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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 NTRS1980

Automatic control of NASA Langley's 0.3-meter cryogenic test facility

Experience during the past 6 years of operation of the 0.3-meter transonic cryogenic tunnel at the NASA Langley Research Center has shown that there are problems associated with efficient operation and control of cryogenic tunnels using manual control schemes. This is due to the high degree of process crosscoupling between the independent control variables (temperature, pressure, and fan drive speed) and the desired test condition (Mach number and Reynolds number). One problem has been the inability to maintain long-term accurate control of the test parameters. Additionally, the time required to change from one test condition to another has proven to be excessively long and much less efficient than desirable in terms of liquid nitrogen and electrical power usage. For these reasons, studies have been undertaken to: (1) develop and validate a mathematical model of the 0.3-meter cryogenic tunnel process, (2) utilize this model in a hybrid computer simulation to design temperature and pressure feedback control laws, and (3) evaluate the adequacy of these control schemes by analysis of closed-loop experimental data. This paper will present the results of these studies.

Thibodeaux, J. J.↗
NASA NTRS2018

Developing Controlled Conductive Boundaries for JWST Cryogenic Testing

In 2017, the James Webb Space Telescope (JWST) underwent functional testing and optical metrology verification of the combined Optical Telescope Element and Integrated Science Instrument Module (OTIS) under cryogenic vacuum conditions in Chamber A at the Johnson Space Center. Maintaining flight-like thermal boundary conditions was a critical requirement for optical testing and required unique and challenging Ground Support Equipment (GSE) design solutions. Two such GSE systems, the Integrated Science Instrument Module (ISIM) Precool Straps and the Hardpoint Struts were direct conduction interfaces to the flight hardware. Hardware safety during cooldown required detailed design of their conductivity, and thermal balance testing required "zero-Q" (0-Q) heater implementation to bring the heat flow to zero, thereby cutting off these non-flight conductive links after operating temperatures were achieved. This paper describes the design considerations and approach implemented to achieve the required flight hardware cool down and return to ambient conditions, ensure flight hardware safety, and minimize the non-flight-like heat flows to or from the observatory during cryo-stable testing.

Cooke, D.↗
NASA NTRS2018

Developing Controlled Conductive Boundaries for JWST Cryogenic Testing

In 2017, the James Webb Space Telescope (JWST) underwent functional testing and optical metrology verification of the combined Optical Telescope Element and Integrated Science Instrument Module (OTIS) under cryogenic vacuum conditions in Chamber A at the Johnson Space Center. Maintaining flight-like thermal boundary conditions was a critical requirement for optical testing and required unique and challenging Ground Support Equipment (GSE) design solutions. Two such GSE systems, the Integrated Science Instrument Module (ISIM) Precool Straps and the Hardpoint Struts were direct conduction interfaces to the flight hardware. Hardware safety during cooldown required detailed design of their conductivity, and thermal balance testing required zero-Q (0-Q) heater implementation to bring the heat flow to zero, thereby cutting off these non-flight conductive links after operating temperatures were achieved. This paper describes the design considerations and approach implemented to achieve the required flight hardware cool down and return to ambient conditions, ensure flight hardware safety, and minimize the non-flight-like heat flows to or from the observatory during cryo-stable testing.

Cooke, Dwight A.↗
NASA NTRS1992

Cryogenic testing of a foam-multilayer insulation concept in a simulated prelaunch environment

NASA-Marshall has devised an upper-stage vehicle-applicable reusable cryogenic insulation thermal-control system which employs spray-on foam insulation (SOFI) that is attached to the cryotank wall and covered by 17-sheet multilayer insulation composed of double-aluminized mylar and Dacron scrim. Four prelaunch test simulations have been conducted for the case of LH2 with gaseous N2 purge gas. Test results indicate that the SOFI surface temperature was sufficiently high to preclude atmospheric oxygen and nitrogen liquefaction.

Martin, James J.↗
NASA NTRS1992

Cryogenic test rig with an aerodynamic magnetically levitated carriage

The results are presented of the studies which concern the use of a magnetically levitated aerodynamic carriage with a model moving in a closed cryogenic channel. The facility dimensions are established, operating ranges are calculated, thermal isolation, cooling and measurement systems are described, comparison of this facility with wind tunnels is given and its advantages are shown.

Borisov, Sergey YU.↗
NASA NTRS1989

Unpressurized Container For Cryogenic Testing

Unpressurized cryostat makes mechanical testing of materials at low temperature more convenient. Maintains specimens at temperatures of -400 to -450 degree F without sealing them in gastight, vacuum-insulated container. Easy to insert and remove specimens and attach instrumentation wiring to them. Vents vapor continuously, so no danger of buildup of internal pressure from evaporating cryogenic liquid. Includes two concentric chambers with stainless-steel walls and fiber insulation. Specimen mounted in inner chamber, and such instruments as extensometers and thermocouples attached. Loose lid of polystyrene foam or other suitable material placed over vessel.

Walker, Susan B.↗
NASA NTRS1967

Environmental control system for cryogenic testing of tensile specimens

Environmental control system uses a special coil to permit the tensile testing of specimens which may be subjected to temperatures anywhere between liquid nitrogen and room temperature. The test specimen zone is surrounded by the coil which permits the selective flooding of the specimen with warm or cold gas.

Vandergrift, E. F.↗
NASA NTRS1980

Modified displacement gage for cryogenic testing

Modification of double-cantilever-beam resistance strain gage makes boiling of hydrogen on gage arms less of problem. Modified gages are encapsulated nickel/chromium alloy, and bridge-excitation voltage is reduced from 10 to 1.5 volts. Sensitivity is 1.0 millivolt per inch with 1.5 volt excitation.

Pierce, W. S.↗
NASA NTRS1982

Cryogenic testing of mirrors for infrared space telescopes

The Shuttle IR Telescope Facility (SIRTF) test apparatus can test candidate mirror materials as large as 66 cm in diameter, at temperatures as low as about 10 K, and is accurate enough to detect optical figure changes as small as a fraction of a wavelength from the room temperature figure. The fused silica mirrors currently undergoing testing in the SIRTF are sunk into a liquid He reservoir with copper straps, whose individual strands are soldered to small silver spots diffused throughout the unfigured side of the mirror to accomplish fast conductive cooling. Optical access to the cold mirror is by means of a small glass port in the vacuum chamber. An interferometer is used to examine the mirror figure throughout the cool-down. Interferograms are photographed, fringe patterns are digitized, and mirror figure contour plots are calculated by means of a computer.

Miller, J. H.↗
NASA NTRS1993

Cryogenic testing of a foam-multilayer insulation concept in a simulated orbit hold environment

Foam multilayer insulation (FMLI), a reusable thermal control system (TCS), was evaluated in a simulated orbit hold environment on a test tank of 3.0 ft diameter, 5.6 ft length, and 34.5 cu ft volume. The TCS consisted of a 0.44-inch thick foam and a 16-layer (17 sheet) MLI blanket attached to the tank barrel and lower bulkhead, with the upper bulkhead covered with a 2.7-inch foam and a 31-layer (32 sheets) MLI blanket. Average insulation heating rates during orbit hold simulations ranged from 10.5 to 28.1 Btu/hr for warm boundary temperatures from 300 to 460 R, respectively. These rates corresponded to liquid losses of 0.9 and 2.3 percent of the tank's volume per day. This liquid loss rate would be significantly reduced for full size vehicle tanks due to the decreased surface area-to-volume ratio as compared to the test tank.

Martin, James J.↗
NASA NTRS2011

Helium-Cooled Black Shroud for Subscale Cryogenic Testing

This shroud provides a deep-space simulating environment for testing scaled-down models of passively cooling systems for spaceflight optics and instruments. It is used inside a liquid-nitrogen- cooled vacuum chamber, and it is cooled by liquid helium to 5 K. It has an inside geometry of approximately 1.6 m diameter by 0.45 m tall. The inside surfaces of its top and sidewalls have a thermal absorptivity greater than 0.96. The bottom wall has a large central opening that is easily customized to allow a specific test item to extend through it. This enables testing of scale models of realistic passive cooling configurations that feature a very large temperature drop between the deepspace-facing cooled side and the Sun/Earth-facing warm side. This shroud has an innovative thermal closeout of the bottom wall, so that a test sample can have a hot (room temperature) side outside of the shroud, and a cold side inside the shroud. The combination of this closeout and the very black walls keeps radiated heat from the sample s warm end from entering the shroud, reflecting off the walls and heating the sample s cold end. The shroud includes 12 vertical rectangular sheet-copper side panels that are oriented in a circular pattern. Using tabs bent off from their edges, these side panels are bolted to each other and to a steel support ring on which they rest. The removable shroud top is a large copper sheet that rests on, and is bolted to, the support ring when the shroud is closed. The support ring stands on four fiberglass tube legs, which isolate it thermally from the vacuum chamber bottom. The insides of the cooper top and side panels are completely covered with 25- mm-thick aluminum honeycomb panels. This honeycomb is painted black before it is epoxied to the copper surfaces. A spiral-shaped copper tube, clamped at many different locations to the outside of the top copper plate, serves as part of the liquid helium cooling loop. Another copper tube, plumbed in a series to the top plate s tube, is clamped to the sidewall tabs where they are bolted to the support ring. Flowing liquid helium through these tubes cools the entire shroud to 5 K. The entire shroud is wrapped loosely in a layer of double-aluminized Kapton. The support ring s inner diameter is the largest possible hole through which the test item can extend into the shroud. Twelve custom-sized trapezoidal copper sheets extend inward from the support ring to within a few millimeters of the test item. Attached to the inner edge of each of these sheets is a custom-shaped strip of Kapton, which is aluminum- coated on the warm-facing (outer) side, and has thin Dacron netting attached to its cold-facing side. This Kapton rests against the test item, but the Dacron keeps it from making significant thermal contact. The result is a non-contact, radiatively reflective thermal closeout with essentially no gap through which radiation can pass. In this way, the part of the test item outside the shroud can be heated to relatively high temperatures without any radiative heat leaking to the inside.

Tuttle, James↗
NASA NTRS2012

James Webb Space Telescope Integrated Science Instrument Module Calibration and Verification of High-Accuracy Instrumentation to Measure Heat Flow in Cryogenic Testing

The James Webb Space Telescope (JWST) is an upcoming flagship observatory mission scheduled to be launched in 2018, Three of the four science instruments are passively cooled to their operational temperature range of 36K to 40K, and the fourth instrument is actively cooled to its operational temperature of approximately 6K. The requirement for multiple thermal zones results in the instruments being thermally connected to five external radiators via individual high purity aluminum heat straps. Thermal-vacuum and thermal balance testing of the flight instruments at the Integrated Science Instrument Module (ISIM) element level will take place within a newly constructed shroud cooled by gaseous helium inside Goddard Space Flight Center's (GSFC) Space Environment Simulator (SES). The flight external radiators are not available during ISIM-Ievel thermal vacuum/thermal testing, so they will be replaced in test with stable and adjustable thermal boundaries with identical physical interfaces to the flight radiators. Those boundaries are provided on specially designed test hardware which measures the heat flow within each of the five heat straps to an accuracy of less than 2 m W, which is less than 5% of the minimum predicted heat flow values. This is essential to ISIM thermal model correlation, since thermal models are more accurately correlated when temperature data is supplemented by accurate knowledge of heat flows. Devices that measure heat flow in this manner have historically been referred to as "Q-meters". Perhaps the most important feature of the design of the Q-meters is that it does not depend on the absolute accuracy of its temperature sensors, but rather on a difference in heater power, for which a table is empirically developed during a calibration campaign in a small chamber at GSFC. This paper discusses the Q-meter calibration procedure including calibration chamber modifications and accommodations, the handling of differing conditions between calibration and usage, the calibration process itself, and the results of the tests used to determine if the calibration is successful.

Comber, Brian↗
NASA NTRS2012

James Webb Space Telescope Integrated Science Instrument Module Calibration and Verification of High-Accuracy Instrumentation to Measure Heat Flow in Cryogenic Testing

The James Webb Space Telescope (JWST) is an upcoming flagship observatory mission scheduled to be launched in 2018. Three of the four science instruments are passively cooled to their operational temperature range of 36K to 40K, and the fourth instrument is actively cooled to its operational temperature of approximately 6K. The requirement for multiple thermal zoned results in the instruments being thermally connected to five external radiators via individual high purity aluminum heat straps. Thermal-vacuum and thermal balance testing of the flight instruments at the Integrated Science Instrument Module (ISIM) element level will take place within a newly constructed shroud cooled by gaseous helium inside Goddard Space Flight Center's (GSFC) Space environment Simulator (SES). The flight external radiators are not available during ISIM-level thermal vacuum/thermal testing, so they will be replaced in test with stable and adjustable thermal boundaries with identical physical interfaces to the flight radiators. Those boundaries are provided by specially designed test hardware which also measures the heat flow within each of the five heat straps to an accuracy of less than 2 mW, which is less than 5% of the minimum predicted heat flow values. Measurement of the heat loads to this accuracy is essential to ISIM thermal model correlation, since thermal models are more accurately correlated when temperature data is supplemented by accurate knowledge of heat flows. It also provides direct verification by test of several high-level thermal requirements. Devices that measure heat flow in this manner have historically been referred to a "Q-meters". Perhaps the most important feature of the design of the JWST Q-meters is that it does not depend on the absolute accuracy of its temperature sensors, but rather on knowledge of precise heater power required to maintain a constant temperature difference between sensors on two stages, for which a table is empirically developed during a calibration campaign in a small chamber at GSFC. This paper provides a brief review of Q-meter design, and discusses the Q-meter calibration procedure including calibration chamber modifications and accommodations, handling of differing conditions between calibration and usage, the calibration process itself, and the results of the tests used to determine if the calibration is successful.

Comber, Brian↗
NASA NTRS2017

Guarded Flat Plate Cryogenic Test Apparatus and Calorimeter

A test apparatus for thermal energy measurement of disk-shaped test specimens has a cold mass assembly locatable within a sealable chamber with a guard vessel having a guard chamber to receive a liquid fluid and a bottom surface to contact a cold side of a test specimen, and a test vessel having a test chamber to receive a liquid fluid and encompassed on one side by a center portion of the bottom surface shared with the guard vessel. A lateral wall assembly of the test vessel is closed by a vessel top, the lateral wall assembly comprising an outer wall and an inner wall having opposing surfaces that define a thermal break including a condensable vapor pocket to inhibit heat transfer through the lateral wall from the guard vessel to the test vessel. A warm boundary temperature surface is in thermal communication with a lower surface of the test specimen.

Fesmire, James E.↗
NASA NTRS2018

Guarded Flat Plate Cryogenic Test Apparatus and Calorimeter (C-600)

A test apparatus for thermal energy measurement of disk-shaped test specimens has a cold mass assembly locatable within a sealable chamber with a guard vessel having a guard chamber to receive a liquid fluid and a bottom surface to contact a cold side of a test specimen, and a test vessel having a test chamber to receive a liquid fluid and encompassed on one side by a center portion of the bottom surface shared with the guard vessel. A lateral wall assembly of the test vessel is closed by a vessel top, the lateral wall assembly comprising an outer wall and an inner wall having opposing surfaces that define a thermal break including a condensable vapor pocket to inhibit heat transfer through the lateral wall from the guard vessel to the test vessel. A warm boundary temperature surface is in thermal communication with a lower surface of the test specimen.

Fesmire, James E.↗
NASA NTRS2023

Fitting Leak Test Report: Ground-Based Cryogenic Leak Test of Fittings for Cryogenic Fluid Management

EXECUTIVE SUMMARY Mechanically connected joints used in cryogenic fluid lines as part of space flight elements need to survive launch vibrations and remain leak-free to minimize the loss of on-board commodity and hazardous gas accumulation. In 2020, a cryogenic test apparatus was developed which can evaluate the leak performance of pressurized threaded fluid fittings. The fittings were mounted in the TVAC and cooled to cryogenic test temperature and pressurized with helium while the leak rate was measured using a calibrated GHe leak detector. The test articles for the initial proof of concept testing were ¼ and 1 inch Swagelok VCR fittings with three different types of seal rings copper, nickel, and Ni. Each fitting configuration (size/seal material) was subjected to two consecutive cryogenic thermal cycles, followed by exposure to a launch vibration profile at ambient temperature, after which two additional TVAC cycle tests were performed. The testing reported here is a continuation of the 2020 tests with a statistically significant large number of samples and test runs. Three Swagelok VCR fitting sizes were tested ¼, ½ and 1 inch, and five (5) samples of each fitting size, each sample was tested with SST and Ni seal rings (Total of 30 unique test articles). Each test article was subjected to four (4) thermal cycles. Half of these cycles were performed before vibration testing and half were performed after vibration testing. The vibration testing was performed to evaluate the ability of the fittings to survive launch-type vibration profiles and remain leak-free. Leak checking of each fitting was completed at temperatures between 20K – 30K. The test procedure in Section 8.0 was designed to facilitate a qualification test program by allowing a higher test throughput rate coupled with repeatable test profiles. Results were very positive and show that out of the 30 samples they all passed with leak rates a factor of 2-3 lower than the established 10-6sccs GHe leak threshold. The result showed the Ni seals had lower leak rate, but the SST was more rugged. There were two deviations where damage to the Ni seal ring during assembly resulted in a leaky fitting, this is discussed in Section 10.7 Test Deviations. These fittings show great promise for space flight use and further testing is recommended to fully qualify the fittings per the ASTM F1387-19 and/or other relevant NASA specifications. The test equipment hardware and software capability developed for this testing is generic and not restricted to VCR fittings. It can be employed to evaluate/qualify the leak performance of other types of fittings and a wide range of other cryogenic fluid components such as valves, gages, connectors, etc.

Cryogenic↗