A metalized and regenerated fiber Bragg grating temperature sensor with spectral self-repair ranging from −50 ℃ to 600 ℃

Abstract

In this study, we developed a metalized and regenerated fiber Bragg grating (RFBG) temperature sensor with a spectral self-repairing function, aiming to measure both high and low temperatures for aircraft engine exhausting jet. The designed sensor consists of a metal substrate with an S-shaped groove, one fiber Bragg grating (FBG), and two welded sheets connected by laser welding. The high-temperature regeneration process improves the high-temperature measurement range of the sensor. In addition, an algorithm of discrete wavelet transform and Gaussian model iteration (DWT-GMI) for solving spectral degradation at low temperatures is proposed. Simulation analyses of the spectral degradation are performed to verify the feasibility of the proposed algorithm. The simulation results show that the root mean square error (RMSE) between the repaired wavelength and the actual wavelength is 0.0436. The temperature calibration experiment is conducted for different bonding methods, including AB adhesive, tin welding, and laser welding. The linear correlation coefficient of the RFBG sensor of laser welding is 0.99919, the sensitivity is 15.64 pm/℃, and the measurement range is −50 ℃ to 600 ℃, which is larger than the other two bonding methods. The accelerated life experiment is completed to predict the service life of the designed sensor according to the Arrhenius model. The above advantages enable the designed sensor suitable for air jet temperature monitoring for aircraft engines.