| 摘要 |
A fluid velocity measurement system includes a thermal generation means operated for short durations of time and disposed within a conduit suitable for guiding at least a portion of a fluid whose velocity is to be determined. Disposed downstream in the fluid guide means is at least one of a first and second thermal sensing means. The sensing means are spaced from each other. The first and second thermal sensing means are differentially coupled. The time period starting with the thermal generation means being turned on and heating a slug of fluid and extending to the generation of a differential electrical signal from the sensing means detecting the heated slug of fluid is the flight time of the heated slug of fluid. In one embodiment of the invention circuitry is provided to measure the actual flight time and divide it into a predetermined period of time resulting in a quotient which is proportional to the fluid velocity. In another embodiment the flight time is measured by a count which is divided into a predetermined count which is equivalent to a quotient also proportional to the fluid velocity. Both embodiments further include means for receiving the quotient and converting it into an appropriate signal to operate a numerical display.
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