Reference waveform determination method realized by gas ultrasonic flow meter based on cross-correlation time-difference method

Abstract

The invention discloses a reference waveform determination method realized by gas ultrasonic flow meter based on a cross-correlation time-difference method. The measurement principle of the gas ultrasonic flow meter based on the cross-correlation time-difference method is that a signal propagation time difference of two signals is acquired through calculation of a cross-correlation function of ultrasonic receiving signals when gas in a pipeline is in a static state and a flowing state, and then the flow velocity of the gas is determined. When flow measurement is performed, the ultrasonic receiving signals at the same flow velocity have certain randomness due to existence of influence factors such as circuit noise, thermal motion of gas molecules, inconsistency of direct and inverse piezoelectric effects of an ultrasonic transducer and the like. Because of importance of reference waveforms in the aspect of calculation of transit time with a cross-correlation algorithm, the invention provides the reference waveform determination method. According to the method, multiple static waveforms are adopted and averaged, and obtained average waveforms are processed and taken as the reference waveforms. The problem about reference waveform selection when the transit time is calculated with the cross-correlation algorithm is effectively solved, and the measurement precision and repeatability of the transit time are improved.

Description

technical field [0001] The invention belongs to the technical field of ultrasonic flow detection, in particular to a method for determining a reference waveform of a gas ultrasonic flowmeter based on a cross-correlation time-difference method. Background technique [0002] Ultrasonic flowmeter has the advantages of non-blocking flow parts, small pressure loss, suitable for large-diameter pipelines, and can realize bidirectional measurement. It is currently widely used in gas flow measurement. The principle is that when the ultrasonic wave propagates in the fluid, it will be modulated by the fluid, and the propagation speed will contain the flow velocity information of the fluid. When the ultrasonic wave propagates along the fluid flow direction, its propagation velocity will superimpose a component of the fluid flow velocity in the ultrasonic wave propagation direction, resulting in an increase in its propagation velocity; when the ultrasonic wave propagates in the opposite ...

AI Technical Summary

Problems solved by technology

However, due to the circuit noise, the inverse piezoelectric effect of the excitation probe, the repeatability of the piezoelectric effect of the receiving probe, and the thermal motion of gas molecules in the pipeline, there will inevitably be fluctuations and distortions in the waveform of the ultrasonic receiving signal, which will affect the ultrasonic wave. Accurate measurement over time and ultimately affects flow

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