Temperature-Dependent Emissivity Models of Aeronautical Alloy DD6 and Modified Function for Emissivity Computation with
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Temperature‑Dependent Emissivity Models of Aeronautical Alloy DD6 and Modified Function for Emissivity Computation with Different Roughness Yanfen Xu1 · Kaihua Zhang1 · Kun Yu1 · Yanlei Liu1 · Yufang Liu1 Received: 18 August 2020 / Accepted: 10 October 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract In this study, the spectral emissivity of aeronautical alloy DD6 at eight temperatures (473 K, 523 K, 573 K, 623 K, 673 K, 723 K, 773 K and 823 K) over the spectral range from 3 μm to 20 μm is systematically studied under argon condition. The multi-temperature calibration method is adopted to accurately obtain the FTIR spectrometer response, and then the improved method that eliminates the disturbances caused by background radiation is used for spectral emissivity determination. The effects of temperature, wavelength and surface roughness on the spectral emissivity of DD6 are investigated. The results show that the spectral emissivity increases with increasing temperature and decreases with increasing wavelength, and the emissivity increases with increasing surface roughness. The fitting relationship between the spectral emissivity and temperature is established, and it is found that the fitting results of the complex model are more consistent than those of other models. To verify the validity of the complex model, the temperature inferred from the model is compared with that measured by the radiometer and thermocouple directly. The modified emissivity model based on the Agababov roughness function is established to infer the spectral emissivity of samples with different surface roughness. The relative combined uncertainty of spectral emissivity is evaluated to be better than 3.2% except for the atmospheric absorption bands. Keywords Fitting model · Ni-based alloy DD6 · Spectral emissivity · Surface roughness
* Kaihua Zhang [email protected] * Yufang Liu yf‑[email protected] 1
Henan Key Laboratory of Infrared Materials & Spectrum Measures and Applications, School of Physics, Henan Normal University, Xinxiang 453007, Henan, People’s Republic of China
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International Journal of Thermophysics
(2021) 42:7
1 Introduction Ni-based alloys are the preferred material for turbine blades due to their properties of oxidation resistance, refractory and corrosion resistance [1]. Turbine blades are an important part of the aero-engine and work in a high-temperature environment. Accurate measurement of the blade temperature is crucial in order to improve the working efficiency of an aero-engine. The contact temperature measurement method is not suitable due to its short lifetime in a high-temperature environment. The radiation thermometry is an optimum approach because of the advantages to be contamination-free, convenient, non-destructive and non-contact [2–4]. However, it is essential to know the spectral emissivity of the object in radiation measurements [5]. Furthermore, the metal spectral emissivity is affected by a great number of factors
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