| 摘要 |
PURPOSE:To accurately measure the flow rate of an open channel by measuring a flow velocity and a water level at the same time by using an ultrasonic wave, and finding the sectional area of a flow from the value of the water level and integrating the flow velocity. CONSTITUTION:Two couples of ultrasonic oscillators 3 an 4 are installed on the open channel tube 1 and receivers 5 and 6 are provided. At this time, those combinations are set at a constant interval (l) so that ultrasonic waves are reflected by the surface of liquid 2 flowing in the open channel tube 1 and received by the receivers respectively. Then, signals from the receivers 5 and 6 are stored in memories 10 and 11 for a specific time and the pattern contents of the memory 10 are compared by a pattern matching comparator 18 with the contents of the memory 11 while made different in time, but by bit, an the result is outputted to a peak point detector 15. The detector 15 detects the peak point of the comparison result signal to obtain the flow velocity V from the time delay tau up to the peak point. The phase difference phi between the signal from the receiver 5 and the output of an oscillator 7, on the other hand, is detected 18 to obtain the sectional area A of the fluid. Further, the flow rate Q is found from a specific expression and displayed 20.
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