Signal Modeling of Permanent Magnet Sodium Flowmeter With Embedded Vortex Generator Based on Transit Time Series

The permanent magnet sodium flowmeter with embedded vortex generator (PMSF-VG) monitors the liquid metal sodium flow rate in real time in order to ensure the safe operation of the fast neutron reactor. The previous literature studied how to improve the in situ calibration accuracy of the flowmeter from the perspective of signal processing. This article studies this issue from the perspective of signal sources. According to the experimental data, the transit time series is calculated by using the generalized cross correlation method, its characteristics are analyzed, and a moving average (MA) model is established for predicting and improving the accuracy of the in situ calibration. This model is composed of a steady-state component and a fluctuation component. The former reflects the ideal value of the cross correlation flow rate in the in situ calibration and is related to the meter linearity and indication error, which determines the upper limit of the measurement accuracy. The latter determines the repeatability error of the in situ calibration. Aiming at its feature, a two-stage MA filtering method is adopted to reduce the repeatability error of measuring the transit time and improve the accuracy of the in situ calibration.