Magnetic Coupling of Two Coils Due to Flow of Pure Water Inside Them – Double Coil Volumetric Flow Sensor

In this work a simple new type of flow sensors was developed; the double coil flow sensor. In this sensor two coils are magnetically coupled due to the flow of pure water inside them. The first coil, the primary coil, was supplied by AC voltage in the frequency range 0.5-1 MHz which is the coupling range of frequency for water. The voltage in the second coil, was found to be directly proportional with the volumetric flow rate of the water flowing inside the coils. The two coils can only be coupled in the laminar flow region. In the turbulent region, due to the turbulent chaos and fluctuation the two coils cannot be effectively coupled, and therefore the sensor cannot be used. The temperature of the water was found to have a negligible effect on the coupling, which add a good advantage to the simplicity of the double coil sensor. The working fluid used in this work was pure water. Other fluids are believed to be working as well, most probably at different frequency range, and this will be the subject of future work.