| 摘要 |
An apparatus for measuring the flow velocity by detecting the number of Von Karman's vortex streets or Strouhl vortexes by utilizing heating wires, said apparatus comprising a vortex generator disposed in a fluid to be measured, at least one heat-sensitive element which detects the flow velocity or flow rate of the fluid in the form of change of temperature caused by said vortex generator, and which produces detection signals that represent change in frequency of the electric signals, an operational amplifier for amplifying the detection signals, and a feedback circuit which feeds the output of said operational amplifier back to said heat-sensitive element such that its temperature is maintained substantially constant, and such that the preset temperature of said heat-sensitive element changes in response to the output of said operational amplifier, whereby the frequency characteristics thereof are improved and the apparatus can be stably started under any conditions. |
