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At least 829 records · Page 46
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Utah FORGE 5-2428: Coupled Investigation of Fracture Permeability Impact on Reservoir Stress and Seismic Slip - 2024 Annual Workshop Presentation

This is a presentation on the Coupled Investigation of Fracture Permeability Impact on Reservoir Stress and Seismic Slip Behavior by Lawrence Livermore National Laboratory, presented by Kayla Kroll. This presentation addresses testing and modelling related to the dependency of EGS production on sustained permeability and sufficient fluid flow through pre-existing or induced fractures in hot rock. This presentation was featured in the Utah FORGE R&D Annual Workshop on August 13, 2024.

15 GEOTHERMAL ENERGY↗
DOE OSTI2023

Pressurized Water Reactor Gadolinia Pin Location Optimization

This report presents the results of lattice optimization studies performed to find optimum locations for gadolinia burnable absorber (BA) rods in pressurized water reactor (PWR) lattice fuel designs. Initial excess reactivity suppression allows core designers to further improve operational economics by extending cycle length. Gadolinia BAs are commonly used in boiling water reactor assembly designs for this purpose. In recent years, gadolinia absorbers have been used in PWR designs owing to their longer effectiveness for reactivity suppression compared with common BAs used in PWR assemblies. This report examines the optimum gadolinia pin placement in 17 × 17 PWR lattices at different fuel and gadolinia concentrations for optimized lattice performance, using the SCALE/Polaris lattice physics code. The completed work is continuation of the Light Water Reactor LEU+ Lattice Optimization (ORNL/TM-2021/2366) project. An optimization driver called the metaheuristic optimization tool (MOT) is used to automate domain space exploration and optimization of the lattice designs. Heuristics from previous light-water reactor (LWR) lattice optimization studies were used to construct the objective function and define the domain space for optimization. This work successfully demonstrated that the optimization algorithms of MOT can generate feasible, nonproprietary PWR lattice designs with gadolinia.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
NASA NTRS1974

Physics and potentials of fissioning plasmas for space power and propulsion

A brief description of two gas core reactor concepts devised for propulsion applications is presented and recent research on the emission of radiation from nonequilibrium fissioning gases is considered. The principles of UF6 and plasma core reactor experiments are discussed. It is expected that the program of nuclear gas core reactor experiments can lead in several years to reactor operation at pressures, temperatures, and power levels of technological significance to terrestrial applications.

Thom, K.↗
NASA NTRS1979

Static test-stand performance of the YF-102 turbofan engine with several exhaust configurations for the Quiet Short-Haul Research Aircraft (QSRA)

The performance of a YF-102 turbofan engine was measured in an outdoor test stand with a bellmouth inlet and seven exhaust-system configurations. The configurations consisted of three separate-flow systems of various fan and core nozzle sizes and four confluent-flow systems of various nozzle sizes and shapes. A computer program provided good estimates of the engine performance and of thrust at maximum rating for each exhaust configuration. The internal performance of two different-shaped core nozzles for confluent-flow configurations was determined to be satisfactory. Pressure and temperature surveys were made with a traversing probe in the exhaust-nozzle flow for some confluent-flow configurations. The survey data at the mixing plane, plus the measured flow rates, were used to calculate the static-pressure variation along the exhaust nozzle length. The computed pressures compared well with experimental wall static-pressure data. External-flow surveys were made, for some confluent-flow configurations, with a large fixed rake at various locations in the exhaust plume.

Mcardle, J. G.↗
NASA NTRS1982

Normal modes of a compound drop

The modes are characterized by their frequency, the attendant displacement of fluid boundaries, and the flow pressure fields within the fluids. The drops consist of three fluids; a core fluid, a fluid shell surrounding the core, and a host fluid surrounding the shell. These fluids are assumed to be inviscid and incompressible, and the core and the shell to be concentric. The theory is obtained by linearization of the equations of fluid motion to the lowest order of nonlinearity that yields the normal modes. Numerical values of mode frequencies and the associated relative displacements of the fluid boundaries are presented for several specific systems, and the results compared with observations.

Saffren, M.↗
NASA NTRS1984

Failure Analysis of Nickel-hydrogen Cell Subjected to Simulated Low Earth Orbit Cycling

A nickel-hydrogen cell completed 10,080 simulated low earth orbit charge/discharge cycles at depths-of-discharge ranging from 50 to 80 percent prior to failure. The cell is of the Air Force design, rated at 50 ampere-hours, 8.9 cm (3.5 inches) in diameter. Upon disassembly, the end of the polysulfone core supporting the electrode stack was found to have fractured. This allowed the electrode stack to expand. A massive short was found at the inner diameter of the electrodes centered roughly at plate set 34 to 37 from the positive end of the electrode stack. The damaged area extended through approximately one third of the electrode stack, with the effect becoming progressively less with distance from plate set 34 to 37. Measured thicknesses of the positive plates were significantly greater than the initial specification values. The postulated cause of failure is that positive plate growth caused fracture of the shoulder from the end of the polysulfone core on which the electrodes are mounted. The electrode stack relieved and pressure points were created at the area near the inner diameter of the plates at the tab attachment. A short occurred at a pressure point between opposing plates and propagated to other electrode sets due to thermal and mechanical stresses caused by the short.

Mueller, V. C.↗
NASA NTRS1985

Application of shock wave data to earth and planetary science

It is pointed out that shock wave data for: (1) low temperature condensable gases H2 and He, (2) H2O, CH4, NH3, CO, CO2, and N2 ices, and (3) silicates, metals, oxides and sulfides have many applications in geophysics and planetary science. The present paper is concerned with such applications. The composition of planetary interiors is discussed, taking into account the division of the major constituent of the planets in three groups on the basis of 'cosmic abundance' arguments, the H-He mixtures in the case of Jupiter and Saturn, shock wave data for hydrogen, and constraints on the internal structure of Uranus and Neptune. Attention is also given to the earth's mantle, shock wave data for mantle materials, the earth's core, impacts on planetary surfaces, elastic wave velocities as a function of pressure along the Hugoniot of iron, and reactions which yield the CO2 bearing atmospheres for Venus, earth, and Mars.

Ahrens, T. J.↗
NASA NTRS1989

The nature of cometary materials

Because cometary surfaces are likely to be far colder and of a different composition than planetary surfaces, there are some new considerations that must be examined in regards to placing instrumented packages or sample return devices on their surfaces. The qualitative analysis of the problem of attaching hardware to a comet and not being ejected back into space can be divided into two parts. The first problem is to pierce the mantle and obtain access to the icy core. Drilling through the mantle requires that the drilling forces be reacted. Reacting such forces probably requires attachment to the icy core below. Therefore, some kinetic impact piercing device is likely to be required as the first act of attachment. The second problem for a piercing device to overcome is the force produced by the impact kinetic energy that tries to eject the piercing device back into space. The mantle and icy core can absorb some of the impact kinetic energy in the form of fracture formation and friction energy. The energy that is not absorbed in these two ways is stored by the core as elastic deformation of the mantle and icy core. It is concluded that because the cometary materials are almost certainly brittle and the icy core is likely to be self lubricating, the elastic rebound and gas pressure expulsion forces must be counteracted by forces greater than those that may be provided by a piercing device or its capture devices (barbs).

Stephens, James↗
NASA NTRS1991

A parallel trajectory optimization tool for aerospace plane guidance

A parallel trajectory optimization algorithm is being developed. One possible mission is to provide real-time, on-line guidance for the National Aerospace Plane. The algorithm solves a discrete-time problem via the augmented Lagrangian nonlinear programming algorithm. The algorithm exploits the dynamic programming structure of the problem to achieve parallelism in calculating cost functions, gradients, constraints, Jacobians, Hessian approximations, search directions, and merit functions. Special additions to the augmented Lagrangian algorithm achieve robust convergence, achieve (almost) superlinear local convergence, and deal with constraint curvature efficiency. The algorithm can handle control and state inequality constraints such as angle-of-attack and dynamic pressure constraints. Portions of the algorithm have been tested. The nonlinear programming core algorithm performs well on a variety of static test problems and on an orbit transfer problem. The parallel search direction algorithm can reduce wall clock time by a factor of 10 for this part of the computation task.

Psiaki, Mark L.↗
NASA NTRS1987

Compound cycle engine for helicopter application

The compound cycle engine (CCE) is a highly turbocharged, power-compounded, ultra-high-power-density, lightweight diesel engine. The turbomachinery is similar to a moderate-pressure-ratio, free-power-turbine gas turbine engine and the diesel core is high speed and a low compression ratio. This engine is considered a potential candidate for future military helicopter applications. Cycle thermodynamic specific fuel consumption (SFC) and engine weight analyses performed to establish general engine operating parameters and configurations are presented. An extensive performance and weight analysis based on a typical 2-hour helicopter (+30 minute reserve) mission determined final conceptual engine design. With this mission, CCE performance was compared to that of a contemporary gas turbine engine. The CCE had a 31 percent lower-fuel consumption and resulted in a 16 percent reduction in engine plus fuel and fuel tank weight. Design SFC of the CCE is 0.33 lb/hp-hr and installed wet weight is 0.43 lb/hp. The major technology development areas required for the CCE are identified and briefly discussed.

Castor, Jere↗
NASA NTRS1993

Ureilite smelting

Ureilites containing homogeneous Fo76 olivine cores in intimate co-existence with graphite must have recrystallized at pressures of at least approximately 100 bars to suppress smelting of the fayalite component of the olivine to Fe metal. Smelting of olivine and pyroxene-saturated magmatic liquids produces orthopyroxene-without-olivine crystalline derivatives unlike those in ureilites. Thus the Mg# compositional variation within the ureilite suite, which is commonly attributed to partial smelting, cannot plausibly be produced by assemblages rich in liquid. In situ smelting of graphitic olivine + pigeonite crystal mushes can produce the correct crystal assemblage, but fails to provide a plausible account for the removal of metal from ureilites or for the correlation of Mg# with Delta O-17. Even if Mg# and Delta O-17 variations are established in the nebula, ureilite recrystallization with graphite must have occurred at pressures greater than the minima we have experimentally established, corresponding to parent objects not less than approximately 100 km in radius.

Walker, David↗
NASA NTRS1995

Effect of wake structure on blade-vortex interaction phenomena: Acoustic prediction and validation

During the Higher Harmonic Control Aeroacoustic Rotor Test, extensive measurements of the rotor aerodynamics, the far-field acoustics, the wake geometry, and the blade motion for powered, descent, flight conditions were made. These measurements have been used to validate and improve the prediction of blade-vortex interaction (BVI) noise. The improvements made to the BVI modeling after the evaluation of the test data are discussed. The effects of these improvements on the acoustic-pressure predictions are shown. These improvements include restructuring the wake, modifying the core size, incorporating the measured blade motion into the calculations, and attempting to improve the dynamic blade response. A comparison of four different implementations of the Ffowcs Williams and Hawkings equation is presented. A common set of aerodynamic input has been used for this comparison.

Gallman, Judith M.↗
NASA NTRS1995

An a priori model for the reduction of nutation observations: KSV(1994.3) nutation series

We discuss the formulation of a new nutation series to be used in the reduction of modern space geodetic data. The motivation for developing such a series is to develop a nutation series that has smaller short period errors than the IAU 1980 nutation series and to provide a series that can be used with techniques such as the Global Positioning System (GPS) that have sensitivity to nutations but can directly separate the effects of nutations from errors in the dynamical force models that effect the satellite orbits. A modern nutation series should allow the errors in the force models for GPS to be better understood. The series is constructed by convolving the Kinoshita and Souchay rigid Earth nutation series with an Earth response function whose parameters are partly based on geophysical models of the Earth and partly estimated from a long series (1979-1993) of very long baseline interferometry (VLBI) estimates of nutation angles. Secular rates of change of the nutation angles to represent corrections to the precession constant and a secular change of the obliquity of the ecliptic are included in the theory. Time dependent amplitudes of the Free Core Nutation (FCN) that is most likely excited by variations in atmospheric pressure are included when the geophysical parameters are estimated. The complex components of the prograde annual nutation are estimated simultaneously with the geophysical parameters because of the large contribution to the nutation from the S(sub 1) atmospheric tide. The weighted root mean square (WRMS) scatter of the nutation angle estimates about this new model are 0.32 mas and the largest correction to the series when the amplitudes of the ten largest nutations are estimated is 0.18 +/- 0.03 mas for the in phase component of the prograde 18. 6 year nutation.

Herring, T. A.↗
NASA NTRS1997

Crew Member Interface with Space Station Furnace Facility

The Space Station Furnace Facility (SSFF) is a facility located in the International Space Station United States Laboratory (ISS US Lab) for materials research in the microgravity environment. The SSFF will accommodate basic research, commercial applications, and studies of phenomena of metals and alloys, electronic and photonic materials, and glasses and ceramics. To support this broad base of research requirements, the SSFF will operate, regulate, and support a variety of Experiment Modules (EMs). To meet station requirements concerning the microgravity level needed for experiments, station is providing an active vibration isolation system, and SSFF provides the interface. SSFF physically consists of a Core Rack and two instrument racks (IRs) that occupy three adjacent ISS US Lab rack locations within the International Space Station (ISS). All SSFF racks are modified International Standard Payload Racks (ISPR). SSFF racks will have a 50% larger pass through area on the lower sides than ISPRs to accommodate the many rack to rack interconnections. The Instrument Racks are further modified with lowered floors and an additional removable panel (15" x 22") on top of the rack for access if needed. The Core Rack shall contain all centralized Core subsystems and ISS subsystem equipment. The two Instrument Racks shall contain the distributed Core subsystem equipment, ISS subsystem equipment, and the EMs. The Core System, which includes the Core Rack, the IR structures, and subsystem components located in the IRs serves as the central control and management for the IRs and the EMs. The Core System receives the resources provided by the International Space Station (ISS) and modifies, allocates, and distributes these resources to meet the operational requirements of the furnace. The Core System is able to support a total of four EMs and can control, support, and activate/deactivate the operations of two EMs, simultaneously. The IRs can be configured to house two small EMs or one tall vertical EM, and serve as the interface between the Core and the respective EM. The Core Rack and an adjacent Instrument Rack (containing one or more furnaces) will be delivered to the ISS in one launch. This is Integrated Configuration One (ICI). The Core Rack and IRI will be passive during transport in the Mini Pressurized Logistics Module (MPLM): Any subsequent EMs to operate within IRI are installed on-orbit. The second IR (containing one or more furnaces) is delivered to ISS on a subsequent launch which will establish Integrated Configuration Two (IC2). Additional integrated configurations will be established with the replacement of EMs or Instrument Racks.

Cash, Martha B.↗
NASA NTRS1994

The NASA Ames Closed Environmental Research Chamber: Present Status

The Closed Environmental Research Chamber (CERC) at the NASA Ames Research Center was created to investigate both components and complete systems for life support of advanced space exploration missions. This facility includes a Main Chamber, an Airlock, a Sample Transfer Lock, a Vacuum System, an Air Recompression System, a dedicated control room and a pit area for housing supporting and environmental control systems. The Main Chamber provides 310 sq ft of internal working/living space on two levels. It is planned that the CERC will be a human-rated facility for habitation simulation under mass balance closure conditions. The internal pressure will be variable over the range of 14.7 psia to 5 psia with accompanying capability for variation in atmosphere composition to maintain the oxygen partial pressure at 160 mm Hg. The CERC will be provided with a core set of primary life support subsystems for temperature and humidity control, C02 removal and trace contaminant control. Interfacing with external life support technology test b~ds with be provided, along with connection to centralized, microprocessor-based data acquisition and control systems. This paper will discuss the current status of the CERC facility and show how it is being used to address the advanced technology requirements necessary to implement an integrated working and living environment for a planetary habitat. In particular, it will be shown how the CERC, along with a human-powered centrifuge, a planetary terrain simulator and advanced displays and a virtual reality capability will work together to develop and demonstration applicable technologies for future planetary habitats. Artificial intelligence and expert system programming techniques will be used extensively to provide an automated environment for a 4-person crew. There will be several robotic mechanisms performing exploration tasks external to the habitat that will be controlled through the virtual environment to provide representative workloads for the crew. Finally, there will be a discussion of how effective are innovative new multidisciplinary test facilities to the investigation of the wide range of human and machine problems inherent in exploration missions.

Gross, Anthony R.↗
NASA NTRS2004

Mean Flow and Noise Prediction for a Separate Flow Jet With Chevron Mixers

Experimental and numerical results are presented here for a separate flow nozzle employing chevrons arranged in an alternating pattern on the core nozzle. Comparisons of these results demonstrate that the combination of the WIND/MGBK suite of codes can predict the noise reduction trends measured between separate flow jets with and without chevrons on the core nozzle. Mean flow predictions were validated against Particle Image Velocimetry (PIV), pressure, and temperature data, and noise predictions were validated against acoustic measurements recorded in the NASA Glenn Aeroacoustic Propulsion Lab. Comparisons are also made to results from the CRAFT code. The work presented here is part of an on-going assessment of the WIND/MGBK suite for use in designing the next generation of quiet nozzles for turbofan engines.

Koch, L. Danielle↗
NASA NTRS2005

NASA Tech Briefs, July 2005

Thin-Film Resistance Heat-Flux Sensors Circuit Indicates that Voice-Recording Disks are Nearly Full Optical Sensing of Combustion Instabilities in Gas Turbines Topics include: Crane-Load Contact Sensor; Hexagonal and Pentagonal Fractal Multiband Antennas; Multifunctional Logic Gate Controlled by Temperature; Multifunctional Logic Gate Controlled by Supply Voltage; Power Divider for Waveforms Rich in Harmonics; SCB Quantum Computers Using iSWAP and 1-Qubit Rotations; CSAM Metrology Software Tool; Update on Rover Sequencing and Visualization Program; Selecting Data from a Star Catalog; Rotating Desk for Collaboration by Two Computer Programmers; Variable-Pressure Washer; Magnetically Attached Multifunction Maintenance Rover; Improvements in Fabrication of Sand/Binder Cores for Casting; Solid Freeform Fabrication of Composite-Material Objects; Efficient Computational Model of Hysteresis; Gauges for Highly Precise Metrology of a Compound Mirror; Improved Electrolytic Hydrogen Peroxide Generator; High-Power Fiber Lasers Using Photonic Band Gap Materials; Ontology-Driven Information Integration; Quantifying Traversability of Terrain for a Mobile Robot; More About Arc-Welding Process for Making Carbon Nanotubes; Controlling Laser Spot Size in Outer Space; or Software-Reconfigurable Processors for Spacecraft.

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