| Abstract | Gas turbine engines produce thrust or power by expanding hot gases generated by burning fuel. Therefore, it is very important to measure and monitor temperature accurately in order to control and protect the engine. In particular, for advanced gas turbine engines, accurate temperature measurement in hot sections such as the combustor and turbine become increasingly important since demands for higher efficiency and more stringent emission targets drive their operation closer and closer to established limits. The ability to measure temperature under such harsh environments is currently restrained by the lack of sensors and controls capable of withstanding the high temperature, pressure and corrosive conditions present. Thermocouples are most commonly used due to their low cost and simplicity, but where steep temperature gradients exist, their slow response and instrumentation complexity demand alternative solutions. Femtosecond infrared (fs-IR) written fiber Bragg grating (FBG) sensors have inherent advantages over thermocouples for rapidly measuring high resolution temperature profiles under harsh conditions. Perhaps the greatest benefit of fs-IR FBG sensors is their quasi-distributed sensing capability, with many sensors deployable in such environments, along a single optical fiber filament. This paper presents the results of experimental studies to compare the measurement performance between a thermocouple rake and fs-IR FBG temperature probes for the combusted gas temperature at the combustor exit plane which has stiff temperature gradients. In addition, preliminary results of wall temperature measurement using fs-IR FBG sensors at the combustor wall will be presented. Along with the experimental comparison, this paper will include the pros and cons of FBG sensors, discussion of deployment strategies, as well as comments on reliability and other important considerations. |
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