Bare Fiber Bragg Grating Sensor Research Articles

Measurement of temperature and pressure on the surface of a blunt cone using FBG sensor in hypersonic wind tunnel

Measurement of temperature and pressure exerted on the leeward surface of a blunt cone specimen has been demonstrated in the present work in a hypersonic wind tunnel using fiber Bragg grating (FBG) sensors. The experiments were conducted on a 30° apex-angle blunt cone with 51 mm base diameter at wind flow speeds of Mach 6.5 and 8.35 in a 300 mm hypersonic wind tunnel of Indian Institute of Science, Bangalore. A special pressure insensitive temperature sensor probe along with the conventional bare FBG sensors was used for explicit temperature and aerodynamic pressure measurement respectively on the leeward surface of the specimen. computational fluid dynamics (CFD) simulation of the flow field around the blunt cone specimen has also been carried out to obtain the temperature and pressure at conditions analogous to experiments. The results obtained from FBG sensors and the CFD simulations are found to be in good agreement with each other.

Method for Enhancing and Controlling Temperature Sensitivity of Fiber Bragg Grating Sensor Based on Two Bimetallic Strips

This paper presents a novel structure based on bimetallic strips for enhancing temperature sensitivity of fiber Bragg grating (FBG) sensors. Two different types of sensor heads have been designed for this implementation. The first sensor head consists of an FBG that is fixed between ceramic block on one side and a bimetallic strip made up of aluminum and copper on the other. The second sensor head consists of an FBG that is fixed between two bimetallic strips. Theoretical and experimental studies carried out on these proposed sensor heads resulted in an increase in temperature sensitivity of about six times greater than that of bare FBG sensor. Further, the proposed sensors have shown good linearity and stability.

Electroless Nickel Plating and Electroplating on FBG Temperature Sensor

Abstract Metal-coated fiber Bragg grating(FBG) temperature sensors were prepared via electroless nickel(EN) plating and tin electroplating methods on the surface of normal bare FBG. The surface morphologies of the metal-coated layers were observed under a metallographic microscope. The effects of pretreatment sequence, pH value of EN plating solution and current density of electroplating on the performance of the metal-coated layers were analyzed. Meanwhile, the Bragg wavelength shift induced by temperature was monitored by an optical spectrum analyzer. Sensitivity of the metal-coated FBG(MFBG) sensor was almost two times that of normal bare FBG sensor. The measuring temperature of the MFBG sensor could be up to 280 °C, which was much better than that of conventional FBG sensor.