Time difference type ultrasonic flowmeter measuring method based on zero point analysis

Abstract

The invention discloses a time difference type ultrasonic flowmeter measuring method based on zero point analysis. The time difference type ultrasonic flowmeter measuring method based on zero point analysis is a method for accurately determining fair-current transmission time and countercurrent transmission time through a zero point analysis method. The time difference type ultrasonic flowmeter measuring method based on zero point analysis comprises the steps that (1) after a pulse drive signal is sent out, an A / D converter is started to conduct data collection; (2) a zero point value is searched; (3) whether a zero point is an ultrasonic signal zero crossing point or not is judged; (4) a first zero crossing point in an ultrasonic receiving signal is selected so that the ultrasonic signal arriving time can be determined and the fair-current transmission time and the countercurrent transmission time can be calculated; (5) instant flow of a section to be measured is calculated through the fair-current transmission time and the countercurrent transmission time. The zero point of the ultrasonic signal is not influenced by the external environment, the zero point can be detected even under the conditions that the signal is weak, fluctuation is large and interference is strong, the fair-current transmission time and the countercurrent transmission time of the ultrasonic signal in fluid can be accurately measured, the measuring accuracy of a time difference type ultrasonic flowmeter is greatly improved, and the problems brought by an existing threshold value comparing method are thoroughly solved.

Description

technical field [0001] The invention relates to an ultrasonic flowmeter measurement method, in particular to a time-difference ultrasonic flowmeter measurement method based on zero-point analysis. Background technique [0002] Ultrasonic flowmeter has no moving parts and can realize non-contact high-precision measurement. It has the advantages of wide range, no pressure loss, good traceability, and cost insensitivity to caliber changes. It can be used to measure round pipes, square culverts, open channels, etc. The measurement of liquid or gas flow in the section has obvious advantages, especially in the flow measurement of medium and large pipe diameters. [0003] Ultrasonic flowmeter has been developed so far. Among many measurement methods, transit-time ultrasonic flowmeter has the advantages of simple measurement method and high measurement accuracy, and has always attracted attention. The principle of the time-difference ultrasonic flowmeter is to calculate the flow ve...

AI Technical Summary

Problems solved by technology

[0014] ②If the ultrasonic receiving signal becomes too weak and the maximum amplitude is below the threshold, the propagation count will overflow and the accurate propagation time cannot be measured, such as figure 2 as shown in (c);

[0015] ③If the ultrasonic receiving signal fluctuates, the threshold voltage will drift with the receiving signal cutting time point for the first time, resulting in inaccurate measurement of propagation time, thus affecting the dynamic measurement accuracy of the transit-time ultrasonic flowmeter

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