| 摘要 |
PURPOSE:To obtain a measuring apparatus capable of avoiding the sharp increase in pressure loss even when multipoint measurement is performed, by constituting said apparatus of an optical fiber to which a radius of curvature R<=120a (a is the outer diameter of the optical fiber) is applied as initial bending, a light source for allowing light to be incident to said fiber from one end thereof, a photodiode array and an operation part. CONSTITUTION:Lights are guided to an optical fiber network 3, which is constituted of a large number of optical fibers provided in a duct 1 constituting a fluid flow passage ready to measure a flow speed under tension, from one ends of the optical fibers by light sources 2a, 2b and the quantities of the transmitted lights of the optical fibers are detected by the photodiode arrays 4a, 4b provided to the other ends of the optical fibers. A radius of curvature R<=120a is applied to each optical fiber as initial bending. The signals detected by the arrays 4a, 4b, are sent to a transmitted light quantity map operation part 5 and the distribution of the quantities of transmitted lights is operated corresponding to the positions of the fiber crossings on the optical fiber network 3. An average flow speed is operated on the basis of the operated distribution in an average flow speed operation part 6.
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