Improvement of signal-to-noise ratio for Raman distributed temperature sensing on gas turbines

Geunsik Lim; Jeffrey Wuenschell; Gary Lander; Douglas Straub; Michael P. Buric

doi:10.1117/12.2663855

13 June 2023 Improvement of signal-to-noise ratio for Raman distributed temperature sensing on gas turbines

Geunsik Lim, Jeffrey Wuenschell, Gary Lander, Douglas Straub, Michael P. Buric

Author Affiliations +

Proceedings Volume 12532, Optical Waveguide and Laser Sensors II; 125320W (2023) https://doi.org/10.1117/12.2663855
Event: SPIE Defense + Commercial Sensing, 2023, Orlando, Florida, United States

Abstract

To achieve high-efficiency turbine engine operation, turbine combustors must operate with a finely controlled fuel-air ratio near the flame extinction limit, informed by feedback from reliable in-situ temperature measurements. Distributed temperature sensing up to 900-1000 °C using Raman optical-time-domain-reflectometry (ROTDR) with single-crystal optical fiber is demonstrated in a combustion test rig. The distributed temperature sensing (DTS) system utilizes sapphire and yttrium-aluminum-garnet (YAG) fibers which were optimized to improve the signal-to-noise ratio (SNR) of collected Raman signals. Estimation of the SNR of recorded signals and predicted errors were analyzed to simulate the effect of a variety of system parameters and experimental conditions. Enhancement of the SNR through selective doping of the single-crystal fiber was investigated. The expected Stokes and Anti-Stokes collection efficiencies using high-sensitivity avalanche photodiodes were calculated for the optimized optical path. Denoising algorithms of the SNR were developed by exploring noise sources which constrain detection capability via uncorrelated and multiplicative noise. Calibration techniques have been implemented to correct the dynamic variation of the optical loss with temperature in the single-crystal fibers to obtain the calibration parameters and temperature profile.

Citation Download Citation

Geunsik Lim, Jeffrey Wuenschell, Gary Lander, Douglas Straub, and Michael P. Buric "Improvement of signal-to-noise ratio for Raman distributed temperature sensing on gas turbines", Proc. SPIE 12532, Optical Waveguide and Laser Sensors II, 125320W (13 June 2023); https://doi.org/10.1117/12.2663855

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