0
Research Papers: Radiative Heat Transfer

Effective Spectral Emissivity of Gas Turbine Blades for Optical Pyrometry

[+] Author and Article Information
Jibin Tian

Key Laboratory for Thermal Science and
Power Engineering of Ministry of Education,
Beijing Key Laboratory of CO2 Utilization and
Reduction Technology,
Department of Thermal Engineering,
Tsinghua University,
Beijing 100084, China

Tairan Fu

Key Laboratory for Thermal Science and
Power Engineering of Ministry of Education,
Beijing Key Laboratory of CO2 Utilization and
Reduction Technology,
Department of Thermal Engineering,
Tsinghua University,
Beijing 100084, China
e-mail: trfu@mail.tsinghua.edu.cn

Qiaoqi Xu

National Research Center of Gas turbine and
IGCC Technology,
Department of Thermal Engineering,
Tsinghua University,
Beijing 100084, China

Hongde Jiang

National Research Center of Gas turbine and IGCC Technology,
Department of Thermal Engineering,
Tsinghua University,
Beijing 100084, China

1Corresponding author.

Contributed by the Heat Transfer Division of ASME for publication in the JOURNAL OF HEAT TRANSFER. Manuscript received October 1, 2016; final manuscript received December 23, 2016; published online March 15, 2017. Assoc. Editor: Laurent Pilon.

J. Heat Transfer 139(7), 072701 (Mar 15, 2017) (6 pages) Paper No: HT-16-1617; doi: 10.1115/1.4035732 History: Received October 01, 2016; Revised December 23, 2016

Turbine blade temperature measurements are important for monitoring the turbine engine performance to protect the hot components from damage due to excess temperatures. However, the reflected radiation from the blades and the surrounding environment complicate the blade temperature measurements by optical pyrometers. This study characterizes the effect of the reflected radiation on the effective spectral emissivity of a three-dimensional turbine blade in a confined turbine space for optical pyrometry temperature measurements. The effective spectral emissivity distribution on a three-dimensional blade was numerically determined for various wavelengths (0.8–15.0 μm) and actual blade surface emissivities for a specified turbine blade model. When the actual spectral emissivity of the blade surface is assumed to be 0.5, the effective spectral emissivity varies from 0.5 to 0.538 at the longer wavelength of 10.0 μm and further increases from 0.5 to 1.396 at the shorter wavelength of 0.9 μm. The results show that the effective emissivity distributions at shorter wavelengths differ greatly from those at longer wavelengths. There are also obvious differences between the effective spectral emissivity and the actual surface emissivity at shorter wavelengths. The effect of the effective emissivity on the temperature measurement accuracy, when using the optical pyrometry, was also investigated for various wavelengths (0.8–15.0 μm). The results show that the radiation reflected from the blades has less effect on the temperature measurements than on the effective emissivity, especially at the shorter wavelengths of 0.8–3.0 μm. However, the temperature measurements still need to be corrected using the effective spectral emissivity to improve the temperature calculation accuracy. This analysis provides guidelines for choosing the optimum measurement wavelengths for optical pyrometry in turbine engines.

FIGURES IN THIS ARTICLE
<>
Copyright © 2017 by ASME
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Fig. 1

Simplified model of the rotor blades and stator vanes

Grahic Jump Location
Fig. 2

Temperature distribution on the turbine stator vane with temperatures of 449–1052 °C

Grahic Jump Location
Fig. 3

Temperature distribution on the turbine rotor blade with temperatures of 602–1206 °C

Grahic Jump Location
Fig. 4

Sketch of the radiation temperature measurement of blade #4 by an optical pyrometer

Grahic Jump Location
Fig. 5

View factors between two triangular elements

Grahic Jump Location
Fig. 6

Effective spectral emissivity distribution at 10.0 μm (blade #4)

Grahic Jump Location
Fig. 7

Effective spectral emissivity distribution at 0.9 μm (blade #4)

Grahic Jump Location
Fig. 8

Maximum relative emissivity error for wavelengths of 0.8–15 μm (rotor blade #4)

Grahic Jump Location
Fig. 9

Temperature errors without the reflected radiation correction for wavelengths of 0.8–15.0 μm

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In