Fiber Bragg grating sensor for simultaneous measurement of flow rate and direction

Abstract

A new fiber-optic sensor system consisting of a fiber Bragg grating cantilever as a transducer is proposed and demonstrated to realize simultaneous measurement of fluid flow rate and direction. For the fiber Bragg grating mounted on either a stainless steel or a spring steel substrate, a change in the water flow rate gives rise to a monotonic shift in the Bragg resonance wavelength of the grating while the flow direction results in either a redshift or a blueshift in the Bragg wavelength due to a stretched or shrunk state of the grating. Shifts in the Bragg resonance wavelength of 0.077 and 0.826 nm at a water flow rate of 90 cm3 s−1 were achieved with the fiber Bragg grating stainless steel and spring steel cantilever sensors, respectively. The experimental results are in good agreement with the theoretical analysis.