Calculation and Matching of Correction Frequency Band in In Situ Calibration of Permanent Magnet Sodium Flowmeter Without Vortex Generator

In order to reduce the nonlinearity error in the in situ calibration of the permanent magnet sodium flowmeter without vortex generator (PMSF-wVG) and optimize the electrode spacing configuration of the sensor, first, the correction frequency band is calculated more accurately according to the amplitude–frequency characteristics (AFC) of the cross power spectral density (CPSD) so that the signals in this band can be used for nonlinearity correction, making the calculated cross correlation flow rate close to the standard flow rate. Second, for the sake of matching the correction frequency band, multiple pairs of cross correlation electrodes are added to the PMSF-wVG. The quantitative relationship between the spacing between the cross correlation electrodes whose signals subtract in the same direction and the signal attenuation band after subtracting is given, so as to link the electrode spacing with the attenuation frequency band. Moreover, the goal of the attenuation frequency band is to converge to the correction frequency band, so the electrode spacing can be adjusted to match the correction band for improving the accuracy of the in situ calibration of the PMSF-wVG.