Estimation of velocity profile by magnetic flowmeter with rotating field

Magnetic flowmeters have been one of the standard meters to measure liquid flowrate. Since it has been proved to be impossible to design the exciting magnetic fields that induce the flow signal proportional to volumetric flowrate free from the flow profile, it is possible to measure and/or to evaluate flow profiles through the proper design of the magnetic field, conversely. This paper describes the trial to extend the application field of magnetic flowmeter and to study the feasibility of the flow profile measurement under the rotating magnetic field. Two-dimensional case is treated for the simplicity. It is concluded that the two-dimensional flow profile can be partially reconstructed from periods of the signal picked up at a pair of point electrodes under the rotating field. Since the reconstruction is confined around the neighbor of the electrodes, both the exciting magnetic field and the configuration of the signal pick-up electrodes must be varied.