Flow sensor using optical fibre strain gauges.

Schmitt, N. F. and Morgan, R. and Chandy, R. P. and Scully, P. J. and Lewis, E. (1995) Flow sensor using optical fibre strain gauges. Proceedings of SPIE, 2508 (266). pp. 266-276. ISSN 0277-786X

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A novel technique for the measurement of air flow velocity using an optical fiber sensor is reported. The sensor measures the deformation of a rubber cantilever beam when subjected to the stresses induced by drag forces in the presence of the airflow. Tests performed in a wind tunnel have indicated a sensitivity of 2 (mu) /(m/s). A qualitative model based on fiber mode propagation has been developed which allows the sensor to be characterized in terms of optical losses. A single 1 mm diameter polymer fiber is mounted on the rectangular section rubber cantilever (section 14 mm by 6 mm) and six grooves are etched into the fiber which extend into the core of the fiber. As the beam deviates the surface deforms (stretches or contracts) and the fiber is subjected to strain. As the strain is increased the grooves become wider and the amount of light transmitted through the fiber is reduced due to increased losses. The sensor described has all the advantages of optical fiber sensors including electrical noise immunity and intrinsic safety for use in hazardous environments. However, its simple construction, robustness, versatility for a number of different fluid applications, as well as relatively low cost make it attractive for use in a wide variety of measurement applications e.g. wind velocity measurement where airborne moisture or chemicals are present.

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Proceedings of SPIE
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18 Dec 2008 09:43
Last Modified:
22 Sep 2023 00:00