| 摘要 |
<p>An ultrasonic flow meter (110) using ultrasonic pulses transmitted within a pipe (150) containing flowing fluid determines values, including flow rate or velocity of the fluid. The pulses having velocity components either in the upstream or downstream direction. The meter (110) includes a downstream transducer (140), an upstream transducer (130) and an electronics (120) is connected to the transducers (130, 140) which are placed external to the pipe (150). The electronics (120) comprises a logic switch (220), a high voltage converter (230), a miltiplexor (240), an amplifier (250), a comparator (260), and a processor (210) having a timer (210a), a counter (210b) and a memory (210c). Time measurements are made to determine a time, TU, required for a pulse train to travel from the transducer (140) to the transducer (130) and a time, TD, required for a pulse train to travel from the transducer (130) to the transducer (140). Once TU and TD are determined, either a series of validation filters, parameter filters, coarse flow rate filters and refined flow rate filters, or fluid velocity filters are used to determine flow measurement. Also, diameter filters are used to determine the current interior diameter of the pipe (150). The system and method includes determining coefficients for the filters to account for variability in dimensions, parameters and conditions involved.</p> |
