Design of cryogenic flow meter using fiber Bragg grating sensors

This paper describes a novel technique to measure cryogenic fluid flow rate using fiber Bragg grating (FBG) sensors. The proposed design utilizes the drag force caused by fluid flow on the FBG sensor. The strain thus induced in the sensor will cause a Bragg wavelength shift, which can be utilized to estimate the flow rate. Theoretical calculations are done using mathematical models and the design is found to be feasible for a wide range of flow rates and cryogenic temperatures. Calibration experiments are performed for Helium at ambient conditions and the results obtained are regressed to obtain its calibration equation. The sensor shows an overall sensitivity of 20 pm/(g/s) in the range of operation between 0 and 2 g/s and 50 pm/(g/s) in the range of 2 to 5 g/s.