| 摘要 |
Provided is a clamp-on type ultrasonic flowmeter capable of accurately measuring a flow rate of fluid. The clamp-on type ultrasonic flowmeter comprises: a first ultrasonic transducer (101) to generate evanescent waves in a wall of a pipe (10) by introducing a first ultrasonic signal into the pipe (10) wherein fluid flows at an angle (&thgr;_wi1) over a critical angle; a second ultrasonic transducer (102) to generate evanescent waves in the wall of the pipe (10) by introducing a second ultrasonic signal into the pipe at the same angle (&thgr;_wi2) as the incident angle (&thgr;_wi1) of the first ultrasonic signal; and a flow rate calculation part (302) to calculate a flow velocity and/or a flow rate of the fluid in the pipe (10) based on a first time until the first ultrasonic signal reaches the second ultrasonic transducer (102) via the pipe (10) and a second time until the second ultrasonic signal reaches the first ultrasonic transducer (101) via the pipe. |
