A Method of Measuring the Temperature Profile of a Thermal Barrier Coating Using Inverse Radiative Heat Transfer Methods

2011 ◽  
Author(s):  
Travis J. Moore ◽  
Matthew R. Jones
Keyword(s):  
Heat Transfer ◽  
Measurement Error ◽  
Absorption Coefficient ◽  
Temperature Profile ◽  
Radiative Heat ◽  
Thermal Barrier ◽  
Spectral Absorption ◽  
Spectral Absorption Coefficient ◽  
Barrier Coating ◽  
Spectral Emittance

Ceramic thermal barrier coatings (TBCs) are used in power generation and aerospace turbines to protect superalloy components from large and extended heat loads. These coatings allow for increased inlet temperatures, thereby increasing efficiency and reducing air cooling requirements. Knowledge of the temperature profile in a thermal barrier coating is critical for evaluating the TBC performance and monitoring its health, as well as for accurate simulation and modeling. Non-contact, non-destructive techniques for finding these temperature profiles are highly desirable. Current techniques are limited in that they cannot measure the entire temperature profile of the TBC along with its radiative properties. An inverse radiative heat transfer method capable of determining the temperature profile, as well as the spectral absorption coefficient and spectral emittance at various wavenumbers, of a TBC using non-contact techniques was developed. A model of the measurements of the intensity exiting the TBC, which account for the emission from the substrate as well as the emission and absorption of the TBC itself, was developed. The TBC was approximated as a one-dimensional, plane-parallel, non-scattering medium. Optimization methods were used to determine the desired parameters by minimizing the error between actual intensity measurements and those calculated from the model. This method was tested for a number of simulated measurements with and without measurement error. Even with 10% measurement error introduced, the base temperature of the TBC was determined with only 0.45% error while the error in the TBC surface temperature measurement was 3.36% and that in the spectral emittance of the bondcoat was 12%. The error in the spectral absorption coefficient was significant.

scholarly journals Spectral Absorption Coefficient of Additive Manufacturing Materials

2021 ◽  
Vol 13 (4) ◽  
Author(s):  
Nicholas J. Wallace ◽  
Matthew R. Jones ◽  
Nathan B. Crane
Keyword(s):  
Additive Manufacturing ◽  
Absorption Coefficient ◽  
Radiative Heat ◽  
Manufacturing Processes ◽  
Spectral Absorption ◽  
Spectral Absorption Coefficient ◽  
Polyamide 12 ◽  
Active Thermography ◽  
Uncertainty Estimates ◽  
Properties Of Materials

Abstract Active thermography techniques are of interest for quality assurance of additive manufacturing processes. However, accurate measurements of thermophysical properties of materials are required to successfully implement active thermography. In particular, the spectral absorption coefficient of materials commonly used in additive manufacturing must be known to accurately predict the spatial distribution of thermal energy generated from absorption of power emitted by a laser or pulsed flash lamp. Accurate measurements of these optical properties are also needed to develop greater understanding of additive manufacturing processes that rely on radiative heat transfer to fuse powders. This paper presents spectral absorption coefficient measurements and uncertainty estimates of fully and partially dense ABS, PLA, and Polyamide 12 samples.

Multi-Dimensional Radiative Transfer in Nongray Gases—General Formulation and the Bulk Radiative Exchange Approximation

1978 ◽  
Vol 100 (3) ◽  
pp. 486-491 ◽  
Author(s):  
S. S. Tsai ◽  
S. H. Chan
Keyword(s):  
Heat Flux ◽  
Radiative Transfer ◽  
Absorption Coefficient ◽  
Radiative Heat ◽  
Spectral Absorption ◽  
Spectral Absorption Coefficient ◽  
Multidimensional Problems ◽  
All Optical ◽  
Exchange Approximation ◽  
Radiative Exchange

The present paper presents a general formulation of the radiative heat flux and its divergence for multi-dimensional radiative problems involving nongray absorbing-emitting gases. The expressions obtained are in terms of total band absorptance rather than the spectral absorption coefficient. Thus the frequency integration is eliminated, and the expressions are more compact. They avoid the necessity of detailed spectral absorption coefficient data for radiative transfer computations. Also presented is the bulk radiative exchange approximation together with its refinement. It is proposed to circumvent the mathematical complexity inherently imbedded in nongray multidimensional problems. The approximation, which is valid in the optically thin and thick limits, is found to be general and useful, not only because of its simplicity, but also because of its accuracy in all optical conditions.

scholarly journals Conjugate Heat Transfer Characteristics in a Highly Thermally Loaded Film Cooling Configuration with TBC in Syngas

Aerospace ◽  
2019 ◽  
Vol 6 (2) ◽  
pp. 16
Author(s):  
Jing Ren ◽  
Xueying Li ◽  
Hongde Jiang
Keyword(s):  
Heat Transfer ◽  
Radiative Heat Transfer ◽  
Film Cooling ◽  
Conjugate Heat Transfer ◽  
Radiative Heat ◽  
Radiation Heat Transfer ◽  
Transfer Model ◽  
Plate Temperature ◽  
Total Percentage ◽  
Barrier Coating

Future power equipment tends to take hydrogen or middle/low heat-value syngas as fuel for low emission. The heat transfer of a film-cooled turbine blade shall be influenced more by radiation. Its characteristic of conjugate heat transfer is studied experimentally and numerically in the paper by considering radiation heat transfer, multicomposition gas, and thermal barrier coating (TBC). The Weighted Sum of Gray Gases Spectral Model and the Discrete Transfer Model are utilized to solve the radiative heat transfer in the multicomposition field, while validated against the experimental data for the studied cases. It is shown that the plate temperature increases significantly when considering the radiation and the temperature gradient of the film-cooled plate becomes less significant. It is also shown that increasing percentage of steam in gas composition results in increased temperature on the film-cooled plate. The normalized temperature of the film-cooled plate decreases about 0.02, as the total percentage of steam in hot gas increases 7%. As for the TBC effect, it can smooth out the temperature distribution and insulate the heat to a greater extent when the radiative heat transfer becomes significant.

Preliminary Testing of Metal-Based Thermal Barrier Coating in a Spark-Ignition Engine

2009 ◽  
Author(s):  
Michael Marr ◽  
James S. Wallace ◽  
Larry Pershin ◽  
Sanjeev Chandra ◽  
Javad Mostaghimi
Keyword(s):  
Heat Transfer ◽  
Thermal Barrier Coating ◽  
Substrate Surface ◽  
Temperature Fluctuations ◽  
Spark Ignition ◽  
Spark Ignition Engine ◽  
Thermal Barrier ◽  
Cylinder Wall ◽  
Test Results ◽  
Barrier Coating

A novel metal-based thermal barrier coating was tested in a spark-ignition engine. The coating was applied to the surface of aluminum plugs and exposed to in-cylinder conditions through ports in the cylinder wall. Temperatures were measured directly behind the coating and within the plug 3 and 11 mm from the surface. In-cylinder pressures were measured and analyzed to identify and quantify knock. Test results suggest the coating does not significantly reduce overall heat transfer, but it does reduce the magnitude of temperature fluctuations at the substrate surface. It was found that heat transfer can be reduced by reducing the surface roughness of the coating. The presence of the coating did not promote knock.

scholarly journals Investigation of Cooling Performances of a Non-Film-Cooled Turbine Vane Coated with a Thermal Barrier Coating Using Conjugate Heat Transfer

Energies ◽  
2018 ◽  
Vol 11 (4) ◽  
pp. 1000 ◽  
Author(s):  
Prasert Prapamonthon ◽  
Soemsak Yooyen ◽  
Suwin Sleesongsom ◽  
Daniele Dipasquale ◽  
Huazhao Xu ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Barrier Coating ◽  
Conjugate Heat Transfer ◽  
Thermal Barrier ◽  
Barrier Coating ◽  
Turbine Vane
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