Application of multispectral radiation thermometry in temperature measurement of thermal barrier coated surfaces

Measurement ◽  
2016 ◽  
Vol 92 ◽  
pp. 218-223 ◽  
Author(s):  
Ketui Daniel ◽  
Chi Feng ◽  
Shan Gao
Keyword(s):  
Temperature Measurement ◽  
Radiation Thermometry ◽  
Thermal Barrier ◽  
Coated Surfaces ◽  
Multispectral Radiation Thermometry

Experimental Investigation of Emissivity of Aluminum Alloys and Application of Multispectral Radiation Thermometry

2010 ◽  
Author(s):  
Chang-Da Wen
Keyword(s):  
Aluminum Alloys ◽  
Temperature Measurement ◽  
Radiation Thermometry ◽  
Surface Oxidation ◽  
Spectral Emissivity ◽  
Absolute Temperature ◽  
Real Surface ◽  
Emissivity Model ◽  
Higher Temperature ◽  
Multispectral Radiation Thermometry

Experiments were first conducted to measure the spectral normal emissivity values of a variety of aluminum alloys at 600, 700, and 800 K. Multispectral radiation thermometry (MRT) using linear emissivity models (LEM) and log-linear emissivity models (LLE) were then applied to predict surface temperature. Results show that the spectral emissivity decreases with increasing wavelength and increases with increasing temperature. Alloy effect becomes evident at higher temperature. The surface oxidation becomes fully-developed after the first hour heating and results in constant emissivity. Half of temperature predictions by MRT emissivity models provide the absolute temperature error under 10% and a quarter if the results are under 5%. The better emissivity model to suitably represent the real surface emissivity behaviors the more accurate inferred temperature by MRT can be achieved. Increasing the order of emissivity model and increasing the number of wavelengths cannot improve temperature measurement accuracy. More accurate temperature measurement by MRT can be achieved at higher temperature. Overall, three emissivity models give good results most frequently and provide the best compensation for different alloys, the number of wavelengths, and temperatures.

Detection method of combustion oscillation characteristics under strong noise background

2020 ◽  
Vol 21 (6) ◽  
pp. 612
Author(s):  
Yunkun Wei ◽  
Tianhong Zhang ◽  
Zhonglin Lin ◽  
Qi Xie ◽  
Yan Zhang
Keyword(s):  
Radiation Thermometry ◽  
Hydroxyl Group ◽  
Interference Signal ◽  
Engine Vibration ◽  
Combustion Technology ◽  
Lean Fuel ◽  
Combustion Oscillation ◽  
Aero Engines ◽  
Temperature Measurement System ◽  
Multispectral Radiation Thermometry

After the lean fuel premixed combustion technology is applied to aero engines, severe combustion oscillations will be cased and led to hidden safety hazards such as engine vibration, further energy waste and other problems. Therefore, it is increasingly important to actively control combustion oscillations. In this paper, a multispectral radiation thermometry (MRT) is used to analyze the hydroxyl group, which is a measurable research object in the combustion chamber of an aero engine, and to fit the functional relationship between the radiation intensity ratio and the temperature in different bands. The theoretical value of the error is <2%. At the same time, in order to solve the problem of weak detection signal and excessive interference signal, an improved frequency domain filtering method based on fast Fourier transform is designed. Besides, the FPGA platform is used to ensure the real-time performance of the temperature measurement system, and simulations and experiments are performed. An oscillating signal with an oscillation frequency of 315 Hz is obtained on the established test platform, and the error is only 1.42%.

scholarly journals Investigation of High-Temperature Normal Infrared Spectral Emissivity of ZrO2 Thermal Barrier Coating Artefacts by the Modified Integrated Blackbody Method

Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 235
Author(s):  
Tong Zhang ◽  
Xuyao Song ◽  
Gongjin Qi ◽  
Baolin An ◽  
Wei Dong ◽  
...  
Keyword(s):  
High Temperature ◽  
Thermal Barrier Coating ◽  
Radiation Thermometry ◽  
Spectral Emissivity ◽  
Standard Uncertainty ◽  
Thermal Barrier ◽  
Normal Spectral Emissivity ◽  
Zro2 Coating ◽  
Barrier Coating ◽  
Relative Standard

Zirconium oxide (ZrO2) is widely used as the thermal barrier coating in turbines and engines. Accurate emissivity measurement of ZrO2 coating at high temperatures, especially above 1000 °C, plays a vital role in thermal modelling and radiation thermometry. However, it is an extremely challenging enterprise, and very few high temperature emissivity results with rigorously estimated uncertainties have been published to date. The key issue for accurately measuring the high temperature emissivity is maintaining a hot surface without reflection from the hot environment, and avoiding passive or active oxidation of material, which will modify the emissivity. In this paper, a novel modified integrated blackbody method is reported to measure the high temperature normal spectral emissivity of ZrO2 coating in the temperature range 1000 °C to 1200 °C and spectral range 8 μm to 14 μm. The results and the associated uncertainty of the measurement were estimated and a relative standard uncertainty better than 7% (k = 2) is achieved.

On-Line Temperature Measurement Inside a Thermal Barrier Sensor Coating During Engine Operation

2014 ◽  
Author(s):  
A. Yañez Gonzalez ◽  
C. C. Pilgrim ◽  
J. P. Feist ◽  
P. Y. Sollazzo ◽  
F. Beyrau ◽  
...  
Keyword(s):  
Substrate Temperature ◽  
Temperature Measurement ◽  
Measurement System ◽  
Bond Coat ◽  
Operating Conditions ◽  
Thermal Barrier ◽  
Temperature Phase ◽  
Engine Operation ◽  
On Line ◽  
Line Temperature

Existing thermal barrier coatings (TBC) can be adapted enhancing their functionalities such that they not only protect critical components from hot gases, but also can sense their own material temperature or other physical properties. The self-sensing capability is introduced by embedding optically active rare earth ions into the thermal barrier ceramic. When illuminated by light the material starts to phosphoresce and the phosphorescence can provide in-situ information on temperature, phase changes, corrosion or erosion of the coating subject to the coating design. The integration of an on-line temperature detection system enables the full potential of TBCs to be realised due to improved accuracy in temperature measurement and early warning of degradation. This in turn will increase fuel efficiency and will reduce CO2 emissions. This paper reviews the previous implementation of such a measurement system into a Rolls-Royce jet engine using dysprosium doped yttrium-stabilised-zirconia as a single layer and a dual layer sensor coating material. The temperature measurements were carried out on cooled and uncooled components on a combustion chamber liner and on nozzle guide vanes respectively. The paper investigates the interpretation of those results looking at coating thickness effects and temperature gradients across the TBC. For the study a specialised cyclic thermal gradient burner test rig was operated and instrumented using equivalent instrumentation to that used for the engine test. This unique rig enables the controlled heating of the coatings at different temperature regimes. A long-wavelength pyrometer was employed detecting the surface temperature of the coating in combination with the phosphorescence detector. A correction was applied to compensate for changes in emissivity using two methods. A thermocouple was used continuously measuring the substrate temperature of the sample. Typical gradients across the coating are less than 1K/μm. As the excitation laser penetrates the coating it generates phosphorescence from several locations throughout the coating and hence provides an integrated signal. The study successfully proved that the temperature indication from the phosphorescence coating remains between the surface and substrate temperature for all operating conditions. This demonstrates the possibility to measure inside the coating closer to the bond coat. The knowledge of the bond coat temperature is relevant to the growth of the thermally grown oxide which is linked to the delamination of the coating and hence determines its life. Further, the data is related to a one dimensional phosphorescence model determining the penetration depth of the laser and the emission. Note: a video of the measurement system can be watched under: [http://www.youtube.com/watch?v=T6uXN1__Z7I].

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