Ultrasonic transit time calculation method based on envelope feature points of cross-correlation function

A cross-correlation function and transit time technology, applied in measurement devices, instruments, measurement flow/mass flow, etc., can solve problems such as drift, transit time value deviation, etc., achieve strong anti-interference ability, improve accuracy and repeatability sexual effect

Inactive Publication Date: 2019-02-01
ZHEJIANG UNIV
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Problems solved by technology

However, as the gas flow rate increases, the received waveform will be distorted under the action of the flow field and noise. Since the amplitude discrimination between the maximum value of the cross-correlation function and the maximum value of adjacent waves is very small, it is easy to cause The maximum point of the cross-correlation function drifts between adjacent peaks, causing a large deviation in the transit time value

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  • Ultrasonic transit time calculation method based on envelope feature points of cross-correlation function
  • Ultrasonic transit time calculation method based on envelope feature points of cross-correlation function
  • Ultrasonic transit time calculation method based on envelope feature points of cross-correlation function

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[0021] refer to figure 1 , the overall process of the present invention includes two stages of modeling and calculation, within the range, according to the form of the gas flow field (laminar flow, transitional flow and turbulent flow) and taking into account each flow velocity section (low flow velocity ≤ 5m / s, middle flow velocity 5m / s -10m / s and high velocity ≥10m / s) select 12 velocity points as velocity points for modeling. Specifically, according to the definition of Reynolds number and taking into account the entire range, the following 12 flow velocity points are determined as the flow velocity points for modeling, 0m / s, 0.2m / s, 0.4m / s, 1.0m / s, 2.5m / s , 5.0m / s, 7.5m / s, 10.0m / s, 15.0m / s, 20.0m / s, 25.0m / s, 30.0m / s.

[0022] refer to figure 2 , select a part of the receiving signal waveform at zero flow rate as the reference waveform (the starting point is close to the ultrasonic wave starting point), and continuously collect 200 ultrasonic receiving signal waveforms at...

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Abstract

The invention discloses an ultrasonic transit time calculation method based on envelope feature points of a cross-correlation function. The traditional ultrasonic transit time adopts the cross-correlation method, and calculates the transit time by using the maximum value of the cross-correlation function as the feature points. However, as the gas flow rate increases, the ultrasonic wave receivingwaveform will be distorted, causing the position of the maximum value of the cross-correlation function to drift at the same flow rate, and it is difficult to obtain an accurate transit time value. The invention proposes a new transit time calculation method by analyzing a large number of cross-correlation function waveforms. The method comprises: performing extremum extraction and normalization of each cross-correlation function waveform; finding the two maximum points where the difference between adjacent maxima is the largest; determining a feature point between two maximum points; calculating the transit time value by the feature point in the calculation. The experimental results show that the method overcomes the problem of small amplitude difference between the maximum value and theadjacent maximum value of the traditional cross-correlation algorithm, and improves the accuracy of the transit time calculation.

Description

technical field [0001] The invention belongs to the technical field of gas ultrasonic flow detection, in particular to a method for calculating transit time based on a cross-correlation algorithm. Background technique [0002] With the implementation of the "West-to-East Gas Transmission" strategy and the "Coal to Gas" project, natural gas occupies an increasing proportion in my country's energy structure. Gas ultrasonic flowmeter occupies a pivotal position in natural gas metering due to its advantages of no obstructed flow parts, no moving parts, suitable for large pipe diameter measurement and bidirectional measurement. Compared with the relatively mature gas ultrasonic flowmeter technology abroad, domestic technology in this field started late, and there is a big gap in gas flow characteristics, flow field distribution, channel layout and integration algorithm. High-end gas ultrasonic Flow meters still rely on imports. For this reason, many domestic scientific research...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01F1/66
CPCG01F1/66
Inventor 王艺林周洪亮刘焱矗
Owner ZHEJIANG UNIV
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