| 摘要 |
PROBLEM TO BE SOLVED: To provide an ultrasonic device for measuring core flow rate and an ultrasonic flowmeter having an excellent SN ratio, and a comparatively small operation processing amount. SOLUTION: A plurality of ultrasonic transmission/reception units 10 are installed on the surface of a reactor pressure vessel 3 through which a fluid passes, and a timing when an ultrasonic wave is to be propagated into the fluid is controlled by an ultrasonic transmission/reception controller 201, and a cross spectrum is calculated from two signals on the upstream and the downstream relative to an ultrasonic wave propagating in the fluid by a cross spectrum computing unit 204. Then, a coefficient for calculating analytically a mutual correlation coefficient of the two signals is extracted from the cross spectrum calculated by a time difference computing unit 206, and the maximum peak arrival time of the mutual correlation waveform in a time domain set beforehand is calculated by using the extracted coefficient, and a flow rate of the fluid is calculated. COPYRIGHT: (C)2009,JPO&INPIT
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