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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 487 records · Page 27
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Ultra-High Vacuum Outgassing Characterization of Thermally Processed Low-Carbon Steel for Advanced Particle Accelerator and Gravitational Wave Detector Applications

This dissertation investigated AISI 1020 low-carbon steel as an alternative vacuum chamber material to conventional stainless steel for ultra-high vacuum (UHV) and extreme-high vacuum (XHV) applications. After a 400 °C/48 h bake, AISI 1020 tube chambers achieved a hydrogen outgassing rate of 2.4 × 10¿¹6 Torr·L·s¿¹·cm¿², approximately 2,300 times lower than the prebaked 316L stainless-steel comparator, among the lowest hydrogen outgassing rates ever reported for an uncoated metallic vacuum chamber. Bare and magnetite-coated AISI 1020 chambers were then compared using throughput and rate-of-rise methods. The magnetite coating yielded 5× lower water outgassing at room temperature, but this advantage disappeared after 80 °C baking. After full thermal conditioning (400 °C/48 h prebake followed by 150 °C/96 h and 200 °C/110 h), bare steel achieved 25× lower hydrogen outgassing than the magnetite-coated chamber (9.6 × 10¿¹6 Torr·L·s¿¹·cm¿²) and >99% H2 purity with carbon species below RGA detection. Monte Carlo molecular flow simulations of a CEBAF photogun beamline (96 scenarios) showed that replacing 304L stainless steel with AISI 1020 reduces equilibrium H2 pressure by a factor of 833; a single 304L electrode contributes 98.8% of the gas load despite occupying only 9.1% of the internal surface area. A 500-m Einstein Telescope beampipe screening showed that corrugated bellows contribute 18% of the gas load from only 0.7% of the surface area. A five-model adsorption isotherm framework applied to 22 pumpdown datasets (164 fits with AR(1)-GLS correction) established that the experimental protocol, not the material, controls isotherm identifiability: Dubinin–Radushkevich wins isothermal pipe pumpdowns; Langmuir wins thermally dominated chamber bakes. Cross-dataset joint fitting of the AISI 1020 pipe pumpdowns yielded an H2 diffusion activation energy Ed = 7.24 ± 1.28 kcal·mol¿¹, consistent with trap dominated diffusion in commercial low-carbon steels. Two companion innovations were developed: a Variable Conductance Device (VCD, patent pending IDF-00723) for XHV outgassing measurement, and VacuumDesignerPro (VDP), a MATLAB-based design tool validated against LIGO benchmarks.

Al-Allaq, Aiman H [Old Dominion University]↗
DOE OSTI2020

Ducted Fuel Injection versus Conventional Diesel Combustion: An Operating-Parameter Sensitivity Study Conducted in an Optical Engine with a Four-Orifice Fuel Injector

Ducted fuel injection (DFI) has been shown to attenuate engine-out soot emissions from diesel engines. The concept is to inject fuel through a small tube within the combustion chamber to enable lower equivalence ratios at the autoignition zone, relative to conventional diesel combustion. Previous experiments have demonstrated that DFI enables significant soot attenuation relative to conventional diesel combustion for a small set of operating conditions at relatively low engine loads. This is the first study to compare DFI to conventional diesel combustion over a wide range of operating conditions and at higher loads (up to 8.5 bar gross indicated mean effective pressure) with a four-orifice fuel injector. This study compares DFI to conventional diesel combustion through sweeps of intakeoxygen mole fraction (XO 2 ), injection duration, intake pressure, start of combustion (SOC) timing, fuel-injection pressure, and intake temperature. DFI is shown to curtail engine-out soot emissions at all tested conditions. Under certain conditions, DFI can attenuate engine-out soot by over a factor of 100. In addition to producing significantly lower engine-out soot emissions, DFI enables the engine to be operated at low-NO x conditions that are not feasible with conventional diesel combustion due to high soot emissions.

42 ENGINEERING↗
NASA NTRS1977

Two phase choke flow in tubes with very large L/D

Two phase and gaseous choked flow data for fluid nitrogen were obtained for a test section which was a long constant area duct of 16 200 L/D with a diverging diffuser attached to the exit. Flow rate data were taken along five isotherms (reduced temperature of 0.81, 0.96, 1.06, 1.12, and 2.34) for reduced pressures to 3. The flow rate data were mapped in the usual manner using stagnation conditions at the inlet mixing chamber upstream of the entrance length. The results are predictable by a two-phase homogeneous equilibrium choking flow model which includes wall fraction. A simplified theory which in essence decouples the long tube region from the high acceleration choking region also appears to predict the data reasonably well, but about 15 percent low.

Hendricks, R. C.↗
NASA NTRS1989

Laser/Plasma/Chemical-Vapor Deposition Of Diamond

Proposed process for deposition of diamond films includes combination of plasma induced in hydrocarbon feed gas by microwave radiation and irradiation of plasma and substrate by lasers. Deposition of graphite suppressed. Reaction chamber irradiated at wavelength favoring polymerization of CH2 radical into powders filtered out of gas. CH3 radicals, having desired sp3 configuration, remains in gas to serve as precursors for deposition. Feed gas selected to favor formation of CH3 radicals; candidates include CH4, C2H4, C2H2, and C2H6. Plasma produced by applying sufficient power at frequency of 2.45 GHz and adjusting density of gas to obtain electron kinetic energies around 100 eV in low-pressure, low-temperature regime.

Hsu, George C.↗
DOE OSTI2020

effect of ambient pressure on the behavior of single-component fuels in a gasoline multi-hole injector

The injection characteristics of neat ethanol and pure isooctane are studied under different ambient pressure and temperature conditions. Injection underflash-boiling conditions can enhance liquid atomization and evaporation, providing the possibility of improvement in the fuel/air mixing. These superheated conditions often introduce phenomena that are not taken into account in the standard modeling of sprays for engine applications. The present work proposes a numerical investigation of the behavior of Engine Combustion Network's 8-hole spray-G injector, starting at the subcooled nominal condition and reducing the ambient pressure at constant low temperature to reach the flare flash-boiling condition. To initialize the properties of the injected fuel, the flow in the nozzle is simulated with a Eulerian approach, handling the two phases with a mixture model and the phase change, due to cavitation and flash boiling, with the Homogenous Relaxation Model. A map of the mixture's kinematic and thermal behavior is obtained at the interface between the injector and the chamber to initialize the Lagrangian simulations. A literature-based vaporization model is implemented to obtain the proper description of the characteristic features of a multi-hole spray under super-heated conditions, like plume-plume interaction. The numerical representation of the spray is validated in terms of penetration and radial spreading on DBI images, reproducing the light attenuation profiles caused by the presence of the liquid spray. Simulations show that coupled nozzle flow and spray calculations capture the spray morphology and shape better compared to calculations performed without considering the nozzle flow simulation details, especially under flare flash conditions.

Nocivelli, Lorenzo↗
NASA NTRS1986

Dual-temperature acoustic levitation and sample transport apparatus

The properties of a dual-temperature resonant chamber to be used for acoustical levitation and positioning have been theoretically and experimentally studied. The predictions of a first-order dissipationless treatment of the generalized wave equation for an inhomogeneous medium are in close agreement with experimental results for the temperature dependence of the resonant mode spectrum and the acoustic pressure distribution, although the measured magnitude of the pressure variations does not correlate well with the calculated one. Ground-based levitation of low-density samples has been demonstrated at 800 C, where steady-state forces up to 700 dyn were generated.

Trinh, E.↗
NASA NTRS1991

Advanced development receiver thermal vacuum tests with cold wall

The first ever testing of a full size solar dynamic heat receiver using high temperature thermal energy storage was completed. The heat receiver was designed to meet the requirements for operation on the Space Station Freedom. The purpose of the test program was to quantify the receiver thermodynamic performance, its operating temperatures, and thermal response to changes in environmental and power module interface boundary conditions. The heat receiver was tested in a vacuum chamber with liquid nitrogen cold shrouds and an aperture cold plate to partially simulate a low Earth orbit environment. The cavity of the receiver was heated by an infrared quartz lamp heater with 30 independently controllable zones to produce flux distributions typical of candidate concentrators. A closed Brayton cycle engine simulator conditioned a helium xenon gas mixture to specific interface conditions to simulate various operational modes of the solar dynamic power module. Inlet gas temperature, pressure, and flow rate were independently varied. A total of 58 simulated orbital cycles were completed during the test conduct period. The test hardware, execution of testing, test data, and post test inspections are described.

Sedgwick, Leigh M.↗
NASA NTRS1991

Low thrust viscous nozzle flow field predictions

The low thrust viscous nozzle flows have been studied numerically by using the steady-state Reynolds-averaged Navier-Stokes equations in conservative form. A new Lower-Upper factorization scheme in the axisymmetric coordinate system has been developed and is analyzed in this paper. This new Navier-Stokes solver has shown that the numerical analog is accurate and stable for the convergent and divergent nozzle flowfield calculation. The range of the chamber pressure is (1.85-29.4)psi with the chamber temperature equal to 600 F. The results are compared with the data collected in the NASA/MSFC vacuum chamber, and they are in very reasonable agreement.

Chou, L. C.↗
NASA NTRS1992

Development of generalized pressure velocity coupling scheme for the analysis of compressible and incompressible combusting flows

The objective of this investigation has been to develop an algorithm (or algorithms) for the improvement of the accuracy and efficiency of the computer fluid dynamics (CFD) models to study the fundamental physics of combustion chamber flows, which are necessary ultimately for the design of propulsion systems such as SSME and STME. During this three year study (May 19, 1978 - May 18, 1992), a unique algorithm was developed for all speed flows. This newly developed algorithm basically consists of two pressure-based algorithms (i.e. PISOC and MFICE). This PISOC is a non-iterative scheme and the FICE is an iterative scheme where PISOC has the characteristic advantages on low and high speed flows and the modified FICE has shown its efficiency and accuracy to compute the flows in the transonic region. A new algorithm is born from a combination of these two algorithms. This newly developed algorithm has general application in both time-accurate and steady state flows, and also was tested extensively for various flow conditions, such as turbulent flows, chemically reacting flows, and multiphase flows.

Chen, C. P.↗
NASA NTRS1991

Energy deposition in low-power coaxial plasma thrusters

An experimental examination of energy deposition in self-field, coaxial plasma thrusters revealed that the thrust efficiency ranged from 2-9 percent and that the dominant losses resulted from electrode heating and propellant ionization. Sensible enthalpy and radiative losses were negligible. Thruster specific impulse increased with current, ranging from 550-1750 seconds. Spectroscopic studies of the plume plasma showed that the electron temperature ranged from 0.5-2.5 eV and that the dominant species were singly and doubly ionized argon. Attempts to raise thruster efficiency by increasing the chamber pressure resulted in reduced electrode losses and lowered I(sp), but the thrust efficiency decreased because of a current redistribution that lowered the thrust beyond expectations.

Myers, R. M.↗
NASA NTRS1987

Petrology of gabbroic rocks from the Mid-Cayman rise spreading center

Mineral analyses of oxide and silicate phases from a suite (collected with the DSRV Alvin in January 1976 and July 1977) of 48 gabbroic rocks collected from the vicinity of the Mid-Cayman Rise spreading center are reported. Mineral compositions of these anorthosites, leuco-troctolite, leuco-olivine gabbros, olivine gabbros, leuco-gabbros, and gabbros indicate the cumulate rocks have been produced by the crystal fractionation of basaltic liquids. Certain features of these rocks are inconsistent with the occurrence of this fractionation at low pressures (1 atm to 2 kbar). Although the experimental data are not available to conclusively demonstrate that the effects seen were produced at moderate pressures (5-10 kbar), the effects are similar to those predicted thermodynamically and to those observed in limited experimental studies within this pressure range. It is therefore suggested that the most likely scenario for the production of these gabbroic rocks is the moderate-pressure crystallization of basaltic magmas within deep-seated magma chambers underneath this slow-spreading center.

Elthon, Don↗
NASA NTRS1950

Altitude-chamber performance of British Rolls-Royce Nene II engine III : 18.00-inch-diameter jet nozzle

An altitude-chamber investigation of British Rolls-Royce Nene II turbojet engine was conducted over range of altitudes from sea level to 65,000 feet and ram pressure ratios from 1.10 to 3.50, using an 18.00-inch-diameter jet nozzle. The 18.00-inch-diameter jet nozzle gave slightly lower values of net-thrust specific fuel consumption than either the 18.41- or the standard 18.75-inch-diameter jet nozzles at high flight speeds. At low flight speeds, the 18.41-inch-diameter jet nozzle gave the lowest value of net-thrust specific fuel consumption.

ENGINES, TURBOJET↗
NASA NTRS1973

Low frost-point humidity generator

A low frost-point humidity generator has been developed at NBS to provide a capability for calibration, testing, and research at very low levels of water vapor content in such gases as atmospheric air, carbon dioxide and nitrogen. The generator produces frost points from -30 to -100 C at ambient pressures from 500 to 200,000 pascals (0.005 to 2 atm.). This is equivalent to mixing ratios of 4 micrograms to 51 grams of water vapor per kilogram of dry air and to vapor pressures of .0014 to 38 pascals. The generated test gas can be fed to a test chamber with independent temperature control between +25 and -100 C. The uncertainty of the frost point in the test chamber is estimated not to exceed 0.05 deg C.

Greenspan, L.↗
NASA NTRS1988

Normal incidence reflectance of ion beam deposited SiC films in the EUV

Results are presented from an experimental investigation of the normal-incidence reflectance at 58.4, 92.0, and 121.6 nm wavelength of 30- and 80-nm-thick SiC films produced by ion-beam deposition on unheated 5 x 5-cm microscope slides. The films were deposited in the 2-m evaporator described by Bradford et al. (1969) with chamber base pressure 1 microtorr, operating pressure 40 microtorr, and a 50-62-mA 750-eV Ar ion beam; the reflectance measurements were obtained in the reflector-monochromator system described by Osantowski (1974). Reflectances of over 30 percent were found at 92 and 121.6 nm, almost equal to those of polished CVD films of SiC and degrading only slightly after aging for 4 months. It is suggested that ion-beam deposition may be the best low-temperature technique for coating EUV optics for space astronomy.

Keski-Kuha, Ritva A. M.↗
NASA NTRS1996

Pressure Oscillations in Shuttle Solid Rocket Motors

All Shuttle Solid Rocket Motors (SRM's) exhibit low amplitude longitudinal pressure oscillations during motor burn. Although the oscillations have no known deleterious effect on motor ballistics, the acoustic pressure variations cause thrust oscillations that might affect Shuttle systems or components. The acoustic mode of greatest interest is the first or fundamental mode which, in the SRM, has a nominal frequency of 14-Hz. Oscillations in the SRM are believed to be caused by coupling between large scale vortices and the acoustic modes of the motor chamber. The vortices are thought to be created in the region of the motor segment interfaces and are inherent in the design of the motor. In such a situation the usual approach is to measure the oscillations and assess their impact on any sensitive components through tests and analysis. Questionable components can be altered to survive the vibration environment. As motor firings occur, oscillations are monitored to determine whether there are changes in the nature of the oscillations. Since the first static test, SRM's have been equipped with instrumentation especially designed to acquire chamber pressure oscillation data. Data from the first SRM static tests were used to establish predicted upper bounds for the maximum amplitudes in the latter half of burn. Those bounds have been used as a basis for worst-case simulation scenarios by specialists in structural dynamics at NASA and Rockwell International and to provide a basis for evaluating data from individual motors which were tested subsequent to the original SRM's. This paper updates the upper bounds prediction the High Performance Motors (HPM) by including data from all static tests performed to date including both original SRM's and post Challenger SRM's or Reusable Solid Rocket Motors (RSRM) in which the joint design was changed. All together, this study examines 27 SRM motors, 16 HPM motors and 11 RSRM motors. Predicted upper bounds will be made for both the first and second longitudinal modes. The first mode upper bounds will be compared to the original seven standard rocket motors (STD). The results indicate that, although the upper bounds have increased, they are still within acceptable bounds.

Blomshield, Fred S.↗
NASA NTRS1960

An Experimental Investigation of Boundary-Layer Control for Drag Reduction of a Swept-Wing Section at Low Speed and High Reynolds Numbers

An investigation of laminar boundary-layer control by suction for purposes of drag reduction at low speed and high Reynolds numbers has been conducted in the Ames 12-Foot Pressure Wind Tunnel. The model was a 72.96-inch-chord wing panel, swept back 30 deg., which was installed between end plates to approximate a wing of infinite span. The airfoil section employed was a modified NACA 66-012 in the streamwise direction. Tests were limited to controlling the flow over only the upper surface of the model. Seventeen individually controllable suction chambers were provided below the surface to induce flow through 93 spanwise slots in the surface between the 0.0052- and 0.97-chord stations. Tests were made at angles of attack of 0 deg., +/- 1.0 deg., +/- 1.5 deg., and -2.0 deg. for Reynolds numbers from approximately 1.5 x 10(exp 6) to 4.0 x 10(exp 6) per foot. In general, essentially full-chord laminar flow was obtained for all conditions with small suction quantities. Minimum profile-drag coefficients of about 0.0005 to 0.0006 were obtained for the slotted surface at maximum values of the Reynolds number; these values include the Power required to induce suction as an equivalent drag.

Gault, Donald E.↗
NASA NTRS2023

Commercial Low-Earth Orbit Destination (CLD) Capabilities of Interest and Resource Needs

The Commercial Low Earth Orbit (LEO) Development Program team has been working with NASA and the International Space Station (ISS) National Lab (NL) stakeholders to identify capabilities of interest to both conduct research/technology demonstrations and estimate the resources that will be needed from Commercial LEO Destinations (CLDs). Through a series of one-on-one and working group meetings with users/stakeholders, hardware items of interest to the user community were identified and converted into capabilities (e.g., centrifugation, microscope, pressure chamber, etc.). In parallel, resources needed to operate the research equipment (e.g., crew time, number of experiments, volume, etc.) were estimated in order for the CLD providers to better understand NASA’s potential future service requirements. The capabilities and the resources included in this White Paper do not represent NASA requirements. Instead, they constitute a preliminary set of potential capability and resource needs collated to guide CLD providers in appropriately sizing and outfitting their CLD designs. NASA is requesting feedback from industry on how these capabilities and resources align with their own needs as well as those of their non-NASA customers. Information on how the capabilities/resources impact the CLD designs is also requested. After assessing industry’s feedback to this white paper, NASA plans to issue a preliminary set of requirements for review.

International Space Station↗
DOE OSTI2025

High Pressure DME-Driven Fractional Crystallizations

Rare Earth Elements (REEs), include the 15 lanthanides plus yttrium and scandium and are crucial for various technologies and applications. Their low concentrations in the earth's crust require alternative sources. This study explores antisolvent fractional crystallization (FC) using dimethyl ether (DME) under high pressures to extract REEs from secondary sources such as mining waste, coal byproducts, and e-waste. DME's properties, including its solubility in water, small molecular size, and high vapor pressure, make it an effective antisolvent that can be easily recovered and reused. The method involves pressurizing DME to 1000-2000 psi in a reaction chamber with the test solution, followed by sample collection and analysis using ICP-MS and ICP-OES. This approach aims to address the limitations of current extraction methods, such as high energy consumption, chemical usage, and waste production, offering a potentially more efficient and sustainable solution for REE extraction.

37 - INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL C↗