SEARCH · Engineering Papers

Results for “THERMOCOUPLES”

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.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,063 records · Page 59

All sources NASA NTRS DOE OSTI

NASA NTRS1976

Measurements of spectral and total emittance of reinforced carbon-carbon

Elevated temperature measurements of the spectral emittance of reinforced carbon-carbon (RCC) as the thermal protection material for the leading edge areas of the Space Shuttle Orbiter were carried out in situ, with environments provided by arc-heated streams of air and argon. A monochromator, infrared pyrometers, and thermocouples were used in evaluating the response of the RCC test specimens during the emittance measurements. Results indicate that the material is nongray, with lowest spectral emittance at the short wavelengths and with relatively high total emittance. The trend of the total emittance data suggests a slight decrease in total emittance with increasing temperature, although the emittance value stabilizes with continuing exposure.

Grinberg, I. M.↗

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 NTRS1976

Soil water content and evaporation determined by thermal parameters obtained from ground-based and remote measurements

Soil water contents from both smooth and rough bare soil were estimated from remotely sensed surface soil and air temperatures. An inverse relationship between two thermal parameters and gravimetric soil water content was found for Avondale loam when its water content was between air-dry and field capacity. These parameters, daily maximum minus minimum surface soil temperature and daily maximum soil minus air temperature, appear to describe the relationship reasonably well. These two parameters also describe relative soil water evaporation (actual/potential). Surface soil temperatures showed good agreement among three measurement techniques: in situ thermocouples, a ground-based infrared radiation thermometer, and the thermal infrared band of an airborne multispectral scanner.

Reginato, R. J.↗

NASA NTRS1976

Infrared pyrometer for high resolution surface temperature measurements on rotating turbine blades

A high resolution pyrometer was developed and used to obtain temperature profiles of rotating turbine blades at tip speeds up to 366 meters per second (1200 fps). Surface temperature variations from 920 to 1250 K (1200 to 1800 F) can be measured and variations over distances of 0.05 cm (0.020 in.) can be resolved. Temperature profiles were obtained in near real time as hard copies from a computer display terminal. Temperatures measured with the prototype pyrometer and with thermocouples agreed to within 2 percent over the temperature range from 977 to 1144 K (1300 to 1600 F).

Uguccini, O. W.↗

NASA NTRS1976

Aeroheating model advancements featuring electroless metallic plating

Discussed are advancements in wind tunnel model construction methods and hypersonic test data demonstrating the methods. The general objective was to develop model fabrication methods for improved heat transfer measuring capability at less model cost. A plated slab model approach was evaluated with cast models containing constantan wires that formed single-wire-to-plate surface thermocouple junctions with a seamless skin of electroless nickel alloy. The surface of a space shuttle orbiter model was selectively plated with scaled tiles to simulate, with high fidelity, the probable misalignments of the heatshield tiles on a flight vehicle. Initial, Mach 8 heating results indicated a minor effect of tile misalignment roughness on boundary layer transition, implying a possible relaxation of heatshield manufacturing tolerances. Some loss of the plated tiles was experienced when the model was tested at high heating rates.

Stalmach, C. J., Jr.↗

NASA NTRS1978

Ablative liner locates hotspots

Ablative liner quantifies local-heating effects in combustion chambers and other applications. By identifying hotspots and helping to map heat-flux patterns, liner is useful tool for research in engine design. Liner permanently records heat flux at each point by depth of ablation due to local heating. Technique determines best locations for thermocouples for more extensive testing.

Mercer, S. D.↗

NASA NTRS1976

Experimental clean combustor program: Noise study

Under a Noise Addendum to the NASA Experimental Clean Combustor Program (ECCP) internal pressure fluctuations were measured during tests of JT9D combustor designs conducted in a burner test rig. Measurements were correlated with burner operating parameters using an expression relating farfield noise to these parameters. For a given combustor, variation of internal noise with operating parameters was reasonably well predicted by this expression but the levels were higher than farfield predictions and differed significantly among several combustors. For two burners, discharge stream temperature fluctuations were obtained with fast-response thermocouples to allow calculation of indirect combustion noise which would be generated by passage of the temperature inhomogeneities through the high pressure turbine stages of a JT9D turbofan engine. Using a previously developed analysis, the computed indirect combustion noise was significantly lower than total low frequency core noise observed on this and several other engines.

Sofrin, T. G.↗

NASA NTRS1976

Results from a convective heat transfer rate distribution test on a 0.0175 scale model (22-0) of the Rockwell International vehicle 4 space shuttle configuration in the AEDC-VKF tunnel B (OH49B), volume 1

The tests were conducted in a hypersonic wind tunnel at Mach number 8 to investigate reentry mode convective heat--transfer rates to the vehicle 4 shuttle orbiter. The thin skin thermocouple technique was used to obtain the heat transfer rate measurements. A complete set of tabulated data is presented.

Herrera, B. J.↗

NASA NTRS1976

Heat-transfer distributions on a 0.013-scale shuttle solid rocket booster at Mach 3.70 and angles of attack from 0 deg to 180 deg

An experimental investigation was conducted in the Langley Unitary Plan wind tunnel to estimate the peak aerodynamic heating on the space shuttle solid rocket booster during the descent phase of its flight. Heat transfer measurements were obtained using 0.013 scale models instrumented with thermocouples at a Mach number of 3.70, Reynolds number per meter of 11.48 million, and angles of attack from 0 to 180 deg. At angles of attack of 0 and 180 deg, heat transfer measurements on the cylindrical section of the model between the conical nose and ring interaction region were in good agreement with flat plate strip theory for laminar and turbulent flow. At angles of attack up to 30 deg, measurements on this section of the model were in good agreement with laminar swept-cylinder theory, whereas at angles of attack from 120 to 180 deg, the measurements were in good agreement with turbulent swept-cylinder theory. The good agreement with turbulent theory indicated that large flow disturbances created by the nozzle and afterbody flare at these large angles of attack influenced the downstream heating primarily by promoting boundary layer transition. Measurements obtained at 90 deg angle of attack were indicative of laminar flow.

Lamb, M.↗

NASA NTRS1977

Heat-transfer test results for a .0275-scale space shuttle external tank with a 10 deg/40 deg double cone-ogive nose in the NASA/AMES 3.5-foot hypersonic wind tunnel (FH14), volume 2

A .0275 scale forebody model of the new baseline configuration of the space shuttle external tank vent cap configuration was tested to determine the flow field due to the double cone configuration. The tests were conducted in a 3.5 foot hypersonic wind tunnel at alpha = -5 deg, -4.59 deg, 0 deg, 5 deg, and 10 deg; beta = 0 deg, -3 deg, -5.51 deg, -6 deg, -9 deg, and +6 deg; nominal freestream Reynolds numbers per foot of 1.5 x 1 million, 3.0 x 1 million, and 5.0 x 1 million; and a nominal Mach number of 5. Separation and reattached flow from thermocouple data, shadowgraphs, and oil flows indicate that separation begins about 80% from the tip of the 10 deg cone, then reattaches on the vent cap and produces fully turbulent flow over most of the model forebody. The hardware disturbs the flow over a much larger area than present TPS application has assumed. A correction to the flow disturbance was experimentally suggested from the results of an additional test run.

Carroll, H. R.↗

NASA NTRS1977

Apparatus for determining thermophysical properties of test specimens

Apparatus is described for directly measuring the quantity square root of pck of a test specimen such as a wind tunnel model where p is density, c is the specific heat and k is the thermal conductivity of the specimen. The test specimen and a reference specimen are simultaneously subjected to the heat from a heat source. A thermocouple is attached to the reference specimen for producing a first electrical analog signal proportional to the heat rate Q that the test specimen is subjected to and an infrared radiometer that is aimed at the test specimen produces a second electrical analog signal proportional to the surface temperature T of the test specimen. An analog-to-digital converter converts the first and second electrical analog signals to digital signals. These digital signals are applied to a computer for determining the quantity.

Creel, T. R., Jr.↗

NASA NTRS1977

A low cost, portable instrument for measuring emittance

A low cost, portable instrument was developed with which emittance can be measured by comparison to a standard. A reflector collects infrared radiation from a heated sample onto a low mass, black detector and the temperature rise of the black detector is measured with a thermocouple and meter. Graphical examples are presented for determination of emittance from measurements made on a sample at any known temperature.

Mcdonald, G.↗

NASA NTRS1977

Experimental investigation of flow turbulence effects on premixed methane-air flames

An experimental assessment of a novel technique for measuring turbulent flame speeds was conducted. Unconfined, V-shaped, methane-air flames stabilized in grid turbulence were investigated. Local flame speeds were measured employing hot film and laser anemometry and fine wire thermocouples. The measurement instrumentation was extended to provide mean and fluctuating temperature information about turbulent flames. The flames in grid turbulence exhibited an increase in flame speed with increased length scale and velocity fluctuations. At high combustor velocities, stabilizer wake turbulence dominated the flame properties.

Smith, K. O.↗

NASA NTRS1976

Effect of ambient temperature on the thermal profile of the human forearm, hand, and fingers

Forearm, hand, and finger skin temperatures were measured on the right and left sides of seven resting men. The purpose was to determine the bilateral symmetry of these segmental temperature profiles at ambient temperatures from 10 to 45 C. Thermistors placed on the right and left forearms, hands, and index fingers were used to monitor the subjects until equilibration was reached at each ambient temperature. Additionally, thermal profiles of both hands were measured with copper-constantan thermocouples. During one experimental condition (23 C ambient), rectal, ear canal, and 24 skin temperatures were measured on each subject. Average body and average skin temperatures are given for each subject at the 23 C ambient condition. Detailed thermal profiles are also presented for the dorsal, ventral, and circumferential left forearm, hand, and finger skin temperatures at 23 C ambient. No significant differences were found between the mean skin temperatures of the right and left contralateral segments at any of the selected ambient temperatures.

Montgomery, L. D.↗

NASA NTRS1978

Controlled freezing of biological samples

Apparatus consists of thermocouple connected to semiconductor reference junction. Junction is connected to amplifier that boosts signal by 1,000. High-level signal is displayed on recorder and fed into second amplifier where it is compared with signal from potentiometer of programmed dc reference in bag-temperature programer. Difference in signals indicates output voltage. Remaining circuitry provides zero-phase, time-proportion control of heaters such that heater power is directly proportional to error signal.

Cygnarowicz, T. A.↗

NASA NTRS1978

Body/bone-marrow differential-temperature sensor

Differential-temperature sensor developed to compare bone-marrow and body temperature in leukemia patients uses single stable amplifier to monitor temperature difference recorded by thermocouples. Errors are reduced by referencing temperatures to each other, not to separate calibration points.

Anselmo, V. J.↗

NASA NTRS1978

Calibration target for temperature radiometer

Technique measures temperature/voltage drop characteristics of very thin filament. With constant current running through filament, voltage drop is recorded at various temperatures, as measured by calibrated thermocouple.

Edwards, S. F.↗

NASA NTRS1978

Predicting surface heat flux

Report presents technique involving single embedded thermocouple used to predict flux and temperature for high-or-low conductivity materials that have temperature-and-pressure dependent properties. Technique solves for heat rate and temperature at given surface at each time step, rather than for entire history. Newton-Raphson technique is used for temperature solutions; then quadratic fit is employed. Report contains representative graphs and tables.

Curry, D. M.↗