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The operation temperatures of gas turbine engines have been increased significantly to optimize their efficiency factor. To protect the metallic blades from these high temperatures, thermal barrier coatings (TBCs) are applied onto the turbine blades. These layers must have a good adhesion to the supporting turbine blade. A poor adhesion may lead to a delamination of the layer during operation and finally to a destruction of the turbine blade and eventually the complete turbine. It is therefore necessary, to check the quality of the layer adhesion regularly during service or preferably during operation. Approaches for non-contact and nondestructive techniques by using optical or infrared radiation are not sophisticated up to now. Hence in this paper a new attempt to improve these optical or infrared-optical methods is described. The presented idea relies on the application of different wavelengths for the used measurement system. Using a short wavelength range, where the TBC is semitransparent, allows the measurement of the temperature of the turbine blade. Using a second, long wavelength range where the TBC is non-transparent, the temperature of the surface of the TBC can be determined. As the thermal contact is usually correlated with the mechanical adhesion such measurements can be a possible tool for nondestructively testing the adhesion of TBCs.
The objective of the EU project “Sensors Towards Advanced Monitoring and Control of Gas Turbine Engines (acronym STARGATE)” is the development of a suite of advanced sensors, instrumentation and related systems in order to contribute to the developing of the next generation of green and efficient gas turbine engines. One work package of the project deals with the design and development of a long wavelength infrared (LWIR) radiation thermometer for the non-contact measurement of the surface temperature of thermal barrier coatings (TBCs) during the operation of gas turbine engines.
For opaque surfaces (e.g. metals or superalloys) radiation thermometers which are sensitive in the near or short wavelength infrared are used as state-of-the-art method for non-contact temperature measurements. But this is not suitable for oxide ceramic based TBCs (e.g. partially yttria stabilized zirconia) as oxide ceramics …
Section 2 of the present paper introduces the two calibration facilities, presents the applied blackbody radiation sources with the achievable uncertainties, the collimator optics, and the climate box. A short introduction of the experimental techniques used and presentation of some experimental results for different camera systems follows in Section 3. A final conclusion is given in Section 4.
Radiometrie im UV und IR
(2009)
Photometrie und Radiometrie
(2007)
The EU project STARGATE (Sensors Towards Advanced Monitoring and Control of Gas Turbine Engines) has the headline objective to develop a suite of advanced sensors, instrumentation and related systems in order to contribute to the development of the next generation of green and efficient gas turbine engines. To increase the efficiency of gas turbines higher combustion temperatures and higher turbine inlet temperatures are required. This implies that turbine blades and vanes are exposed to higher temperatures. Advanced thermal barrier coatings (TBCs) based on ceramic materials protect the components from overheating and ensure mechanical integrity. Still, materials and coatings need to be stressed to their limits to reach the challenging goals of an efficiency increase. Under these circumstances, it is crucial to have sensing techniques available that are capable of accurately monitoring the temperature of turbine parts in order to prevent damages within the engine. The approach to overcome current limitations of existing techniques is to use long wavelength infrared (LWIR) pyrometry as TBCs are usually semi-transparent in the near or short wavelength infrared. Therefore one work package within the STARGATE project is dedicated to the development of a LWIR radiation thermometer to measure the surface temperature of TBCs contactless during operation of the gas turbine engines. The paper shortly gives an overview of the investigation performed within the STARGATE project. The construction, calibration and application of the LWIR radiation thermometer is described in detail and results obtained on a test facility are presented. The paper closes with an outlook on future plans of implementing the LWIR pyrometer in the quality system of gas turbine operation.
Hochtemperaturmessung und Materialuntersuchung für Energietechnik und additive Fertigungsverfahren
(2017)
Practical high-temperature furnace for the application in radiometry, photometry and thermometry
(2008)