High-Density Fiber Optical Sensor and Instrumentation for Gas Turbine Operation Condition Monitoring

Abstract

Gas turbine operation control is normally based on thermocouple-measured exhaust temperatures. Due to radiation shielding and bulky package, it is difficult to provide high spatial resolution for measuring can-to-can combustion temperature profile at the exhaust duct. This paper has demonstrated that wavelength-division-multiplexing-based fiber Bragg grating sensors could provide high spatial resolution steady and dynamic temperature measurements. A robust sensor package can be designed with either circumferential sensing cable or radial sensing rake for quasi-distributing multiple fiber sensors in the gas turbine environment. The field validations have demonstrated that quasi-distributed fiber sensors have not only demonstrated its temperature measurement accuracy compared to existing thermocouple sensors but also shown its unique dynamic response amplitude and power spectra that could be utilized for gas turbine transient operation condition monitoring and diagnostics.