Bearings and seals for cryogenic fluids
Lubricating mechanism, cage design, and heat generation of ball bearings for liquid hydrogen turbopumps, and design factors of contact seals for liquid fluorine pumps
Scibbe, H. W.↗
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Natural Frequency Testing and Model Correlation of Rocket Engine Structures in Liquid Hydrogen - Phase I, Cantilever Beam
Many structures in the launch vehicle industry operate in liquid hydrogen (LH2), from the hydrogen fuel tanks through the ducts and valves and into the pump sides of the turbopumps. Calculating the structural dynamic response of these structures is critical for successful qualification of this hardware, but accurate knowledge of the natural frequencies is based entirely on numerical or analytical predictions of frequency reduction due to the added-fluid-mass effect because testing in LH2 has always been considered too difficult and dangerous. This fluid effect is predicted to be approximately 4-5% using analytical formulations for simple cantilever beams. As part of a comprehensive test/analysis program to more accurately assess pump inducers operating in LH2, a series of frequency tests in LH2 were performed at NASA/Marshall Space Flight Center's unique cryogenic test facility. These frequency tests are coupled with modal tests in air and water to provide critical information not only on the mass effect of LH2, but also the cryogenic temperature effect on Young's Modulus for which the data is not extensive. The authors are unaware of any other reported natural frequency testing in this media. In addition to the inducer, a simple cantilever beam was also tested in the tank to provide a more easily modeled geometry as well as one that has an analytical solution for the mass effect. This data will prove critical for accurate structural dynamic analysis of these structures, which operate in a highly-dynamic environment.
Brown, Andrew M.↗
Crowd-Sourced Technology Challenge for Improving Visual Color Detection of Hydrazine and Monomethylhydrazine Vapors in Spacecraft Environments
NASA currently uses a visual colorimetric detection method for potential hydrazine, monomethylhydrazine (MMH), or unsymmetrical dimethylhydrazine (UDMH) contamination in the International Space Station. Astronauts exposed to propellants or their residues during extravehicular activities may transfer contaminants into the airlock. The colorimetric detection method employs the Contamination Detection Kit (CDK), which uses a potassium tetrachloroaurate redox reaction with the propellant hydrazine vapors and a color comparison card to determine airborne concentrations. Seeking ideas for improvement, the NASA Tournament Lab (NTL) crowdsourced a way to tackle the challenge of detecting hydrazine and MMH vapors using colorimetric detection methods. This Rid the Rocket competition drew over 200 participants and 20 submissions from around the world proposing innovative ways to develop a new chemical colorimetric detection method for hydrazine and MMH vapors on spacecraft. Using a phased approach to evaluate contestants, NASA eventually narrowed the field to five finalists from the United States, Romania, Taiwan, and India. Concept papers and hardware submissions were judged on feasibility, creativity, and ability to detect hydrazine and MMH vapors before being sent to the NASA White Sands Test Facility for laboratory evaluation. Finalists employed variations of sampling methods and color-detection chemistry using a variety of sampling pumps and indicator pads or solutions—including those employing potassium or hydrogen tetrachloroaurate, para -dimethylaminobenzaldehyde (PDAB), and modifiers including sodium metasilicate and cetyltrimethylammonium bromide—to enhance gold nanoparticle formation and surface plasmon resonance (SPR) resulting in visual blue to purple color development. This paper presents a summary of the crowdsourced submissions and results of laboratory testing.
Crowd-Sourced↗
Fiber optic Raman thermometer for Space Shuttle main engine preburner profiling
The feasibility of combustion gas temperature measurements in the SSME fuel preburner using nonintrusive optical diagnostics was investigated. Temperature profiles are desired in the high pressure, hydrogen-rich preburner stream to evaluate designs to alleviate thermal stressing of the fuel pump turbine blades. Considering the preburner operating conditions and optical access restrictions, a spontaneous Raman backscattering system, implemented with optical fibers to couple to the combustion device, was selected as the most practical for gas temperature probing. A system is described which employs a remotely-located argon-ion laser to excite the molecular hydrogen Raman spectrum. The laser radiation is conveyed to the combustor through an optical fiber and focused through a window into the chamber by an optical head attached to the combustor. The gas temperature is determined from the distribution of rotational populations represented in the Raman spectrum.
Shirley, J. A.↗
NASA's Hydrogen Outpost: The Rocket Systems Area at Plum Brook Station
"There was pretty much a general knowledge about hydrogen and its capabilities," recalled former researcher Robert Graham. "The question was, could you use it in a rocket engine? Do we have the technology to handle it? How will it cool? Will it produce so much heat release that we can't cool the engine? These were the questions that we had to address." The National Aeronautics and Space Administration's (NASA) Glenn Research Center, referred to historically as the Lewis Research Center, made a concerted effort to answer these and related questions in the 1950s and 1960s. The center played a critical role transforming hydrogen's theoretical potential into a flight-ready propellant. Since then NASA has utilized liquid hydrogen to send humans and robots to the Moon, propel dozens of spacecraft across the universe, orbit scores of satellite systems, and power 135 space shuttle flights. Rocket pioneers had recognized hydrogen's potential early on, but its extremely low boiling temperature and low density made it impracticable as a fuel. The Lewis laboratory first demonstrated that liquid hydrogen could be safely utilized in rocket and aircraft propulsion systems, then perfected techniques to store, pump, and cleanly burn the fuel, as well as use it to cool the engine. The Rocket Systems Area at Lewis's remote testing area, Plum Brook Station, played a little known, but important role in the center's hydrogen research efforts. This publication focuses on the activities at the Rocket Systems Area, but it also discusses hydrogen's role in NASA's space program and Lewis's overall hydrogen work. The Rocket Systems Area included nine physically modest test sites and three test stands dedicated to liquid-hydrogen-related research. In 1962 Cleveland Plain Dealer reporter Karl Abram claimed, "The rocket facility looks more like a petroleum refinery. Its test rigs sprout pipes, valves and tanks. During the night test runs, excess hydrogen is burned from special stacks in the best Oklahoma oil field tradition." Besides the Rocket Systems Area, Plum Brook Station also included a nuclear test reactor, a large vacuum tank, a hypersonic wind tunnel, and a full-scale upper-stage rocket stand. The Rocket Systems Area operated from 1961 until NASA shut down all of Plum Brook in 1974. The center reopened Plum Brook in the late 1980s and continues to use several test facilities. The Rocket Systems Area, however, was not restored. Today Plum Brook resembles a nature preserve more than an oil refinery. Lush fields and forests separate the large test facilities. Until recently, the abandoned Rocket Systems Area structures and equipment were visible amongst the greenery. These space-age ruins, particularly the three towers, stood as silent sentinels over the sparsely populated reservation. Few knew the story of these mysterious facilities when NASA removed them in the late 2000s.
Rocket Systems↗
NASA Technology Evaluation for Environmental Risk Mitigation Remediation Technology Collaboration Development
NASA is committed to finding solutions to agency cleanup problems that are better, cheaper, and more effective than the status quo. Unfortunately, some potential solutions involve innovative technologies for which NASA remediation managers may not have a high level of understanding or confidence. Since 2004, NASA's Stennis Space Center (SSC) in Mississippi has been pumping groundwater contaminated with trichloroethylene (TCE) and other halogenated volatile organic compounds (HVOC) from their cleanup location designated "Area G" through extraction wells to an aboveground treatment system. Over time, however, the effectiveness of this treatment strategy has diminished and an alternative approach is needed. In 2012, professionals from NASA's Principal Center for Technology Evaluation for Environmental Risk Mitigation (TEERM) introduced SSC managers to an innovative technology for enhancing the performance of SSC's existing pump and treat system. The technology, generally referred to as in situ chemical oxidation (ISCO), involves slowly and continuously injecting a strong but safe chemical oxidant into the groundwater. Treatment is enhanced by a "surfactant-type effect" which causes residual contamination from saturated soil to be released into the dissolved-phase where it can be readily oxidized. Any dissolved-phase contamination that was not oxidized can be collected by the extraction well network and treated aboveground. SSC was not familiar with the technology so to increase their confidence, TEERM identified a contractor who was willing to demonstrate their product and process at a significantly reduced price. An initial, small-scale demonstration of ISCO began at sse in March 2012 and completed in August 2012. This successful demonstration was followed by three larger-scale ISCO demonstrations between August and December 2012. The contractor's innovative Continuous Injection System (CIS) incorporated "green" and sustainable technologies and practices. A slow injection rate was maintained autonomously by the CIS, eliminating the need for multiple mobilizations of personnel and powered equipment. The CIS was calibrated to deliver only as much reagent as the formation would accept without "short circuiting", minimizing material waste. Public utility water pressure was used to mix, dilute, and inject the reagent. NASA personnel were trained to operate and maintain the system and remote monitoring and injection control capabilities were developed, further reducing the need for contractor mobilizations to the site. An integrated solar photovoltaic panel was used to power the control valves and web monitoring telemetry. SSC provided hydrogen peroxide for the process using their existing supplier for the aboveground pump and treat systems. The only consumable required from the contractor was their proprietary activator to catalyze SSC's peroxide.
Romeo, James↗
Experiments on the interaction of Lyman alpha radiation and atomic hydrogen.
Hydrogen atom excitation by Lyman alpha radiation absorption in electric field
HYDROGEN ATOM↗
Replication of the Apparent Excess Heat Effect in a Light Water-Potassium Carbonate-Nickel Electrolytic Cell
Replication of experiments claiming to demonstrate excess heat production in light water-Ni-K2CO3 electrolytic cells was found to produce an apparent excess heat of 11 W maximum, for 60 W electrical power into the cell. Power gains range from 1.06 to 1.68. The cell was operated at four different dc current levels plus one pulsed current run at 1 Hz, 10% duty cycle. The 28 liter cell used in these verification tests was on loan from a private corporation whose own tests with similar cells are documented to produce 50 W steady excess heat for a continuous period exceeding hundreds of days. The apparent excess heat can not be readily explained either in terms of nonlinearity of the cell's thermal conductance at a low temperature differential or by thermoelectric heat pumping. However, the present data do admit efficient recombination of dissolved hydrogen-oxygen as an ordinary explanation. Calorimetry methods and heat balance calculations for the verification tests are described. Considering the large magnitude of benefit if this effect is found to be a genuine new energy source, a more thorough investigation of evolved heat in the nickel-hydrogen system in both electrolytic and gaseous loading cells remains warranted.
Niedra, Janis M.↗
Computing Thermal Effects of Cavitation in Cryogenic Liquids
A computer program implements a numerical model of thermal effects of cavitation in cryogenic fluids. The model and program were developed for use in designing and predicting the performances of turbopumps for cryogenic fluids. Prior numerical models used for this purpose do not account for either the variability of properties of cryogenic fluids or the thermal effects (especially, evaporative cooling) involved in cavitation. It is important to account for both because in a cryogenic fluid, the thermal effects of cavitation are substantial, and the cavitation characteristics are altered by coupling between the variable fluid properties and the phase changes involved in cavitation. The present model accounts for both thermal effects and variability of properties by incorporating a generalized representation of the properties of cryogenic fluids into a generalized compressible-fluid formulation for a cavitating pump. The model has been extensively validated for liquid nitrogen and liquid hydrogen. Using the available data on the properties of these fluids, the model has been shown to predict accurate temperature-depression values.
Hosangadi, Ashvin↗
Ionization-Assisted Getter Pumping for Ultra-Stable Trapped Ion Frequency Standards
A method eliminates (or recovers from) residual methane buildup in getter-pumped atomic frequency standard systems by applying ionizing assistance. Ultra-high stability trapped ion frequency standards for applications requiring very high reliability, and/or low power and mass (both for ground-based and space-based platforms) benefit from using sealed vacuum systems. These systems require careful material selection and system processing (cleaning and high-temperature bake-out). Even under the most careful preparation, residual hydrogen outgassing from vacuum chamber walls typically limits the base pressure. Non-evaporable getter pumps (NEGs) provide a convenient pumping option for sealed systems because of low mass and volume, and no power once activated. An ion gauge in conjunction with a NEG can be used to provide a low mass, low-power method for avoiding the deleterious effects of methane buildup in high-performance frequency standard vacuum systems.
Tjoelker, Robert L.↗
Effect of hydrogen bonding on the vibrational dephasing time in glycerol
The vibrational dephasing of the methyl CH2 symmetric stretch mode in glycerol was directly measured over an extended temperature range using picosecond coherent Raman pump and probe spectroscopy. The dephasing time was found to increase dramatically as the temperature of the supercooled liquid was lowered. This observation is attributed to the increased hydrogen bonding with decreasing temperature which hinders the dephasing of the CH2 vibration by reducing molecular motions.
Dorsinville, R.↗
Hydrogen Peroxide Concentrator
A relatively simple and economical process and apparatus for concentrating hydrogen peroxide from aqueous solution at the point of use have been invented. The heart of the apparatus is a vessel comprising an outer shell containing tubular membranes made of a polymer that is significantly more permeable by water than by hydrogen peroxide. The aqueous solution of hydrogen peroxide to be concentrated is fed through the interstitial spaces between the tubular membranes. An initially dry sweep gas is pumped through the interiors of the tubular membranes. Water diffuses through the membranes and is carried away as water vapor mixed into the sweep gas. Because of the removal of water, the hydrogen peroxide solution flowing from the vessel at the outlet end is more concentrated than that fed into the vessel at the inlet end. The sweep gas can be air, nitrogen, or any other gas that can be conveniently supplied in dry form and does not react chemically with hydrogen peroxide.
Parrish, Clyde F.↗
Fission fragment assisted reactor concept for space propulsion: Foil reactor
The concept is to fabricate a reactor using thin films or foils of uranium, uranium oxide and then to coat them on substrates. These coatings would be made so thin as to allow the escaping fission fragments to directly heat a hydrogen propellant. The idea was studied of direct gas heating and direct gas pumping in a nuclear pumped laser program. Fission fragments were used to pump lasers. In this concept two substrates are placed opposite each other. The internal faces are coated with thin foil of uranium oxide. A few of the advantages of this technology are listed. In general, however, it is felt that if one look at all solid core nuclear thermal rockets or nuclear thermal propulsion methods, one is going to find that they all pretty much look the same. It is felt that this reactor has higher potential reliability. It has low structural operating temperatures, very short burn times, with graceful failure modes, and it has reduced potential for energetic accidents. Going to a design like this would take the NTP community part way to some of the very advanced engine designs, such as the gas core reactor, but with reduced risk because of the much lower temperatures.
Wright, Steven A.↗
A comparison of cooling methods for the airframe nozzle of a single-stage-to-orbit aircraft
A comparison is made between two different cooling schemes, including a complete system thermal analysis and weight accounting for each. A hydrogen-direct system operates at a higher pressure (34.5 Mpa) and greater temperature rise in the coolant. There is no temperature limit on the coolant itself and high injector temperatures may be achieved, but the pressure lines must be routed over great distances (10 m). The system is simple, and the coolant is almost weightless. In contrast, an indirect system operates at a lower pressure (3.8n MPa) and the liquid coolant has a much greater thermal capacity. The greater thermal capacity causes much less of a temperature rise in the coolant. The chosen coolant is Syltherm 800. This nontoxic fluid is compatible with any metal, including titanium. The loop requires a separate fuel/coolant heat exchanger and coolant pump. The indirect system offers some distinct safety advantages but is heavier than the direct hydrogen coolant system.
Jones, Stuart C.↗
Buffer Gas Experiments in Mercury (Hg+) Ion Clock
We describe the results of the frequency shifts measured from various buffer gases that might be used as a buffer gas to increase the loading efficiency and cooling of ions trapped in a small mercury ion clock. The small mass, volume and power requirement of space clock precludes the use of turbo pumps. Hence, a hermetically sealed vacuum system, incorporating a suitable getter material with a fixed amount of inert buffer gas may be a practical alternative to the groundbased system. The collision shifts of 40,507,347.996xx Hz clock transition for helium, neon and argon buffer gases were measured in the ambient earth magnetic field. In addition to the above non-getterable inert gases we also measured the frequency shifts due to getterable, molecular hydrogen and nitrogen gases which may be used as buffer gases when incorporated with a miniature ion pump. We also examined the frequency shift due to the low methane gas partial pressure in a fixed higher pressure neon buffer gas environment. Methane gas interacted with mercury ions in a peculiar way as to preserve the ion number but to relax the population difference in the two hyperfine clock states and thereby reducing the clock resonance signal. The same population relaxation was also observed for other molecular buffer gases (N H ,) but at much reduced rate.
mercury ion clock↗
Dual-Pump CARS Measurements in the University of Virginia's Dual-Mode Scramjet: Configuration "C"
Measurements have been conducted at the University of Virginia Supersonic Combustion Facility in configuration C of the dual-mode scramjet. This is a continuation of previously published works on configuration A. The scramjet is hydrogen fueled and operated at two equivalence ratios, one representative of the scram mode and the other of the ram mode. Dual-pump CARS was used to acquire the mole fractions of the major species as well as the rotational and vibrational temperatures of N2. Developments in methods and uncertainties in fitting CARS spectra for vibrational temperature are discussed. Mean quantities and the standard deviation of the turbulent fluctuations at multiple planes in the flow path are presented. In the scram case the combustion of fuel is completed before the end of the measurement domain, while for the ram case the measurement domain extends into the region where the flow is accelerating and combustion is almost completed. Higher vibrational than rotational temperature is observed in those parts of the hot combustion plume where there is substantial H2 (and hence chemical reaction) present.
Cutler, Andrew D.↗
Hydrogen Densification for Nuclear Thermal Propulsion Missions
Propellant densification is cooling the propellant below the normal boiling point; Densified propellants can either be saturated or subcooled. Propellant densification has two potential benefits; Increased density for more mass in a given volume (more propellant), Decrease temperature for thermal energy buffer (extended storage). Two primary methods for producing densified propellants; Vapor pumping for pressure control, Refrigeration for temperature control. SpaceX has been flying densified liquid oxygen for several years. NASA has developed and tested hydrogen densification systems but have never been used in an operational mission
densified propellants↗
Performance of the new Efratom optically pumped rubidium frequency standards and their possible application in space relativity experiments
The characteristics of Efratom optically pumped rubidium frequency standards are discussed. The Efratom units were compared with cesium beam and hydrogen maser standards and showed a stability of approximately 5 times 10 to the minus 12th power over two one-week periods. Dependency of frequency upon the environmental parameters of pressure, magnetic field, temperature, supply voltage, and acceleration was measured. A package of three units with automatic phase comparison and recording was designed and constructed to allow a measurement of relativistic effects on time with high accuracy during space missions.
Alley, C. O.↗