摘要 |
Described are systems for measuring the rate of fluid flow wherein the time delay between acoustic pulses transmitted upstream and downstream in a fluid passing along a path of travel is multiplied by repeated transmissions in sing-around fashion. The systems of the invention have the advantage of fast response time, but do not require the measurement of very small time differences, particularly at low velocities, because of the cumulative effect of combing the time delays between upstream and downstream pulses over a period of time. |