| 摘要 |
Reliability of bubble or particle detection in a flowing fluid is improved using a pulsed doppler frequency detector. When an echo signal is received, impliedly indicating the existence of a bubble or particle in the carrier fluid, then, based on the flow rate of the carrier fluid, a predetermined time interval is established following a second interrogating pulse during which the second interrogating pulse would be predicted to produce an echo if the first echo did, in fact, represent a real bubble or particle in the fluid. Detection of the second echo during this time interval confirms the existence of the bubble or particle. For fluid flows with cross section velocity profiles that are not constant, e.g. laminar flow, a plurality of different predicted time intervals are established for different points in the velocity profile spaced radially from the fluid conduit and multiple sensing cycles are employed to thereby detect bubbles or particles at different radial positions in the fluid cross section.
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