| 摘要 |
PURPOSE:To reduce measurement errors owing to channeling by disposing plural pairs of transducers in a manner as to intersect obliquely with the flow of fluid, alternately changing over the transmission side and the reception side and driving the transducers disposed on the same side. CONSTITUTION:A transducer 13 is operated as a transmitter by the mode change signal A from a mode selector 109, and the output signal of a transmission circuit 105 is conducted to the transducer 13. The converted output electric signal from a transducer 12 is conducted to the reception circuit. The forward propagation time of the time when ultrasonic pulses are propagated in the forward direction with respect to the flow of fluid 2 after a prescribed time is substituted to the oscillation frequency FA of an oscillator 111, and the measurement in the forward time ends. Next, the transducer 12 is operated as a receiver by the mode change signal B from the selector 109, and the electric signal from the transducer 13 is conducted to a circuit 107. The backward propagation time with respect to the flow V is substituted to the oscillation frequency FB of an oscillator 12. Next, the difference between the frequencies FA and FB is measured and the measured value of the flow speed is determined. |
