| 摘要 |
A target-type flow meter uses a target in a flowing fluid and selectively changes the orientation of the target with respect to the direction of flow of the fluid between two or mote orientations, where the target provides a different flow impedance in each of the orientations. This change in flow impedance gives rise to a corresponding difference in drag forces exerted on the target by the flowing fluid. Those forces, or displacements associated with them, are measured to determine the rate of fluid flow. In some cases the target may be a vane attached to a shaft rotated by a motor. In others, the target may be a vane structure attached to a post in a flexible fashion so that it can be oscillated transverse to the flow direction by fixed electromagnets acting on a permanent magnet portion of the vane structure.
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