Reference waveform selection method based on joint of primary and secondary envelopes in cross-correlation method-based gas ultrasonic flowmeter

A reference waveform, ultrasonic technology, applied in liquid/fluid solid measurement, measurement flow/mass flow, measurement device, etc., to achieve the effect of increasing the frequency bandwidth, increasing the difference, and improving the measurement accuracy and repeatability

Inactive Publication Date: 2018-12-18
ZHEJIANG UNIV
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Problems solved by technology

[0004] The purpose of the present invention is to address the deficiencies in the prior art, to provide a reference waveform selection method based on the junction of the primary and secondary envelopes in the cross-correlation gas ultrasonic flowmeter, which can solve the problem of 5 μs stratification of the transit time measurement value and improve Measuring Accuracy and Stability of Gas Ultrasonic Flowmeter by Cross-correlation Time-difference Method

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  • Reference waveform selection method based on joint of primary and secondary envelopes in cross-correlation method-based gas ultrasonic flowmeter
  • Reference waveform selection method based on joint of primary and secondary envelopes in cross-correlation method-based gas ultrasonic flowmeter
  • Reference waveform selection method based on joint of primary and secondary envelopes in cross-correlation method-based gas ultrasonic flowmeter

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Embodiment Construction

[0025] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0026] The present invention provides a method for selecting a reference waveform based on the combination of primary and secondary envelopes in a cross-correlation gas ultrasonic flowmeter. The method includes the following steps:

[0027] 1) When the gas in the pipeline is still (the gas flow rate in the pipeline is 0m / s), use a DSP with a sampling frequency of 6MHz to collect N groups of downstream ultrasonic signals and N groups of upstream ultrasonic signals; in this embodiment, 4 groups of downstream ultrasonic signals are collected. Ultrasonic signal and 4 groups of countercurrent ultrasonic signals, when N is 4, the standard deviation of the calculated value of transit time is the lowest value in the experiment;

[0028] 2) averaging the collected 2N groups of ultrasonic signals in amplitude to obtain an average waveform;

[0029] 3) T...

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Abstract

The invention discloses a reference waveform selection method based on the joint of primary and secondary envelopes in a cross-correlation method-based gas ultrasonic flowmeter. For the problem of 5 [mu]s layering of a transit time calculation value due to use of a traditional reference waveform when the gas flow speed in a pipeline is relatively high, an improved reference waveform selection method is provided. According to the method, a zero crossing point before the inverse fourth wave peak of the primary envelope of an average waveform is used as a starting point; a zero crossing point after the fourth wave peak of the secondary envelope is used as a cutoff point; a waveform between the starting point and the cutoff point is determined as a standard waveform; the rear end of the standard waveform is filled with zero, so that the number of signal points after zero filling is the same as that of collected signal sampling points when the ultrasonic flowmeter works; and a signal waveform after the zero filling of the standard waveform is determined as a reference waveform. According to the method, the problem of the layering of the transit time calculation value is solved, and themeasurement precision and the repeatability of the gas ultrasonic flowmeter are improved.

Description

technical field [0001] The invention belongs to the technical field of ultrasonic flow detection, in particular to a method for selecting a reference waveform based on the combination of primary and secondary envelopes in a cross-correlation gas ultrasonic flowmeter. Background technique [0002] The basic principle of cross-correlation time-difference gas ultrasonic flowmeter is: figure 1 As shown, the upstream transducer transmits the ultrasonic signal, and the downstream transducer receives the ultrasonic signal, and the propagation time of the ultrasonic signal from the upstream transducer to the downstream transducer is measured as the downstream transit time; the downstream transducer transmits the ultrasonic signal , the upstream transducer receives the ultrasonic signal, and the propagation time of the ultrasonic signal from the downstream transducer to the upstream transducer is measured as the countercurrent transit time. The fluid velocity can be calculated by me...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01F1/66
CPCG01F1/66
Inventor 周洪亮汤士桢王艺林
Owner ZHEJIANG UNIV
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