Non-invasive fluid flow sensing based on injected heat tracers and indirect temperature monitoring

摘要

A system and method for measuring flow rate within a fluid-bearing passageway include introducing heat fluctuations into the flow and then non-invasively monitoring the effects of the heat fluctuations propagating to or from one or more interrogation regions. In one embodiment, the non-invasive monitoring detects fluctuations in the refractive index of the flowing fluid as a result of variations in the temperature of the fluid. In another embodiment, electrical conductivity of the fluid is monitored. The heat fluctuations may be introduced using an optical heat generator, such as an infrared laser, or may be introduced using an electrical member, such as a heater coil. Determining the refractive index along the interrogation region may be achieved by monitoring characteristics on an interference pattern, but other optical arrangements may be utilized.