Flow rate measurement method, ultrasonic flow rate meter, flow velocity measurement method, temperature or pressure measurement method, ultrasonic thermometer and ultrasonic pressure gage

摘要

An flow rate measurement method and a ultrasonic flow meter is provided, which can measure a flow velocity accurately by utilizing a ultrasonic wave having a frequency by which a phase difference becomes zero. According to the flow rate measurement method, a reference ultrasonic velocity is prepared such that the fluid is in a standard condition, firstly. Then, an absolute ultrasonic velocity in the fluid and a temporary flow velocity V0 in the fluid are obtained. Then, the temporary flow velocity V0 is corrected by using the difference between the reference ultrasonic velocity and the absolute ultrasonic velocity thereby to determine an accurate flow velocity of the fluid, and to determine a flow rate of the fluid by using the accurate flow velocity and a cross section area of the conduit.