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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 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1983

Dynamic gas temperature measurement system

A gas temperature measurement system with compensated frequency response of 1 KHz and capability to operate in the exhaust of a gas turbine combustor was developed. Environmental guidelines for this measurement are presented, followed by a preliminary design of the selected measurement method. Transient thermal conduction effects were identified as important; a preliminary finite-element conduction model quantified the errors expected by neglecting conduction. A compensation method was developed to account for effects of conduction and convection. This method was verified in analog electrical simulations, and used to compensate dynamic temperature data from a laboratory combustor and a gas turbine engine. Detailed data compensations are presented. Analysis of error sources in the method were done to derive confidence levels for the compensated data.

Elmore, D. L.↗
NASA NTRS2001

Validation of Temperature Measurements from the Airborne Raman Ozone Temperature and Aerosol Lidar During SOLVE

The Airborne Raman Ozone, Temperature and Aerosol Lidar (AROTEL) participated in the recent Sage III Ozone Loss and Validation Experiment (SOLVE) by providing profiles of aerosols, polar stratospheric clouds (PSCs), ozone and temperature with high vertical and horizontal resolution. Temperatures were derived from just above the aircraft to approximately 60 kilometers geometric altitude with a reported vertical resolution of between 0.5 and 1.5 km. The horizontal footprint varied from 4 to 70 km. This paper explores the measurement uncertainties associated with the temperature retrievals and makes comparisons with independent, coincident, measurements of temperature. Measurement uncertainties range from 0.1 K to approximately 4 K depending on altitude and integration time. Comparisons between AROTEL and balloon sonde temperatures retrieved under clear sky conditions using both Rayleigh and Raman scattered data showed AROTEL approximately 1 K colder than sonde values. Comparisons between AROTEL and the Meteorological Measurement System (MMS) on NASA's ER-2 show AROTEL being from 2-3 K colder for altitudes ranging from 14 to 18 km. Temperature comparisons between AROTEL and the United Kingdom Meteorological Office's model showed differences of approximately 1 K below approximately 25 km and a very strong cold bias of approximately 12 K at altitudes between 30 and 35 km.

Burris, John↗
NASA NTRS2003

Depth-Penetrating Temperature Measurements of Thermal Barrier Coatings Incorporating Thermographic Phosphors

Thermographic phosphors have been previously demonstrated to provide effective non-contact, emissivity-independent surface temperature measurements. Because of the translucent nature of thermal barrier coatings (TBCs), thermographic phosphor-based temperature measurements can be extended beyond the surface to provide depth-selective temperature measurements by incorporating the thermographic phosphor layer at the depth where the temperature measurement is desired. In this paper, thermographic phosphor (Y2O3:Eu) fluorescence decay time measurements are demonstrated to provide through-the-coating thickness temperature readings up to 1100 C with the phosphor layer residing beneath a 100 micron thick TBC (plasma-sprayed 8wt% yttria-stabilized zirconia). With an appropriately chosen excitation wavelength and detection configuration, it is shown that sufficient phosphor emission is generated to provide effective temperature measurements, despite the attenuation of both the excitation and emission intensities by the overlying TBC. This depth-penetrating temperature measurement capability should prove particularly useful for TBC diagnostics where a large thermal gradient is typically present across the TBC thickness. The fluorescence decay from the Y2O3:Eu layer exhibited both an initial short-term exponential rise and a longer-term exponential decay. The rise time constant was demonstrated to provide better temperature indication below 500 C while the decay time constant was a better indicator at higher temperatures.

Eldridge, Jeffrey I.↗
NASA NTRS1975

Error in temperature measurements due to conduction along the sensors

When a sensor is embedded in a solid body to measure its internal temperature, any conduction to or from its sensing element may cause the indicated temperature to be different from the true temperature. This paper describes an analysis of the error caused by conduction when there is an arbitrary temperature distribution in the body along the sensor. The sensor is modeled as a cylindrical fin and the appropriate conduction equation is solved. The solution gives a correction for the error which depends on such parameters as, depth of immersion, thermocouple wire and insulation properties, contact between the sensor and the body, and temperature distribution in the body. The latter may not be known, but the measured temperature distribution can be used as a first approximation. The corrected value can then be used to obtain a better estimate of the error. The results show good agreement with experimental observations.

Singh, B. S.↗
NASA NTRS1989

Proceedings of the Second Noncontact Temperature Measurement Workshop

The state of the art in noncontact temperature measurement (NCTM) technology was reviewed and the NCTM requirements of microgravity materials processing community identified. The workshop included technical presentations and discussions which ranged from research on advanced concepts for temperature measurement to laboratory research and development regarding measurement principles and state-of-the-art engineering practices for NCTM methodology in commercial and industrial applications. Technical presentations were made concerning: NCTM needs as perceived by several NASA centers, recent ground-based NCT, research and development of industry, NASA, academia, and selected national laboratories, work-in-progress communication, and technical issues of the implementation of temperature measurement in the space environment to facilitate future U.S. materials science investigations.

Hale, Robert R.↗
NASA NTRS1981

A comparison of laboratory measured temperatures with predictions for a spar/skin type aircraft structure

A typical spar/skin aircraft structure was heated nonuniformly in a laboratory and the resulting temperatures were measured. The heat transfer NASTRAN computer program was used to provide predictions. Calculated temperatures based on a thermal model with conduction, radiation, and convection features compared closely to measured spar temperatures. Results were obtained without the thermal conductivity, specific heat, or emissivity with temperature. All modes of heat transfer (conduction, radiation, and convection) show to affect the magnitude and distribution of structural temperatures.

Jenkins, J. M.↗
NASA NTRS1993

Dynamic gas temperature measurements using a personal computer for data acquisition and reduction

This report describes a dynamic gas temperature measurement system. It has frequency response to 1000 Hz, and can be used to measure temperatures in hot, high pressure, high velocity flows. A personal computer is used for collecting and processing data, which results in a much shorter wait for results than previously. The data collection process and the user interface are described in detail. The changes made in transporting the software from a mainframe to a personal computer are described in appendices, as is the overall theory of operation.

Fralick, Gustave C.↗
NASA NTRS1979

Temperature Measurement

The design, installation, checkout, calibration, and operation of a temperature measuring system to be used during tests of a liquid monopropellant rocket engine are discussed. Appendixes include: (1) temperature measurement system elemental uncertainties, and (2) tables and equations for use with thermocouples and resistance thermometers. Design guidelines are given for the critical components of each portion of the system to provide an optimum temperature measurement system which meets the performance criteria specified.

Source record↗
NASA NTRS1988

Temperature measurements in hypersonic air flows using laser-induced O2 fluorescence

An investigation is reported of the use of laser-induced fluorescence on oxygen for the measurement of air temperature and its fluctuations owing to turbulence in hypersonic wind tunnel flows. The results show that for temperatures higher than 60 K and densities higher than 0.01 amagat, the uncertainty in the temperature measurement can be less than 2 percent if it is limited by photon-statistical noise. The measurement is unaffected by collisional quenching and, if the laser fluence is kept below 1.5 J/sq cm, it is also unaffected by nonlinear effects which are associated with depletion of the absorbing states.

Laufer, Gabriel↗
NASA NTRS1998

Lidar temperature measurements at NY-Alesund (79N) during winter, 1998

During January and February, 1998, a measurements campaign was held at the Network for the Detection of Stratospheric Change (NDSC) Arctic site at Ny-Alesund (78.9N). Lidar measurements of ozone, temperature and aerosol parameters were made along with balloon sonde and microwave measurements of ozone. Atmospheric temperatures were measured between 10 and 70 km. During the time of the campaign an strong warming occurred at the stratopause, elevating the measured temperature by as much as 80 K. The height of the stratopause descended at this time to below 40 km.

McGee, T. J.↗
NASA NTRS2003

Midinfrared Temperature Measurement Technique Developed

Infrared thermography is the measuring of the temperature of an object by examining the spectral quantities of light emission. The microgravity combustion experiment Solid Inflammability Boundary at Low-Speeds (SIBAL) calls for full-field temperature measurements of a thin sheet of cellulosic fuel as a flame front moves across the fuel, and infrared thermography is the only technique that can accomplish this task. The thermography is accomplished by imaging the fuel with a midinfrared camera that is sensitive in the 3.0- to 5.0-microns wavelength region in conjunction with a 3.7 - to 4.1-microns bandpass filter to eliminate unwanted infrared radiation from components other than the fuel.

Santosuosso, George R.↗
NASA NTRS2011

Real-Time Thermographic-Phosphor-Based Temperature Measurements of Thermal Barrier Coating Surfaces Subjected to a High-Velocity Combustor Burner Environment

Surface temperature measurements were conducted on metallic specimens coated with an yttria-stabilized zirconia (YSZ) thermal barrier coating (TBC) with a YAG:Dy phosphor layer that were subjected to an aggressive high-velocity combustor burner environment. Luminescence-based surface temperature measurements of the same TBC system have previously been demonstrated for specimens subjected to static furnace or laser heating. Surface temperatures were determined from the decay time of the luminescence signal of the YAG:Dy phosphor layer that was excited by a pulsed laser source. However, the furnace and laser heating provides a much more benign environment than that which exists in a turbine engine, where there are additional challenges of a highly radiant background and high velocity gases. As the next step in validating the suitability of luminescence-based temperature measurements for turbine engine environments, new testing was performed where heating was provided by a high-velocity combustor burner rig at Williams International. Real-time surface temperature measurements during burner rig heating were obtained from the decay of the luminescence from the YAG:Dy surface layer. The robustness of several temperature probe designs in the sonic velocity, high radiance flame environment was evaluated. In addition, analysis was performed to show whether the luminescence decay could be satisfactorily extracted from the high radiance background.

Eldridge, Jeffrey I.↗
NASA NTRS1975

L-band, 1.2 m parabolic antenna-noise temperature measurement

Extensive antenna-noise temperature measurements at 1.6 GHz (L-band) were made using a 1.2 m (4 ft. diameter) parabolic dish antenna mounted on the flying bridge of a modern 15,690-ton, commercial-container ship. Both in-harbor and at-sea radiometer measurements were made that indicated a steady background, antenna-noise temperature value slightly less than 70 degrees Kelvin (K) at elevation angles of 5 percent, and greater, at 1.6 GHz. A comparison of theoretical and measured values indicate excellent agreement within about 5K for at-sea data. These measurements are helpful to RF equipment designers of maritime, L-band shipboard terminals for operation with the two, geostationary, maritime satellites, Marisat-A and -B.

Taylor, R. E.↗
NASA NTRS2013

Contact Thermocouple Methodology and Evaluation for Temperature Measurement in the Laboratory

Laboratory testing of advanced aerospace components very often requires highly accurate temperature measurement and control devices, as well as methods to precisely analyze and predict the performance of such components. Analysis of test articles depends on accurate measurements of temperature across the specimen. Where possible, this task is accomplished using many thermocouples welded directly to the test specimen, which can produce results with great precision. However, it is known that thermocouple spot welds can initiate deleterious cracks in some materials, prohibiting the use of welded thermocouples. Such is the case for the nickel-based superalloy MarM-247, which is used in the high temperature, high pressure heater heads for the Advanced Stirling Converter component of the Advanced Stirling Radioisotope Generator space power system. To overcome this limitation, a method was developed that uses small diameter contact thermocouples to measure the temperature of heater head test articles with the same level of accuracy as welded thermocouples. This paper includes a brief introduction and a background describing the circumstances that compelled the development of the contact thermocouple measurement method. Next, the paper describes studies performed on contact thermocouple readings to determine the accuracy of results. It continues on to describe in detail the developed measurement method and the evaluation of results produced. A further study that evaluates the performance of different measurement output devices is also described. Finally, a brief conclusion and summary of results is provided.

thermocouple↗