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To address the needs for increasing efficiency in power conversion, stratified structures like thermal barrier coatings, are used to increase operation temperature. Also advanced material processing like 3D laser printing of metals and ceramics are based on a layer-to-layer process at high temperatures, resulting in non-homogeneous components. Both systems require more and more detailed investigation methods to characterise the material properties of the resulting structures and to optimize the relevant processes. To address the required needs in advanced material characterisation recently an attempt was started to develop a unique measurement set-up for advanced material characterisation. This method is based on the well know laser flash principle, which was improved by adding supplementary heating sources and additional detection channels. Combining different heating mechanism and heating times with the two-dimensional measuring of the thermal flow across the sample enables the determination of different opto-thermal parameters and other material properties, e.g. mechanical contact, electrical conductivity or optical data, which also depend on or affect the flow of heat. In this paper we describe the implementation of the different optical methods to measure the thermal heat flow by point-like and two-dimensional temperature measurement and present first results on several samples.
Development of Long Wavelength Infrared Radiation Thermometry for Measurements in Gas Turbines
(2016)
Ein Versuch zur berührungslosen nicht-invasiven Qualifizierung der Haftung von Wärmeschutzschichten
(2017)
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 …
Stationary gas turbines are still an important part of today's power supply. With increasing temperature of the hot combustion gas inside a gas turbine, the efficiency factor of the turbine increases. For this reason, it is intended to operate turbines at the highest possible gas temperature. Therefore, in the combustion chamber and especially at the position of the first stage guide vanes the gas temperature needs to be measured reliably. To determine the gas temperature, one promising approach is the application of a non-contact measurement method using a radiation thermometer. A radiation thermometer can measure the gas temperature remotely from outside of the harsh environment. At ZAE Bayern, a high temperature and high pressure gas cell has been developed for this purpose in order to investigate gases and gas mixtures under defined conditions at high pressures and high temperatures. This gas cell can …
Berührungslose Temperaturmessung an Verbrennungsgasen bei hohen Temperaturen und hohen Drücken
(2019)
Stationäre Gasturbinen sind von großer Bedeutung für die heutige Energieversorgung. Der Wirkungsgrad einer Gasturbine steigt mit zunehmender Heißgastemperatur an. Turbinenhersteller bzw. Kraftwerksbetreiber sind daher bestrebt, Turbinen bei der höchsten materialtechnisch möglichen Heißgastemperatur einzusetzen. Eine entsprechende Prozessoptimierung des Turbinenbetriebs setzt somit die exakte Kenntnis der Gastemperaturen während des Betriebs und damit eine verlässliche Messung derselben voraus. Zur Messung der Gastemperatur werden derzeit in der Regel Thermoelemente unmittelbar im Abgasstrom platziert. Aufgrund der dort vorherrschenden extremen Bedingungen degradieren diese Sensoren allerdings sehr schnell. Ein alternativer Ansatz sieht die Entwicklung eines berührungslosen Messverfahrens auf der Grundlage von Strahlungsthermometern vor. Für die Umsetzung dieses Vorhabens ist die genaue Kenntnis des Verhaltens der infrarot-optischen Emissions- und Transmissionsspektren der im Abgasstrom enthaltenen Gase bei hohen Temperaturen und Drücken eine wesentliche Voraussetzung. Aus diesem Grund wurde am ZAE Bayern eine Hochtemperatur-Hochdruck-Gaszelle entwickelt, die es in Verbindung mit einem FTIR-Spektrometer erlaubt, Gase und Gasgemische hinsichtlich dieser Gesichtspunkte zu charakterisieren. In dieser Arbeit wird die neue Messapparatur vorgestellt und Gasgemische, die für die Turbinenanwendungen relevant sind, werden analysiert. Zur Identifizierung eines geeigneten Wellenlängenbereichs für die geplante berührungslose Temperaturmessung wurden erste Messungen durchgeführt, auf deren Grundlage ein adäquater Wellenlängenbereich ermittelt werden konnte.
Energy efficiency and operation safety in energy conversion, process technology, and aerospace engineering requires advanced material investigation, in particular at high temperatures to characterize the materials and components. Additionally, modern additive manufacturing methods, in particular the 3D metal laser printer requires a detailed control of the melting temperature. Many applications are based on a layered structures, e.g. thermal barrier coatings in gas turbines. Also components manufactured by additive manufacturing pose a layered structure. In these structures the mechanical contact between the layers and to the substrate is of high interest. Besides, the complete characterisation of the additive manufactured component is important for its later application. To cope with these new demands, the University of Applied Sciences Wuerzburg - Schweinfurt (FHWS) and the Bavarian Center for Applied …
Das Ziel dieser Arbeit bestand in der Entwicklung eines langwelligen Strahlungsthermometers zur berührungslosen Messung von Oberflächentemperaturen in stationären Gasturbinen während des Betriebs der Turbinen innerhalb des EU-geförderten Projektes „Sensors Towards Advanced Monitoring and Control of Gas Turbine Engines (Acronym STARGATE)“. Im Rahmen der Arbeit wurden die infrarot-optischen Eigenschaften der Wärmedämmschichten und der vorhandenen Brenngase am ZAE Bayern bei hohen Temperaturen bis 1600 K und Drücken bis 13 bar bestimmt. Mit Hilfe dieser experimentellen Charakterisierungen konnte ein geeigneter Spektralbereich um 10 μm für das langwellige Strahlungsthermometer identifiziert werden. Entsprechend dieser Erkenntnisse wurde zunächst ein Laboraufbau mit geeigneten optischen Bauteilen (Filter, IR-Wellenleiter, etc.) realisiert und verifiziert. Anschließend wurde ein Prototyp für Messungen in Gasturbinen während des Betriebs der Turbinen entwickelt und in einem Turbinenteststand der Firma Siemens AG in Berlin erfolgreich getestet. Abschließend wurde eine Unsicherheitsanalyse durchgeführt, die eine erweiterte Messunsicherheit der gemessenen Temperaturen von etwa ± 30 K ergab.
A collection of slides from the author's conference presentation is given. The presentation introduces the infrared-optical characterization of thermal barrier coatings and the development of LWIR pyrometer for measuring temperature in an operating gas turbine. The test facility for evaluating the LWIR pyrometer is also presented. This presentation includes the experimental setup for LWIR calibration and measurement.
In the context of the optimization of stationary gas turbines, the surface temperatures of the turbine blades have to be measured by a non-contact technique using radiation thermometers during operation of the turbine. Nowadays turbine blades are protected by thermal barrier coatings. The infrared-optical properties of these coatings require the usage of the MIR or LWIR region for non-contact measurement of the surface temperatures. For performing such measurements and for properly analyzing the derived data, the transmission and absorption spectra of the combustion gas mixture within the turbine were determined at the local conditions during operation of the turbine. Therefore, subject of this work is the measurement of the transmission spectra of carbon dioxide and water vapor at high temperatures and high pressures to identify a wavelength range, which is almost free of absorption and emission effects. In …
An improved apparatus for measuring the spectral directional emissivity in the wavelength range between 1 µm and 20 µm at temperatures up to 2400 K is presented in this paper. As a heating unit an inductor is used to warm up the specimen, as well as the blackbody reference to the specified temperatures. The heating unit is placed in a double-walled vacuum vessel. A defined temperature, as well as a homogenous temperature distribution of the whole surrounding is ensured by a heat transfer fluid flowing through the gap of the double-walled vessel. Additionally, the surrounding is coated with a high-emitting paint and serves as blackbody-like surrounding to ensure defined boundary conditions. For measuring the spectral directional emissivity at different emission angles, a movable mirror is installed in front of the specimen, which can be adjusted by a rotatable arrangement guiding the emitted radiation into the attached FTIR-spectrometer. The setup of the emissivity measurement apparatus (EMMA) and the measurement procedure are introduced, and the derived measurement results are presented. For evaluating the apparatus, measurements were performed on different materials. The determined emissivities agree well with values published in literature within the derived relative uncertainties below 4% for most wavelengths.
Non-Contact Temperature Measurement Of Combustion Gases at High Temperatures and High Pressures
(2016)
Development of Long Wavelength Infrared Radiation Thermometry for Measurements in Gas Turbines
(2016)
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.
