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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2007

Single-Shot Rotational Raman Thermometry for Turbulent Flames Using a Low-Resolution Bandwidth Technique

An alternative optical thermometry technique that utilizes the low-resolution (order 10(exp 1)/cm) pure-rotational spontaneous Raman scattering of air is developed to aid single-shot multiscalar measurements in turbulent combustion studies. Temperature measurements are realized by correlating the measured envelope bandwidth of the pure-rotational manifold of the N2/O2 spectrum with a theoretical prediction of a species-weighted bandwidth. By coupling this thermometry technique with conventional vibrational Raman scattering for species determination, we demonstrate quantitative spatially resolved, single-shot measurements of the temperature and fuel/oxidizer concentrations in a high-pressure turbulent Cf4-air flame. Our technique provides not only an effective means of validating other temperature measurement methods, but also serves as a secondary thermometry technique in cases where the anti-Stokes vibrational N2 Raman signals are too low for a conventional vibrational temperature analysis.

Kojima, Jun↗
NASA NTRS2015

Understanding Radiation Thermometry

This document is a two-part course on the theory and practice of radiation thermometry. Radiation thermometry is the technique for determining the temperature of a surface or a volume by measuring the electromagnetic radiation it emits. This course covers the theory and practice of radiative thermometry and emphasizes the modern application of the field using commercially available electronic detectors and optical components. The course covers the historical development of the field, the fundamental physics of radiative surfaces, along with modern measurement methods and equipment.

Risch Timothy K.↗
NASA NTRS2015

Understanding Radiation Thermometry

This document is a two-part course on the theory and practice of radiation thermometry. Radiation thermometry is the technique for determining the temperature of a surface or a volume by measuring the electromagnetic radiation it emits. This course covers the theory and practice of radiative thermometry and emphasizes the modern application of the field using commercially available electronic detectors and optical components. The course covers the historical development of the field, the fundamental physics of radiative surfaces, along with modern measurement methods and equipment.

Risch, Timothy K.↗
NASA NTRS2020

Nitric Oxide Laser-Induced Fluorescence Rotational Thermometry in a Hypersonic Non-Equilibrium Flow

Spatially-resolved nitric oxide (NO) planar laser-induced fluorescence (PLIF) rotational thermometry was performed on a Mach 5 non-equilibrium flow around a blunt-body specimen in the Hypersonic Materials Environmental Test System (HyMETS) arc-heat wind tunnel at the NASA Langley Research Center. Transitions within the (0,0) band in the A(exp⁡ 2)∑(sup⁡ +) - X(exp⁡ 2)Π system of NO were excited with a 10 Hz pulsed ultra-violet laser. A multi-line fitting algorithm was applied to the PLIF spectra and transitions were filtered based on an iterative method that maximizes thermometry accuracy. NO PLIF thermometry results are compared to non-equilibrium computational fluid dynamics (CFD) simulations reported in the literature. Differences between the experiment and CFD are quantified for the free-stream, post-shock, shear-layer, and expansion-fan regions of the flow. Potential sources of error, applicable to both the CFD and experiment, are discussed.

Connor C McDougall↗
NASA NTRS2016

Temperature Mapping of Air Film-Cooled Thermal Barrier Coated Surfaces Using Phosphor Thermometry

While the effects of thermal barrier coating (TBC) thermal protection and air film cooling effectiveness for jet engine components are usually studied separately, their contributions to combined cooling effectiveness are interdependent and are not simply additive. Therefore, combined cooling effectiveness must be measured to achieve an optimum balance between TBC thermal protection and air film cooling. Phosphor thermometry offers several advantages for mapping temperatures of air film cooled surfaces. While infrared thermography has been typically applied to study air film cooling effectiveness, temperature accuracy depends on knowing surface emissivity (which may change) and correcting for effects of reflected radiation. Because decay time-based full-field phosphor thermometry is relatively immune to these effects, it can be applied advantageously to temperature mapping of air film-cooled TBC-coated surfaces. In this presentation, an overview will be given of efforts at NASA Glenn Research Center to perform temperature mapping of air film-cooled TBC-coated surfaces in a burner rig test environment. The effects of thermal background radiation and flame chemiluminescence on the measurements are investigated, and the strengths and limitations of this method for studying air film cooling effectiveness are discussed.

air film cooling↗
NASA NTRSDate not supplied

10-kHz PLIF Thermometry for a Turbulent Jet Flame using Single Burst-mode OPO

Two-color Planar laser-induced fluorescence (TC-PLIF) thermometry techniques that employ two laser systems and two cameras face challenges when implemented in practical combustion facilities because of experimental complexity and multiple laser and camera requirements, particularly for high-speed TC-PLIF. To circumvent those problems, we developed a fast, dual-wavelength switching, burst-mode OPO technology to significantly reduce the experimental complexity of high-speed TC-PLIF thermometry and simplify its implementation in harsh combustion and flow test facilities. A fast, dual-wavelength switched seed laser enabled a high-energy, high-repetition-rate burst-mode laser to generate two 10-kHz pulse trains at wavelengths of ~354.8 nm. The injection-seeded OPO efficiently converts the burst-mode laser output to285.62 nm and 285.67 nm to excite the Q2(12) and P1(8) OH transitions. PLIF images were collected from each of the two excitation transitions with a single camera and an UV intensifier, and intensity ratios from the images were used to determine local temperatures. Ten kHz hydroxyl radical (OH) TC-PLIF for premixedCH4/Air/H2 jet flame was demonstrated.

thermometry↗
NASA NTRSDate not supplied

10-kHz PLIF Thermometry for Turbulent Jet Flame using Single Burst-mode OPO

Two-color Planar Laser-Induced Fluorescence (TC-PLIF) thermometry techniques that employ two laser systems and two cameras face challenges when implemented in practical combustion facilities because of experimental complexity and multiple laser and camera requirements, particularly for high-speed TC-PLIF. To circumvent those problems, we developed a fast, dual-wavelength switching, burst-mode OPO technology to significantly reduce the experimental complexity of high-speed TC-PLIF thermometry and simplify its implementation in harsh combustion and flow test facilities. A fast, dual-wavelength switched seed laser enabled a high-energy, high-repetition-rate burst-mode laser to generate two 10-kHz pulse trains at wavelengths of ~354.8 nm. The injection-seeded OPO efficiently converts the burst-mode laser output to 285.62 nm and 285.67 nm to excite the Q2(12) andP1(8) OH transitions. PLIF images were collected from each of the two excitation transitions with a single camera and an UV intensifier, and intensity ratios from the images were used to determine local temperatures. Ten kHz hydroxyl radical (OH) TC-PLIF for premixedCH4/Air/H2 jet flame was demonstrated.

thermometry↗
NASA NTRS2012

Measurement of Two-Phase Flow and Heat Transfer Parameters using Infrared Thermometry

A novel technique to measure heat transfer and liquid film thickness distributions over relatively large areas for two-phase flow and heat transfer phenomena using infrared (IR)thermometry is described. IR thermometry is an established technology that can be used to measure temperatures when optical access to the surface is available in the wavelengths of interest. In this work, a midwave IR camera (3.6-5.1 microns) is used to determine the temperature distribution within a multilayer consisting of a silicon substrate coated with a thin insulator. Since silicon is largely transparent to IR radiation, the temperature of the inner and outer walls of the multilayer can be measured by coating selected areas with a thin, IR opaque film. If the fluid used is also partially transparent to IR, the flow can be visualized and the liquid film thickness can be measured. The theoretical basis for the technique is given along with a description of the test apparatus and data reduction procedure. The technique is demonstrated by determining the heat transfer coefficient distributions produced by droplet evaporation and flow boiling heat transfer.

Kim, Tae-Hoon↗
NASA NTRS2018

Temperature Mapping Above and Below Air Film-Cooled Thermal Barrier Coatings Using Phosphor Thermometry

Thermal barrier coatings (TBCs) are typically used in conjunction with air film cooling to maximize overall cooling effectiveness and reliability while minimizing sacrifices in engine performance. The effects of thermal barrier coating (TBC) thermal protection and air film cooling effectiveness have usually been studied separately; however, their contributions to combined cooling effectiveness are interdependent and are not simply additive. The combined cooling effectiveness is always less than the sum of the cooling effectiveness of stand-alone TBC protection and stand-alone air film cooling. These diminishing returns arise because adding the thermally insulating TBC between the cooling air and the surface to be cooled reduces the air film cooling effectiveness and because the air film cooling reduces the heat flux through the TBC and therefore reduces the temperature difference sustained across the TBC thickness. Due to these considerations, combined cooling effectiveness must be measured to achieve an optimum balance between TBC thermal protection and air film cooling. In this investigation, temperature mapping above and below air film-cooled TBCs was performed using luminescence lifetime imaging-based phosphor thermometry. Measurements were performed in the NASA GRC Mach 0.3 burner rig on a TBC-coated plate using a scaled-up cooling hole geometry where both the hot mainstream gas temperature and the blowing ratio were varied. Surface temperature maps were obtained from a Cr-doped GdAlO3 thermographic phosphor deposited on the surface of the electron-beam vapor-deposited yttria-stabilized zirconia (YSZ) TBC. From separate plates, temperature maps from the bottom of the TBC were obtained from a thin Er-doped YSZ layer integrated into the TBC below the overlying undoped YSZ. Procedures for temperature and cooling effectiveness mapping above and below the air film-cooled TBC surface are described. Most importantly, these measurements enable mapping the combined cooling effectiveness below the TBC, which is more important than surface cooling effectiveness when there is a barrier coating between the hot mainstream gas and the surface that needs thermal protection. Advantages of the luminescence lifetime imaging method over infrared thermography, as well as its limitations to steady-state conditions are discussed.

cooling effectiveness.↗
NASA NTRS1971

Noise thermometry with the Josephson effect

Noise thermometry by Josephson effect, demonstrating self excitation random frequency modulation with thermal noise and thermometer having microkelvin noise temperature measurement capability

Kamper, R. A.↗
NASA NTRS1972

Theory and measurement of emittance properties for radiation thermometry applications.

Some basic concepts of radiation physics are briefly reviewed to provide an introduction to the radiative properties - including emittance, reflectance, absorptance, and transmittance - their definitions, interrelations, theory and methods of measurement. Analyzed data showing typical characteristics of temperature and wavelength dependence, surface effects and environmental influences on the radiation properties of selected classes of materials are presented. Emphasis is placed on those emittance properties of particular interest to conventional radiation thermometry applications, but sufficient generality on all properties is presented to be useful for new or unusual techniques where a more detailed understanding of the behavior of materials is desirable. Data sources are identified to assist the reader in locating property information. It is the intention of the paper to give the reader a background to become more fully aware of the pitfalls, limitations, but of course, advantages in the use of data from the literature. The paper is written in the form of an abbreviated review fully documenting the more important topics and concepts which can only be treated briefly.

Dewitt, D. P.↗