Error Analysis and Accuracy Calibration Method of U-Tube Coriolis Mass Flowmeter Under Pulsating Flow

Abstract

Coriolis mass flowmeter (CMF) is a kind of flow measurement instrument which can directly measure the high precision transient mass flow parameters. And the vibration characteristic of the U-shaped measuring tube inside is one of the important factors that determine the measuring accuracy. The pulsating flow through the measuring tube will lead to the motion component except the main vibration frequency, which will affect the phase difference calculation and reduce the measurement accuracy of the mass flowmeter. This paper presents a method to improve the accuracy of U-tube CMF based on variable step size Least Mean Square (LMS) filter and Hilbert transform with interval-shifting under pulsating flow. Experimental work was conducted on a dynamic experimental platform of pulsating flow. Experimental results show that the stability and accuracy of the proposed algorithm are better than the traditional CMF phase difference calibration method. The mean time difference error is 9.0525μs, and the mean time difference relative error is 5.806%. The calibration effect is more than 88.0934% better than other traditional algorithms. It is verified that it has good error calibration effect for pulsating flow at various frequencies.