Use of a multiwavelength pyrometer in several elevated temperature aerospace applications

Ng, Daniel; Fralick, Gustave C.

doi:10.1063/1.1340558

Cited by 95 publications

(32 citation statements)

References 8 publications

(4 reference statements)

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“…Considering the three conditions of particles that can exist in the spray stream -solid, partially molten and fully moltenthe radiated intensity as detected by the pyrometer is dependent on the optical properties of solid and liquid zirconia. In previously published research paper, Ng et al (40) have analyzed and presented results of the case of multi-wavelength pyrometry applied to optically transparent materials. They have demonstrated that when the principle is implemented by acquiring the spectrum over a large range of wavelengths, it is possible to distinguish the contribution from the surface and from the bulk of a transparent material.…”

Section: Variations In Particle Distributions Through the Complete Prmentioning

confidence: 98%

A Critical Assessment of Particle Temperature Distributions During Plasma Spraying: Experimental Results for YSZ

Streibl

Vaidya

Friis

et al. 2006

Plasma Chem Plasma Process

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Plasma sprayed coatings of Yttria Stabilized Zirconia (YSZ) have been studied extensively through the years to understand variations in coating properties as well as to achieve control on microstructure of the coatings. The requirement for microstructural control and reliability have become all the more important as coatings have now become part of an integrated "prime reliant" design strategy aimed at increasing turbine inlet temperature and associated efficiencies. One of the important thrusts in monitoring and controlling the process has been the application of process sensors that measure spray stream characteristics, notably particle temperature and velocity. Although single particle-based measurements have been available for some time, in general control strategies based on particle state rely on average values of temperature and velocity. In this study, a detailed examination of particle temperature distributions is presented. When systematically examined over a wide range of operating conditions of the resulting range of particle temperatures, a significant structure in the statistical distribution has been observed. A close inspection of the data indicates that this distribution can be interpreted as melting state indicator for YSZ. A characteristic peak at the melting point of ZrO 2 (error in absolute T -measurement is ≈ ±10%) can be used as an indicator for re-solidified particles. In the past, control strategies based on process diagnostic sensors have been based on average particle temperatures and velocities. Although the average values seem to be promising as control parameters, it has been shown through our results that different melting states could be demonstrated for the same average T and V settings. The melting state in turn has an important bearing on the coating structure and properties. It therefore implies that a process control strategy (to maintain coating quality) based on in flight particle sensors will have to take these findings into account. As an example, one strategy of process control would not only define the process in terms of the average particle temperature and velocity but also include the effect that parameter changes have on distributions.

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Section: Variations In Particle Distributions Through the Complete Prmentioning

confidence: 98%

A Critical Assessment of Particle Temperature Distributions During Plasma Spraying: Experimental Results for YSZ

Streibl

Vaidya

Friis

et al. 2006

Plasma Chem Plasma Process

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“…Previous studies were devoted either to emissivity determination of ceramic samples under isothermal conditions [11][12][13][14] or to accurate prediction of temperature distributions in ceramics [15,16]. The present research is a contribution to characterizations of non-isothermal TBCs for mean temperatures higher than 1000 • C. The main objective is to determine the infrared radiative emission of ceramic samples under realistic thermal boundary conditions that correspond to samples submitted to high heat flux on one side only.…”

Section: Introductionmentioning

confidence: 98%

Experimental and Theoretical Characterization of Emission from Ceramics at High Temperature: Investigation on Yttria-Stabilized Zirconia and Alumina

et al. 2010

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This study is a contribution to characterizations of non-isothermal ceramic samples, for mean temperatures higher than 1000 • C. The objective is to determine the infrared radiative emission, of materials often used as thermal barrier coatings, under realistic thermal boundary conditions. The problem is treated by both experimental and numerical approaches that reveal additional ways of investigation. Results from sintered zirconia and plasma-sprayed alumina are presented. The experimental bench, designed and built to perform emission measurements on semi-transparent ceramics at high temperature, is described. The numerical code used to solve coupled conduction-radiation heat transfers in semi-transparent media is introduced. Special attention is paid to calculation of radiative properties of plasma-sprayed samples characterized by their complex internal microstructure. Experimental and theoretical emission factors obtained from these kinds of ceramics samples are compared and analyzed. The influence of the inside temperature gradient on emission is discussed.

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“…In the study of radiation pyrometry theories and technologies, the complexity and uncertainty of actual object spectrum emissivity and the calibration problem caused by the temperature field measurement are always the key obstacles for accurate temperature measurement. Thus many radiation pyrometry methods and technologies arose [2][3][4][5][6][7][8][9][10][11][12][13] . However, our preliminary study put forward the primary spectrum pyrometry [14][15][16] based on the waveband measurement, the emissivity model in the narrow waveband and the normalization processing, and realized the true temperature field measurement without the calibrations of emissivity and spatial geometry.…”

mentioning

confidence: 99%

The application analyses for primary spectrum pyrometer

Cheng

Zhong

2007

Sci. China Ser. G-Phys. Mech. Astron.

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In the applications of primary spectrum pyrometry, based on the dynamic range and the minimum sensibility of the sensor, the application issues, such as the measurement range and the measurement partition, were investigated through theoretical analyses. For a developed primary spectrum pyrometer, the theoretical predictions of measurement range and the distributions of measurement partition were presented through numerical simulations. And the measurement experiments of high-temperature blackbody and standard temperature lamp were processed to further verify the above theoretical analyses and numerical results. Therefore the research in the paper provides the helpful supports for the applications of primary spectrum pyrometer and other radiation pyrometers.primary spectrum pyrometry, radiation temperature measurement, temperature, emissivity, measurement range, measurement partition The principle of primary spectrum pyrometryPlanck Law is the fundamental of radiation temperature measurements, which indicates the quantitative relationship between the radiation intensity and the temperature of ideal blackbody [1] . In the study of radiation pyrometry theories and technologies, the complexity and uncertainty of actual object spectrum emissivity and the calibration problem caused by the temperature field measurement are always the key obstacles for accurate temperature measurement. Thus many radiation pyrometry methods and technologies arose [2][3][4][5][6][7][8][9][10][11][12][13] . However, our preliminary study put forward the primary spectrum pyrometry [14][15][16] based on the waveband measurement, the emissivity model in the narrow waveband and the normalization processing, and realized the true temperature field measurement without the calibrations of emissivity and spatial geometry. In applications, primary spectrum pyrometry is only applicable for those objects with continuous radiation features and the

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Use of a multiwavelength pyrometer in several elevated temperature aerospace applications

Cited by 95 publications

References 8 publications

A Critical Assessment of Particle Temperature Distributions During Plasma Spraying: Experimental Results for YSZ

A Critical Assessment of Particle Temperature Distributions During Plasma Spraying: Experimental Results for YSZ

Experimental and Theoretical Characterization of Emission from Ceramics at High Temperature: Investigation on Yttria-Stabilized Zirconia and Alumina

The application analyses for primary spectrum pyrometer

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