| 摘要 |
PROBLEM TO BE SOLVED: To provide a method of measuring a flow rate and an ultrasonic flowmeter which can measure the flow rate of fluid with accuracy, using frequency with which the phase difference becomes 0. SOLUTION: The ultrasonic velocity of a standard state used as criterion of fluid is provided, ultrasonic waves are made to be transmitted from one side into a flowing fluid in a tube 10, the ultrasonic waves are received by the other side, and the ultrasonic speed A at that time is measured. The ultrasonic wave is made to transmit from the other side into flowing fluid in the tube, the ultrasonic waves are received by the one side, and the ultrasonic speed B at that time is measured. The average value of the ultrasonic speed A and the ultrasonic speed B is computed, and the absolute speed of the ultrasonic waves in the fluid is detected, the flow rate V of the fluid is detected, by dividing the difference of the ultrasonic speed A and the ultrasonic speed B by 2; the flow rate V of the fluid is detected; the exact flow rate of the fluid is detected, by compensating the flow rate V from the misalignment of the ultrasonic velocity of the standard state; the absolute speed, the exact flow rate of the fluid is detected; and the fluid flow of the fluid is measured from this exact flow rate and the cross section in the tube. COPYRIGHT: (C)2007,JPO&INPIT
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