japan. The conditions under which false detection occurred and the influence on the flow rate error were evaluated. The measurement results showed good agreement with the simulation results. In addition, this paper also presents an application of a new signal processing method for UTDC measurements for reducing the rate of false detections caused by the pulse pattern. The experimental results show that this effectively reduces the flow rate error.