LOCAL VELOCITY-MEASUREMENT OF MAGNETIC FLUID-FLOW USING SEMICONDUCTOR-LASER AND OPTICAL-FIBER

A new method is developed, using a semiconductor laser and optical fiber, to measure the local velocity of magnetic fluid flow. In this method, the local flow velocity is obtained by measuring the time taken for a tracer particle to pass between two sets of optical fiber probes. After this method is calibrated with a rotational flow in a rotating channel, it is applied to magnetic fluid flows in an open channel under the influence of a traveling magnetic field which is produced with a stator of a single-sided linear induction motor. As a result, it is clarified that the flows are mainly induced opposite to the traveling direction of the magnetic field and the magnitude of induced velocity is almost proportional to the frequency of the magnetic field, increasing especially near the free surface. The velocity distributions are quite different from those of nonmagnetic fluid flow in an open channel.