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Results for “TEMPERATURE MEASUREMENT”

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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS1970

Simple, accurate temperature-measuring instrument

Compact instrument, composed of integrated circuits and a temperature-sensitive platinum resistor, measures temperature over a wide dynamic range. Ultimate accuracy is limited by nonlinearity of the platinum resistor. With proper calibration and current regulation to within 0.01 percent, a measurement accuracy of 0.05 percent can be achieved.

Mc Fadin, L. W.↗
NASA NTRS2015

Estimation of Surface Temperature and Heat Flux by Inverse Heat Transfer Methods Using Internal Temperatures Measured While Radiantly Heating a Carbon/Carbon Specimen up to 1920 F

The ability to solve the heat conduction equation is needed when designing materials to be used on vehicles exposed to extremely high temperatures; e.g. vehicles used for atmospheric entry or hypersonic flight. When using test and flight data, computational methods such as finite difference schemes may be used to solve for both the direct heat conduction problem, i.e., solving between internal temperature measurements, and the inverse heat conduction problem, i.e., using the direct solution to march forward in space to the surface of the material to estimate both surface temperature and heat flux. The completed research first discusses the methods used in developing a computational code to solve both the direct and inverse heat transfer problems using one dimensional, centered, implicit finite volume schemes and one dimensional, centered, explicit space marching techniques. The developed code assumed the boundary conditions to be specified time varying temperatures and also considered temperature dependent thermal properties. The completed research then discusses the results of analyzing temperature data measured while radiantly heating a carbon/carbon specimen up to 1920 F. The temperature was measured using thermocouple (TC) plugs (small carbon/carbon material specimens) with four embedded TC plugs inserted into the larger carbon/carbon specimen. The purpose of analyzing the test data was to estimate the surface heat flux and temperature values from the internal temperature measurements using direct and inverse heat transfer methods, thus aiding in the thermal and structural design and analysis of high temperature vehicles.

Pizzo, Michelle↗
NASA NTRS2022

Thermocouple Temperature Measurements in Selective Laser Melting Additive Manufacturing

The extreme thermal history resulting from selective laser melting leads to microstructural characteristics and residual stresses that have considerable impact on the mechanical behavior of the printed part. Accurate measurements of the temperature combined with thermal models are needed to better understand and control the thermal history to optimize mechanical properties. In order to calibrate and validate models, experimental temperature data must be accurately measured in a rapid fashion due to the high speeds of the laser. In this work, a novel method to read data from thermocouples is created with enhanced circuitry that achieves a sampling rate of 10 kHz. This data acquisition rate allows for high precision sampling of SLM heating and cooling cycles.

additive manufacturing↗
NASA NTRS1989

Report on the multicolor pyrometry session at the Second NASA Non-Contact Temperature-Measurement Workshop

The session met jointly with the other special sessions. Due to time constraints, the concerns of multicolor pyrometry were not addressed in depth. Multicolor pyrometry attempts to determine an object's temperature and emittance as a function of wavelength from simultaneous measurement of the spectral radiance of the object at multiple wavelengths. The main issues are those of the most appropriate model for the wavelength dependence of the emittance, the number of undetermined parameters, and the error in the measured temperature. It has long been known that it is inappropriate to attempt to model the emittance with a functional form that contains as many unknowns as wavelengths. Such attempts will lead to gross errors in the measured temperature. However, more recent work by Hunter and Khan has indicated that emittance can be modeled by a function with many fewer degrees of freedom than sampled wavelengths (e.g., it may be appropriate to use a second order polynomial to fit data from a forty-color pyrometer). In a platform lecture, Khan described algorithms for determination of the parameters by minimization of the errors between the model and the data in a least-squares sense. The first was a linear method and the second was a non-linear method where the emittance could assume any functional form. Both methods were shown to be very sensitive to random noise and non-linearity in the measurement system.

Spjut, R. Erik↗
NASA NTRS1990

CARS temperature measurements in a hypersonic propulsion test facility

Static-temperature measurements performed in a reacting vitiated air-hydrogen Mach-2 flow in a duct in Test Cell 2 at NASA LaRC by using a coherent anti-Stokes Raman spectroscopy (CARS) system are discussed. The hypersonic propulsion Test Cell 2 hardware is outlined with emphasis on optical access ports and safety features in the design of the Test Cell. Such design considerations as vibration, noise, contamination from flow field or atmospheric-borne dust, unwanted laser- and electrically-induced combustion, and movement of the sampling volume in the flow are presented. The CARS system is described, and focus is placed on the principle and components of system-to-monochromator signal coupling. Contour plots of scramjet combustor static temperature in a reacting-flow region are presented for three stations, and it is noted that the measurements reveal such features in the flow as maximum temperature near the model wall in the region of the injector footprint.

Jarrett, O., Jr.↗
NASA NTRS1989

Non-contact temperature measurement requirements

The Marshall Space Flight Center is involved with levitation experiments for Spacelab, Space Station, and drop tube/tower operations. These experiments have temperature measurement requirements, that of course must be non-contact in nature. The experiment modules involved are the Acoustic Levitator Furnace (ALF), and the Modular Electromagnetic Levitator (MEL). User requirements of the ALF and drop tube are presented. The center also has temperature measurement needs that are not microgravity experiment oriented, but rather are related to the propulsion system for the STS. This requirement will also be discussed.

Higgins, D. B.↗
NASA NTRS1984

Furthur development of the dynamic gas temperature measurement system

Candidate concepts capable of generating dynamic temperatures were identified and analyzed for use in verifying experimentally the frequency response of the dynamic gas temperature measurement system. A rotating wheel concept and one other concept will be selected for this purpose. Modifications to the data reduction code algorithms developed were identified and evaluated to reduce substantially the data reduction execution time. These modifications will be incorporated in a new data reduction program to be written in FORTRAN IV.

Elmore, D. L.↗
NASA NTRS1992

Birefringence-balanced polarimetric optical fiber sensor for high-temperature measurements

A birefringence-balanced polarimetric multimode fiber temperature sensor is proposed and demonstrated. Two single-crystal sapphire rods are incorporated into the sensor head. They are connected end to end in such a way that the slow axis of the first rod is aligned with the fast axis of the second rod, referred to as the referencing rod. Since the lengths of the two rods are chosen to be almost the same, the original birefringence of the first rod is balanced by that of the second rod. A light-emitting diode serves as the light source. This sensor has been experimentally demonstrated for high-temperature measurements as high as 1500 C. A sensitivity of 5 C has been obtained.

Wang, Anbo↗
NASA NTRS1978

Surface temperature measurements in rolling and sliding EHD contacts

In this study, moving surface temperature measurements in rolling and sliding EHD point contacts were made using an available infrared technique. Film thickness and traction have also been measured. Slide-to-roll ratios of -2 to +2 have been studied. By using a different kinematic configuration, stationary surface temperatures have also been measured. It has been shown that, while surface temperature rises in the low slip region are relatively small, stationary surface temperatures are significantly higher than the moving surface temperatures. Flash temperature theory has been extended to cover the combined rolling and sliding conditions. Correlation between the predicted and the measured values has also been performed.

Nagaraj, H. S.↗
NASA NTRS2002

Heated Surface Temperatures Measured by Infrared Detector in a Cascade Environment

Investigators have used infrared devices to accurately measure heated surface temperatures. Several of these applications have been for turbine heat transfer studies involving film cooling and surface roughness, typically, these measurements use an infrared camera positioned externally to the test section. In cascade studies, where several blades are used to ensure periodic flow, adjacent blades block the externally positioned camera's views of the test blade. To obtain a more complete mapping of the surface temperatures, researchers at the NASA Glenn Research Center fabricated a probe with an infrared detector to sense the blade temperatures. The probe size was kept small to minimize the flow disturbance. By traversing and rotating the probe, using the same approach as for total pressure surveys, one can find the blade surface temperatures. Probe mounted infrared detectors are appropriate for measuring surface temperatures where an externally positioned infrared camera is unable to completely view the test object. This probe consists of a 8-mm gallium arsenide (GaAs) lens mounted in front of a mercury-cadmium-zinc-tellurium (HgCdZnTe) detector. This type of photovoltaic detector was chosen because of its high sensitivity to temperature when the detector is uncooled. The particular application is for relatively low surface temperatures, typically ambient to 100 C. This requires a detector sensitive at long wavelengths. The detector is a commercial product enclosed in a 9-mm-diameter package. The GaAs lens material was chosen because of its glass-like hardness and its good long-wavelength transmission characteristics. When assembled, the 6.4-mm probe stem is held in the traversing actuator. Since the entire probe is above the measurement plane, the flow field disturbance in the measurement plane is minimized. This particular probe body is somewhat wider than necessary, because it was designed to have replaceable detectors and lenses. The signal for the detector is fed through the hollow probe body. The detector's signal goes to an externally mounted preamplifier. The detector assembly, along with a preamplifier, is calibrated as a function of the surface temperature for various detector temperatures. The output voltage is a function of both the detector and object temperatures.

Boyle, Robert J.↗
NASA NTRS1990

Temperature measurements of a high-power microwave feedhorn window

Temperature measurements of a high-power microwave feedhorn window, obtained using an imaging IR radiometer during transmitter operation at 365 kW CW and 8.5 GHz, are discussed. The window under investigation was constructed of HTP-6, a high-thermal-performance material developed to shield the Space Shuttle Orbiter from the heat of reentry. The measurement technique is described, and experimental results are presented. The window performed adequately at 365 kW CW with a center temperature of 475 C. The tests verify that HTP-6 can be used as a window material or a support structure in high-power waveguides at power densities of 1.47 kW/sq cm for extended periods of time, with no change in its mechanical characteristics.

Hoppe, Daniel J.↗