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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 127 records · Page 7

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NASA NTRS1992

Thick strings, the liquid crystal blue phase, and cosmological large-scale structure

A phenomenological model based on the liquid crystal blue phase is proposed as a model for a late-time cosmological phase transition. Topological defects, in particular thick strings and/or domain walls, are presented as seeds for structure formation. It is shown that the observed large-scale structure, including quasi-periodic wall structure, can be well fitted in the model without violating the microwave background isotropy bound or the limits from induced gravitational waves and the millisecond pulsar timing. Furthermore, such late-time transitions can produce objects such as quasars at high redshifts. The model appears to work with either cold or hot dark matter.

Luo, Xiaochun↗

NASA NTRS1995

High Temperature Superconducting Bearings for Lunar Telescope Mounts

A telescope to be installed on the lunar surface in the near future must work in a cold and dusty vacuum environment for long periods without on site human maintenance. To track stars, the drive mechanism must be capable of exceedingly fine steps and repeatability. Further, the use of lightweight telescopes for obvious economic benefits burdens the requirement for stable support and rotation. Conventional contact bearings and gear drives have numerous failure modes under such a restrictive and harsh environment. However, hybrid superconducting magnetic bearings (HSMB) fit in naturally. These bearings are stable, light, passive, and essentially frictionless, allowing high precision electronic positioning control. By passive levitation, the HSMB does not wear out and requires neither maintenance nor power. A prototype illustrating the feasibility of this application is presented.

Lamb, Mark↗

NASA NTRS2002

Space Mechanisms Technology Workshop

The Mechanical Components Branch at NASA Glenn Research Center hosted a workshop on Tuesday, May 14, 2002, to discuss space mechanisms technology. The theme for this workshop was 'Working in the Cold,' a focus on space mechanisms that must operate at low temperatures. We define 'cold' as below -60C (210 K), such as would be found near the equator of Mars. However, we are also concerned with much colder temperatures such as in permanently dark craters of the Moon (about 40 K).

Oswald, Fred B.↗

NASA NTRS2008

Gas in Protoplanetary and Debris Disks: Insights from UV Spectroscopy

Over the last two decades, observations of protoplanetary and debris disks have played an important role in the new field of extrasolar planetary studies. Many are familiar with the extensive work on the cold circumstellar dust present in these disks done using infrared and sub-millimeter photometry and spectroscopy. However. UV spectroscopy has made some unique contributions by probing the elusive but vital gas component in protoplanetary and debris disks. In this talk, I will outline our picture of the evolution of protoplanetary disks and discuss the importance of the gas component. New insights obtained from UV spectroscopy will be highlighted, as well as some new puzzles. Finally, I will touch on upcoming studies of gas in protoplanetary and debris disks, some at UV wavelengths, some at far-IR and sub-mm wavelengths.

Roberge, Aki↗

NASA NTRS1980

Design and cold-air test of single-stage uncooled turbine with high work output

A solid version of a 50.8 cm single stage core turbine designed for high temperature was tested in cold air over a range of speed and pressure ratio. Design equivalent specific work was 76.84 J/g at an engine turbine tip speed of 579.1 m/sec. At design speed and pressure ratio, the total efficiency of the turbine was 88.6 percent, which is 0.6 point lower than the design value of 89.2 percent. The corresponding mass flow was 4.0 percent greater than design.

Moffitt, T. P.↗

NASA NTRS1980

Cold water aquifer storage

A working prototype system is described in which water is pumped from an aquifer at 70 F in the winter time, chilled to a temperature of less than 50 F, injected into a ground-water aquifer, stored for a period of several months, pumped back to the surface in the summer time. A total of 8.1 million gallons of chilled water at an average temperature of 48 F were injected. This was followed by a storage period of 100 days. The recovery cycle was completed a year later with a total of 8.1 million gallons recovered. Approximately 20 percent of the chill energy was recovered.

Reddell, D. L.↗

NASA NTRS1973

Effect of reducing rotor blade inlet diameter on the performance of a 11.66-Centimeter radial-inflow turbine

The effect of increased rotor blade loading on turbine performance was investigated by reducing rotor blade inlet diameter. The reduction was made in four stages. Each modification was tested with the same stator using cold air as the working fluid. Results are presented in terms of equivalent mass flow and efficiency at equivalent design rotative speed and over a range of pressure ratios. Internal flow characteristics are shown in terms of stator exit static pressure and the radial variation of local loss and rotor-exit flow angle with radius ratio. Included are velocity diagrams calculated from the experimental results.

Kofskey, M. G.↗

NASA NTRS1981

Cold-air performance of compressor-drive turbine of Department of Energy upgraded automobile gas turbine engine. 1: Volute-manifold and stator performance

The aerodynamic performance of the inlet manifold and stator assembly of the compressor drive turbine was experimentally determined with cold air as the working fluid. The investigation included measurements of mass flow and stator-exit fluid torque as well as radial surveys of total pressure and flow angle at the stator inlet and annulus surveys of total pressure and flow angle at the stator exit. The stator-exit aftermixed flow conditions and overall stator efficiency were obtained and compared with their design values and the experimental results from three other stators. In addition, an analysis was made to determine the constituent aerodynamic losses that made up the stator kinetic energy loss.

Roelke, R. J.↗

NASA NTRS2010

Testing of Liquid Metal Components for Nuclear Surface Power Systems

The Early Flight Fission Test Facility (EFF-TF) was established by the Marshall Space Flight Center (MSFC) to provide a capability for performing hardware-directed activities to support multiple in-space nuclear reactor concepts by using a non-nuclear test methodology. This includes fabrication and testing at both the module/component level and near prototypic reactor configurations. The EFF-TF is currently supporting an effort to develop an affordable fission surface power (AFSP) system that could be deployed on the Lunar surface. The AFSP system is presently based on a pumped liquid metal-cooled (Sodium-Potassium eutectic, NaK-78) reactor design. This design was derived from the only fission system that the United States has deployed for space operation, the Systems for Nuclear Auxiliary Power (SNAP) 10A reactor, which was launched in 1965. Two prototypical components recently tested at MSFC were a pair of Stirling power conversion units that would be used in a reactor system to convert heat to electricity, and an annular linear induction pump (ALIP) that uses travelling electromagnetic fields to pump the liquid metal coolant through the reactor loop. First ever tests were conducted at MSFC to determine baseline performance of a pair of 1 kW Stirling convertors using NaK as the hot side working fluid. A special test rig was designed and constructed and testing was conducted inside a vacuum chamber at MSFC. This test rig delivered pumped NaK for the hot end temperature to the Stirlings and water as the working fluid on the cold end temperature. These test were conducted through a hot end temperature range between 400 to 550C in increments of 50 C and a cold end temperature range from 30 to 70 C in 20 C increments. Piston amplitudes were varied from 6 to 1 1mm in .5 mm increments. A maximum of 2240 Watts electric was produced at the design point of 550 hot end, 40 C cold end with a piston amplitude of 10.5mm. This power level was reached at a gross thermal efficiency of 28%. A baseline performance map was established for the pair of 1kW Stirling convertors. The performance data will then be used for design modification to the Stirling convertors. The ALIP tested at MSFC has no moving parts and no direct electrical connections to the liquid metal containing components. Pressure is developed by the interaction of the magnetic field produced by the stator and the current which flows as a result of the voltage induced in the liquid metal contained in the pump duct. Flow is controlled by variation of the voltage supplied to the pump windings. Under steady-state conditions, pump performance is measured for flow rates from 0.5-4.3 kg/s. The pressure rise developed by the pump to support these flow rates is roughly 5-65 kPa. The RMS input voltage (phase-to-phase voltage) ranges from 5-120 V, while the frequency can be varied arbitrarily up to 60 Hz. Performance is quantified at different loop temperature levels from 50 C up to 650 C, which is the peak operating temperature of the proposed AFSP reactor. The transient response of the pump is also evaluated to determine its behavior during startup and shut-down procedures.

Polzin, Kurt A.↗

NASA NTRSDate not supplied

Generating Cryogenic Lunar Simulants Within the Planetary Exploration & Astromaterials Research Laboratory

The Planetary Exploration & Astromaterials Research Laboratory (PEARL) aims to provides capabilities for the creation of—and research on—cryogenic lunar regolith simulants (CRS) containing surface volatile analytes. CRS represent regolith samples that might be collected from lunar Permanently Shadowed Regions (PSRs) during future missions. Handling CRS requires procedural and engineering development due to extremely cold (i.e. ≤ - 196°C) working temperatures. However, there is an imperative to understand the physical and chemical alteration of samples during collection, transport, and curation processes throughout the Artemis missions. The chemistries that will be encountered within the PSRs need to be understood based upon prior mission data analysis. The ability to utilize these techniques provides future tests that could be relevant to planetary protection applications regarding future robotic sample return.

Lunar↗

NASA NTRS2024

Durable Antifog Coatings for Spacesuit Helmets

Maintaining a high level of visibility through the helmet of NASA Extravehicular Mobility Unit (EMU) is very difficult under inclement operational conditions. The interior of the helmet bubble will fog up in a high humidity / cold environment with high work rate breathing for extravehicular activity (EVA) that can last up to 8 hours. Currently used wipe on antifog solutions have problems with i) durability, requiring reapplication for every EVA, ii) can potentially get in the astronaut’s eye, impairing their vision, and iii) bottles of solution are a consumable that need to be continuously restocked. Luna Labs has developed a durable, transparent coating that is projected to maintain optical and antifogging properties for the lifetime of the equipment. Luna Labs has leveraged our established Gentoo™ sol-gel coating platform to create a robust, transparent, long-lasting, and antifogging coating. Additionally, the proposed sol-gel coating is thin (2-8 µm), low cost (cents/ft 2 ), and easy to apply while providing excellent abrasion durability and antifogging properties. Luna Labs has produced a coating formulation to possess antifogging properties so that moist air will wet out, forming a microscopically thin sheet of water that does not scatter light. A custom superhydrophilic additive which crosslinks into the durable coating matrix provides superb antifogging properties. This non-scratch transparent coating that will provide continuous antifogging efficacy for >8 hours and environmental durability to last the lifetime of coated component. This technology is relevant to NASA spacesuit applications, as well as for automobiles, aircraft, eyewear, SCUBA masks or any other applications that require transparent antifogging properties.

Spacesuit↗

NASA NTRS1976

Stirling cycle engine and refrigeration systems

A Stirling cycle heat engine is disclosed in which displacer motion is controlled as a function of the working fluid pressure P sub 1 and a substantially constant pressure P sub 0. The heat engine includes an auxiliary chamber at the constant pressure P sub 0. An end surface of a displacer piston is disposed in the auxiliary chamber. During the compression portion of the engine cycle when P sub 1 rises above P sub 0 the displacer forces the working fluid to pass from the cold chamber to the hot chamber of the engine. During the expansion portion of the engine cycle the heated working fluid in the hot chamber does work by pushing down on the engine's drive piston. As the working fluid pressure P sub 1 drops below P sub 0 the displacer forces most of the working fluid in the hot chamber to pass through the regenerator to the cold chamber. The engine is easily combinable with a refrigeration section to provide a refrigeration system in which the engine's single drive piston serves both the engine and the refrigeration section.

Higa, W. H.↗

NASA NTRS2022

HYPERFIRE

The two main sub-scale, ground-based rocket aerodynamics testing techniques – hot-fire testing and cold-flow testing – pose a series of tradeoffs. Hot-fire testing is generally much more accurate, but is often burdensome, costly, and requires long lead times due to design work, infrastructure preparation, etc. Cold-flow testing is much less expensive and has a rapid turnaround time, but conventional simulants (e.g., nitrogen, steam) used in cold-flow testing yield less accurate results (i.e., results that are not sufficiently representative of test article performance). While researching methods to optimize such tradeoffs, engineers at NASA’s Stennis Space Center discovered that ethane can be tuned to approximate rocket exhaust plumes generated by several common rocket propellants. This led NASA to develop the HYdrocarbon Propellants Enabling Reproduction of Flows in Rocket Engines (HYPERFIRE), a sub-scale, non-reacting flow test system. HYPERFIRE uses heated ethane to enable physical simulation of rocket engines powered by a broad range of propellants in an inexpensive, accurate, and simple fashion.

sub-scale↗

NASA NTRSDate not supplied

Pressure Fluctuations due to ‘Trapped Waves’ in Heated Jets

An experimental study was conducted to investigate the presence and characteristics of ‘trapped waves’ in the near field of a small axisymmetric jet at heated conditions. Trapped waves occur within the potential core of compressible jets and manifest as distinct peaks in the unsteady pressure spectra measured just outside the jet near the nozzle exit. The existence and properties of the trapped wave spectral peaks in round and rectangular jets of various sizes in subsonic and supersonic conditions were studied in our recent experiments, at cold conditions [7]. The current work extends the study to heated jets. Pressure fluctuation spectra near the nozzle exit are analyzed for a small (D = 6.35 mm) axisymmetric jet at stagnation temperature ratios up to 1.6. It is shown that trapped waves continue to persist in heated jets. At sufficiently high Mach numbers, one of the trapped wave harmonics emerges as screech tone, a behavior consistent with that observed in cold jets. For a given Mach number, the frequencies of both trapped waves and screech increase with jet temperature with no significant change occurring in their amplitudes. The Strouhal numbers based on jet diameter for the trapped waves and screech continue to follow similar scaling laws as observed previously with cold jets.

aeroacoustics↗

NASA NTRS2011

Sloshing of the Magnetized Cool Gas in the Cores of Galaxy Clusters

X-ray observations of many clusters of galaxies reveal the presence of edges in surface brightness and temperature, known as "cold fronts". In relaxed clusters with cool cores, these edges have been interpreted as evidence for the "sloshing" of the core gas in the cluster's gravitational potential. The smoothness of these edges has been interpreted as evidence for the stabilizing effect of magnetic fields "draped" around the front surfaces. To check this hypothesis, we perform high-resolution magnetohydrodynamics simulations of magnetized gas sloshing in galaxy clusters initiated by encounters with subclusters. We go beyond previous works on the simulation of cold fronts in a magnetized intracluster medium by simulating their formation in realistic, idealized mergers with high resolution ((Delta)x approx. 2 kpc). Our simulations sample a parameter space of plausible initial magnetic field strengths and field configurations. In the simulations, we observe strong velocity shears associated with the cold fronts amplifying the magnetic field along the cold front surfaces, increasing the magnetic field strength in these layers by up to an order of magnitude, and boosting the magnetic pressure up to near-equipartition with thermal pressure in some cases. In these layers, the magnetic field becomes strong enough to stabilize the cold fronts against Kelvin-Helmholtz instabilities, resulting in sharp, smooth fronts as those seen in observations of real clusters. These magnetic fields also result in strong suppression of mixing of high and low-entropy gas in the cluster, seen in our simulations of mergers in the absence of a magnetic field. As a result, the heating of the core due to sloshing is very modest and is unable to stave off a cooling catastrophe.

ZuHone, J. A.↗

NASA NTRS2000

Geoscience Laser Altimeter System (GLAS) Final Test Report of DM LHP TV Testing

Two loop heat pipes (LHPs) are to be used for thermal control of the Geoscience Laser Altimeter System (GLAS), planned for flight in 2001. One LHP will be used to transport 100 W from a laser to the radiator, the other will transport 210 W from electronic boxes to the radiator. In order to verify the LHP design for the GLAS application, an LHP Development Model has been fabricated, and ambient and thermal vacuum tested. Two aluminum blocks of 15 kg and 30 kg, respectively, were attached to the LHP to simulate the thermal masses connected to the heat sources. A 20 W starter heater was installed on the evaporator to aid the loop startup. A new concept to thermally couple the vapor and liquid line was also incorporated in the LHP design. Such a thermal coupling would reduce the power requirement on the compensation chamber in order to maintain the loop set point temperature. To avoid freezing of the liquid in the condenser during cold cases, propylene was selected as the working fluid. The LHP was tested under reflux mode and with adverse elevation. Tests conducted included start-up, power cycle, steady state and transient operation during hot and cold cases, and heater power requirements for the set point temperature control of the LHP. Test results showed very successful operation of the LHP under all conditions. The 20 W starter heater proved necessary in order to start the loop when a large thermal mass was attached to the evaporator. The thermal coupling between the liquid line and the vapor line significantly reduced the heater power required for loop temperature control, which was less than 5 watts in all cases, including a cold radiator. The test also demonstrated successful operation with a propylene working fluid, with successful startups with condenser temperatures as low as 100 C. Furthermore, the test demonstrated accurate control of the loop operating temperature within +/- 0.2 C, and a successful shutdown of the loop during the survival mode of operation.

Baker, Charles↗

NASA NTRS1973

Development of a high capacity variable conductance heat pipe.

The high-capacity, pressure-primed, tunnel-artery wick concept was used in a gas-controlled variable conductance heat pipe. A variety of techniques were employed to control the size of gas/vapor bubbles trapped within the artery. Successful operation was attained with a nominal 6-foot long, 1-inch diameter cold reservoir VCHP using ammonia working fluid and nitrogen control gas. The pipe contained a heat exchanger to subcool the liquid in the artery. Maximum transport capacity with a 46-inch effective length was 1200 watts level (more than 50,000 watt-inches) and 800 watts at 0.5-inch adverse tilt.

Kosson, R.↗

NASA NTRS1976

Bosch CO2 Reduction System Development

Development of a Bosch process CO2 reduction unit was continued, and, by means of hardware modifications, the performance was substantially improved. Benefits of the hardware upgrading were demonstrated by extensive unit operation and data acquisition in the laboratory. This work was accomplished on a cold seal configuration of the Bosch unit.

Holmes, R. F.↗