| 摘要 |
In a method of measuring the flow velocity of a suspension by ultrasonic echo pulse technique, two or several ultrasonic transducers, located at a distance from each other, are placed on the surface of the pipe conducting a suspension flow. An ultrasonic pulse is transmitted from the transducers through the pipe and an echo of the ultrasonic pulse is received after a time determined by the depth of the suspension. The echo pulses are received, and a low frequency signal contained in such pulses, caused by fibres or other particles in the suspension, is amplitude-detected. A second, or later, echo from the opposite wall of the pipe is utilized if a received echo is masked by the transmitted pulse. The signals derived from the transducers are compared by correlation and the flow velocity of the suspension to be measured is thus determined. The second echo from the opposite wall of the measuring pipe is preferably used. The ultrasonic pulse is delivered from the transducer perpendicularly against the opposite wall of the pipe and is reflected back to the transducer side of the pipe when it is reflected again back to the opposite side and once again reflected to the transducer. |
