Multipoint Temperature Measurement System for Aero-Engine External Piping Based on Arrayed Fiber Bragg Grating Temperature Sensors

The fire resistance of external pipelines in aero-engines is of significant importance for enhancing engine reliability. Conventional electrical sensors face limitations in measuring fluid space temperature fields. Aiming at resolving this shortcoming, the present study introduces an arrayed fiber Bragg grating sensor (AFBGS) that achieves a 3-cm temperature spatial resolution under 60-cm piping during fire resistance tests, enabling real-time and continuous monitoring. AFBGS employs a special packaging technique for high sensitivity and fast response time, adopts the stress-free parallel band method (SFPM) to address cross-sensitivity issues, and includes a specially designed stop ring to reduce the influence of cyclic vibration of fluid flow on AFBGS. Experimental results demonstrate the AFBGS’ temperature sensitivity of approximately
$1.2\times 10^{-{2}}$
nm/°C, with good linearity and repeatability, and a maximum temperature measurement error of approximately ±1 °C. The temperature gradients along the fluid flow direction during tests exhibit a maximum of 2.7 °C at 200 °C. This article demonstrates that the developed AFBGS is an accurate tool for measuring temperature gradients during fire tests, providing insights into actual piping operating conditions and safety assessments.