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NASA NTRS1976

Observations of Mercury's magnetic field

Magnetic-field observations made during the third encounter of Mariner 10 with Mercury are discussed along with implications of an intrinsic field for the planetary interior. The data obtained confirm the presence of characteristic bow-shock, magnetosheath, and magnetosphere regions surrounding the planet and also indicate that Mercury occupies a much larger portion of its magnetosphere than does earth. Combined plasma, charged-particle, and magnetic-field data establish that the origin of the field is intrinsic to the planet rather than associated with an induction process due to solar-wind flow. Spherical harmonic analysis of the field data shows that the internal field of the planet is well described by a centered dipole with a moment of 5.0 by 10 to the 22nd power gauss-cu cm and oriented within 12 deg of the normal to the orbital plane in the same sense as earth. Surface intensities are deduced to be between about 300 and 800 gammas. It is concluded that an active dynamo is a more likely candidate than fossil magnetization for the origin of the field.

Ness, N. F.↗

NASA NTRS1991

Solar control of the earth's emission of energetic O(+)

Energetic (0.1-16 keV/e) O(+) data obtained in the earth's plasma sheet (between 10 and 23 RE) by an ion mass spectrometer on the ISEE-1 spacecraft are compared statistically with published data on the concurrent solar wind and IMF. The most strongly variable parameter of the plasma sheet O(+) is its density, which is found to be well correlated with certain solar wind parameters, especially with the solar wind flow speed and the IMF component perpendicular to the flow vector. When those two solar wind parameters are combined to form an electric field (-v x B), both the number density and the energy density of the O(+) are found to vary in proportion to the square of that electric field, on average, suggesting that the emission of energetic O(+) ions from the earth may be powered by that same field. Based on this and on the previously published correlation with solar activity, it is argued that the emission of O(+) is controlled by a combination of HF (ionizing) and quasi-static (accelerating) solar electromagnetic fields.

Lennartsson, W.↗

NASA NTRS2010

Development of a Fan for Future Space Suit Applications

NASA's next generation space suit system will place new demands on the fan used to circulate breathing gas through the ventilation loop of the portable life support system. Long duration missions with frequent extravehicular activities (EVAs), the requirement for significant increases in reliability and durability, and a mission profile that imposes strict limits on weight, volume and power create the basis for a set of requirements that demand more performance than is available from existing fan designs. This paper describes the development of a new fan to meet these needs. A centrifugal fan was designed with a normal operating speed of approximately 39,400 rpm to meet the ventilation flow requirements while also meeting the aggressive minimal packaging, weight and power requirements. The prototype fan also operates at 56,000 rpm to satisfy a second operating condition associated with a single fan providing ventilation flow to two spacesuits connected in series. This fan incorporates a novel nonmetallic "can" to keep the oxygen flow separate from the motor electronics, thus eliminating ignition potential. The nonmetallic can enables a small package size and low power consumption. To keep cost and schedule within project bounds a commercial motor controller was used. The fan design has been detailed and implemented using materials and approaches selected to address anticipated mission needs. Test data is presented to show how this fan performs relative to anticipated ventilation requirements for the EVA portable life support system. Additionally, data is presented to show tolerance to anticipated environmental factors such as acoustics, shock, and vibration. Recommendations for forward work to progress the technology readiness level and prepare the fan for the next EVA space suit system are also discussed.

Paul. Heather L.↗

NASA NTRSDate not supplied

An Overview of Nuclear Thermal Rocket Element Environmental Simulator (NTREES) Capabilities, Upgrades, and Overlaps in Advanced Material Testing Areas

The Nuclear Thermal Rocket Element Environmental Simulator (NTREES) was designed to perform non-nuclear testing of nuclear thermal rocket (NTR) fuel elements and materials. NTREES can simulate the thermal hydraulic environment within the reactor of an NTR and has been leveraged to provide data on the thermochemical, thermomechanical and thermohydraulic performance of components and materials. Active upgrades to the NTREES facility include installing a DC power supply for DC powered joule heating, a supply gas chiller for a cryogenically cool gas supply, gas pre-heaters with sample holders for testing samples too small to be inductively heated by bathing them in hot gas, and a high temperature digital image correlation (DIC) capability for measuring high temperature strains real time. In addition to NTR testing, given the commonality of high enthalpy flow environments between the reactor of an NTP engine and the aerothermal heating of high-speed flight, the unique capabilities of NTREES to provide high temperature gas flows at high pressure without combustion or electrode spallation byproducts may lend itself to additional usage of the facility beyond the original intent.

Michael P Schoenfeld↗

NASA NTRS2002

Low-Speed Fan Noise Reduction With Trailing Edge Blowing

An experimental proof-of-concept test was conducted to demonstrate reduction of rotor-stator interaction noise through rotor-trailing edge blowing. The velocity deficit from the viscous wake of the rotor blades was reduced by injecting air into the wake from a trailing edge slot. Composite hollow rotor blades with internal flow passages were designed based on analytical codes modeling the internal flow. The hollow blade with interior guide vanes creates flow channels through which externally supplied air flows from the root of the blade to the trailing edge. The impact of the rotor wake-stator interaction on the acoustics was also predicted analytically. The Active Noise Control Fan, located at the NASA Glenn Research Center, was used as the proof- of-concept test bed. In-duct mode and farfield directivity acoustic data were acquired at blowing rates (defined as mass supplied to trailing edge blowing system divided by fan mass flow) ranging from 0.5 to 2.0 percent. The first three blade passing frequency harmonics at fan rotational speeds of 1700 to 1900 rpm were analyzed. The acoustic tone power levels (PWL) in the inlet and exhaust were reduced 11.5 and -0.1, 7.2 and 11.4, 11.8 and 19.4 PWL dB, respectively. The farfield tone power levels at the first three harmonics were reduced 5.4, 10.6, and 12.4 dB PWL. At selected conditions, two-component hotwire and stator vane unsteady surface pressures were acquired. These measurements illustrate the physics behind the noise reduction.

Sutliff, Daniel L.↗

NASA NTRS2006

Variable Frequency Diverter Actuation for Flow Control

The design and development of an actively controlled fluidic actuator for flow control applications is explored. The basic device, with one input and two output channels, takes advantage of the Coanda effect to force a fluid jet to adhere to one of two axi-symmetric surfaces. The resultant flow is bi-stable, producing a constant flow from one output channel, until a disturbance force applied at the control point causes the flow to switch to the alternate output channel. By properly applying active control the output flows can be manipulated to provide a high degree of modulation over a wide and variable range of frequency and duty cycle. In this study the momentary operative force is applied by small, high speed isolation valves of which several different types are examined. The active fluidic diverter actuator is shown to work in several configurations including that in which the operator valves are referenced to atmosphere as well as to a source common with the power stream.

Culley, Dennis E.↗

NASA NTRS2017

High Lift Common Research Model for Wind Tunnel Testing: An Active Flow Control Perspective

This paper provides an overview of a research and development effort sponsored by the NASA Advanced Air Transport Technology Project to achieve the required high-lift performance using active flow control (AFC) on simple hinged flaps while reducing the cruise drag associated with the external mechanisms on slotted flaps of a generic modern transport aircraft. The removal of the external fairings for the Fowler flap mechanism could help to reduce drag by 3.3 counts. The main challenge is to develop an AFC system that can provide the necessary lift recovery on a simple hinged flap high-lift system while using the limited pneumatic power available on the aircraft. Innovative low-power AFC concepts will be investigated in the flap shoulder region. The AFC concepts being explored include steady blowing and unsteady blowing operating in the spatial and/or temporal domain. Both conventional and AFC-enabled high-lift configurations were designed for the current effort. The high-lift configurations share the cruise geometry that is based on the NASA Common Research Model, and therefore, are also open geometries. A 10%-scale High Lift Common Research Model (HL-CRM) is being designed for testing at the NASA Langley Research Center 14- by 22-Foot Subsonic Tunnel during fiscal year 2018. The overall project plan, status, HL-CRM configurations, and AFC objectives for the wind tunnel test are described.

Lin, John C.↗

NASA NTRS2001

Measurement of Microscopic Growth Rates in Float-Zone Silicon Crystals

Time dependent convective flows during crystal growth of doped semiconductors lead to fluctuations of the composition, so called dopant striations. In general, it is difficult to decide which is the main mechanism for the generation of these striations, it might be either the fluctuation of the concentration field in the melt and the extent of the solute boundary layer ahead of the solid-liquid interface or a variation of the growth velocity. Direct access to the concentration field is rather complicated to achieve, especially considering the high process temperature and the chemical activity of liquid silicon. The contribution of growth rate fluctuations to the formation of compositional fluctuations can be determined by measuring microscopic growth rates. The classical method of current pulses requires electrical feed-throughs and good electrical contacts, both are critical issues for the growth of high purity silicon crystals. Using a radiation based heating system, the heating power can be modulated very fast and effectively. We added to the normal heater power a sinusoidal off-set in the frequency range of 1 to 10 Hz, generating a narrow spaced weak rippling in the grown crystals which are superposed to the dopant striations caused by natural and by thermocapillary convection. The pulling speed was varied between 1 and 4mm/min. The microscope images of etched crystals slices have been analyzed by peak-search algorithms (measuring the spacing between each artificially induced marker) and by FFT. Performing growth experiments under a time-dependent flow regime, fluctuations of the microscopic growth velocity of Delta(v)/v(sub average) up to 50% have been measured. Damping the time-dependent convection by the use of an axial, static magnetic field of 500mT, the microscopic growth rate became constant within the resolution limit of this method. The results will be discussed using analytical methods for the calculation of microscopic growth velocity and by comparing them with measurements of temperature fluctuations in the melt during growth experiments itself.

Dold, P.↗

NASA NTRS1988

Space transportation nodes assumptions and requirements: Lunar base systems study task 2.1

The Space Transportation Nodes Assumptions and Requirements task was performed as part of the Advanced Space Transportation Support Contract, a NASA Johnson Space Center (JSC) study intended to provide planning for a Lunar Base near the year 2000. The original task statement has been revised to satisfy the following queries: (1) What vehicles are to be processed at the transportation node; (2) What is the flow of activities involved in a vehicle passing through the node; and (3) What node support resources are necessary to support a lunar scenario traffic model composed of a mix of vehicles in an active flight schedule. The Lunar Base Systems Study is concentrating on the initial years of the Phase 2 Lunar Base Scenario. The study will develop the first five years of that phase in order to define the transportation and surface systems (including mass, volumes, power requirements, and designs).

Kahn, Taher Ali↗

NASA NTRS1988

SUMER: Solar Ultraviolet Measurements of Emitted Radiation

The SUMER (solar ultraviolet measurements of emitted radiation) experiment is described. It will study flows, turbulent motions, waves, temperatures and densities of the plasma in the upper atmosphere of the Sun. Structures and events associated with solar magnetic activity will be observed on various spatial and temporal scales. This will contribute to the understanding of coronal heating processes and the solar wind expansion. The instrument will take images of the Sun in EUV (extreme ultra violet) light with high resolution in space, wavelength and time. The spatial resolution and spectral resolving power of the instrument are described. Spectral shifts can be determined with subpixel accuracy. The wavelength range extends from 500 to 1600 angstroms. The integration time can be as short as one second. Line profiles, shifts and broadenings are studied. Ratios of temperature and density sensitive EUV emission lines are established.

Wilhelm, K.↗

NASA NTRS2011

NASA Tech Briefs, December 2011

Topics covered include: 1) SNE Industrial Fieldbus Interface; 2) Composite Thermal Switch; 3) XMOS XC-2 Development Board for Mechanical Control and Data Collection; 4) Receiver Gain Modulation Circuit; 5) NEXUS Scalable and Distributed Next-Generation Avionics Bus for Space Missions; 6) Digital Interface Board to Control Phase and Amplitude of Four Channels; 7) CoNNeCT Baseband Processor Module; 8) Cryogenic 160-GHz MMIC Heterodyne Receiver Module; 9) Ka-Band, Multi-Gigabit-Per-Second Transceiver; 10) All-Solid-State 2.45-to-2.78-THz Source; 11) Onboard Interferometric SAR Processor for the Ka-Band Radar Interferometer (KaRIn); 12) Space Environments Testbed; 13) High-Performance 3D Articulated Robot Display; 14) Athena; 15) In Situ Surface Characterization; 16) Ndarts; 17) Cryo-Etched Black Silicon for Use as Optical Black; 18) Advanced CO2 Removal and Reduction System; 19) Correcting Thermal Deformations in an Active Composite Reflector; 20) Umbilical Deployment Device; 21) Space Mirror Alignment System; 22) Thermionic Power Cell To Harness Heat Energies for Geothermal Applications; 23) Graph Theory Roots of Spatial Operators for Kinematics and Dynamics; 24) Spacesuit Soft Upper Torso Sizing Systems; 25) Radiation Protection Using Single-Wall Carbon Nanotube Derivatives; 26) PMA-PhyloChip DNA Microarray to Elucidate Viable Microbial Community Structure; 27) Lidar Luminance Quantizer; 28) Distributed Capacitive Sensor for Sample Mass Measurement; 29) Base Flow Model Validation; 30) Minimum Landing Error Powered-Descent Guidance for Planetary Missions; 31) Framework for Integrating Science Data Processing Algorithms Into Process Control Systems; 32) Time Synchronization and Distribution Mechanisms for Space Networks; 33) Local Estimators for Spacecraft Formation Flying; 34) Software-Defined Radio for Space-to-Space Communications; 35) Reflective Occultation Mask for Evaluation of Occulter Designs for Planet Finding; and 36) Molecular Adsorber Coating

Source record↗

NASA NTRS2011

An Active Broad Area Cooling Model of a Cryogenic Propellant Tank with a Single Stage Reverse Turbo-Brayton Cycle Cryocooler

As focus shifts towards long-duration space exploration missions, an increased interest in active thermal control of cryogenic propellants to achieve zero boil-off of cryogens has emerged. An active thermal control concept of considerable merit is the integration of a broad area cooling system for a cryogenic propellant tank with a combined cryocooler and circulator system that can be used to reduce or even eliminate liquid cryogen boil-off. One prospective cryocooler and circulator combination is the reverse turbo-Brayton cycle cryocooler. This system is unique in that it has the ability to both cool and circulate the coolant gas efficiently in the same loop as the broad area cooling lines, allowing for a single cooling gas loop, with the primary heat rejection occurring by way of a radiator and/or aftercooler. Currently few modeling tools exist that can size and characterize an integrated reverse turbo-Brayton cycle cryocooler in combination with a broad area cooling design. This paper addresses efforts to create such a tool to assist in gaining a broader understanding of these systems, and investigate their performance in potential space missions. The model uses conventional engineering and thermodynamic relationships to predict the preliminary design parameters, including input power requirements, pressure drops, flow rate, cycle performance, cooling lift, broad area cooler line sizing, and component operating temperatures and pressures given the cooling load operating temperature, heat rejection temperature, compressor inlet pressure, compressor rotational speed, and cryogenic tank geometry. In addition, the model allows for the preliminary design analysis of the broad area cooling tubing, to determine the effect of tube sizing on the reverse turbo-Brayton cycle system performance. At the time this paper was written, the model was verified to match existing theoretical documentation within a reasonable margin. While further experimental data is needed for full validation, this tool has already made significant steps towards giving a clearer understanding of the performance of a reverse turbo-Brayton cycle cryocooler integrated with broad area cooling technology for zero boil-off active thermal control.

Guzik, Monica C.↗

NASA NTRS1972

A computer method for schedule processing and quick-time updating.

A schedule analysis program is presented which can be used to process any schedule with continuous flow and with no loops. Although generally thought of as a management tool, it has applicability to such extremes as music composition and computer program efficiency analysis. Other possibilities for its use include the determination of electrical power usage during some operation such as spacecraft checkout, and the determination of impact envelopes for the purpose of scheduling payloads in launch processing. At the core of the described computer method is an algorithm which computes the position of each activity bar on the output waterfall chart. The algorithm is basically a maximal-path computation which gives to each node in the schedule network the maximal path from the initial node to the given node.

Mccoy, W. H.↗

NASA NTRS1986

The boundary layer on compressor cascade blades

The purpose of NASA Research Grant NSG-3264 is to characterize the flowfield about an airfoil in a cascade at chord Reynolds number(R sub C)near 5 x 10 to the 5th power. The program is experimental and combines laser Doppler velocimeter (LDV) measurements with flow visualization techniques in order to obtain detailed flow data, e.g., boundary layer profiles, points of separation and the transition zone, on a cascade of highly-loaded compressor blades. The information provided by this study is to serve as benchmark data for the evaluation of current and future compressor cascade predictive models, in this way aiding in the compressor design process. Summarized is the research activity for the period 1 December 1985 through 1 June 1986. Progress made from 1 June 1979 through 1 December 1985 is presented. Detailed measurements have been completed at the initial cascade angle of 53 deg. (incidence angle 5 degrees). A three part study, based on that data, has been accepted as part of the 1986 Gas Turbine Conference and will be submitted for subsequent journal publication. Also presented are data for a second cascade angle of 45 deg (an incidence angle of 3 degrees).

Deutsch, S.↗

NASA NTRS1987

The surface age of Venus: Applying the terrestrial cratering rate

The population of Venusian craters having suspected impact crater morphology has been reported from 115 x 10 to the 6th power sq km of the northern hemisphere of the planet with the estimated average age of the surface to be approx. 1 b.y. (+ or - 0.5 b.y.) on the basis of lunar crater production curves corrected for Venus. Such an old average age is somewhat difficult to reconcile with the similarity in size and mass of Venus and Earth and with Earth's high heat flow and crustal resurfacing rate. Given the present uncertainties in the role of both active and inactive comet nuclei in the cratering history of Earth, it is concluded that the average age of the observed surface in the northern hemisphere of Venus could be as great as the 450 m.y. mean age of the Earth's crust. The surface of Venus might be even older, but no evidence from the crater observations support an age as great as 1 b.y.

Schaber, Gerald G.↗

NASA NTRS2018

An Overview of High Bandwidth Liquid Fuel Flow Modulators Developed for Active Combustion Control Research

This paper presents a description of the general construction of three high bandwidth liquid fuel modulators along with data corresponding to their respective modulation performance. These devices are a critical element of the National Aeronautics and Space Administration Glenn Research Center's (NASA GRC) Active Combustion Control (ACC) task. These devices are not commercially-off-the-shelf available, primarily due to a one kHz bandwidth requirement. Given their special nature, NASA GRC developed specifications for the modulation devices and then, through Small Business Innovative Research (SBIR) contracts, had vendors with expertise in valve design manufacture them. The modulators described in this paper are the Active Signal Modulator (ASM), the Jansen's Aircraft System Controls (JASC) modulator, and the WASK Engineering (WASK) modulator. These modulators utilize magnetostrictive, electric motor, or piezoelectric actuation, respectively. The specifications for these devices evolved over time to meet the needs of changing objectives in the ACC research task. This is primarily true with respect to flow number as their designs accommodate a range from one to eight (lbm./hr-psi0.5). These designs also exhibit relatively small volume, weight, and power consumption with an ability to modulate approximately +/- 30% from the mean on a pressure basis. The modulators have been characterized and have undergone laboratory performance tests by the vendors. Their data indicated suitability for continued use in ACC research testing.

Saus, Joseph R.↗

NASA NTRS1983

Development of a Polysilicon Process Based on Chemical Vapor Deposition of Dichlorosilane in an Advanced Siemen's Reactor

Dichlorosilane (DCS) was used as the feedstock for an advanced decomposition reactor for silicon production. The advanced reactor had a cool bell jar wall temperature, 300 C, when compared to Siemen's reactors previously used for DCS decomposition. Previous reactors had bell jar wall temperatures of approximately 750 C. The cooler wall temperature allows higher DCS flow rates and concentrations. A silicon deposition rate of 2.28 gm/hr-cm was achieved with power consumption of 59 kWh/kg. Interpretation of data suggests that a 2.8 gm/hr-cm deposition rate is possible. Screening of lower cost materials of construction was done as a separate program segment. Stainless Steel (304 and 316), Hastalloy B, Monel 400 and 1010-Carbon Steel were placed individually in an experimental scale reactor. Silicon was deposited from trichlorosilane feedstock. The resultant silicon was analyzed for electrically active and metallic impurities as well as carbon. No material contributed significant amounts of electrically active or metallic impurities, but all contributed carbon.

Arevidson, A. N.↗

NASA NTRS1993

Specification and testing for power by wire aircraft

A power by wire aircraft is one in which all active functions other than propulsion are implemented electrically. Other nomenclature are 'all electric airplane,' or 'more electric airplane.' What is involved is the task of developing and certifying electrical equipment to replace existing hydraulics and pneumatics. When such functions, however, are primary flight controls which are implemented electrically, new requirements are imposed that were not anticipated by existing power system designs. Standards of particular impact are the requirements of ultra-high reliability, high peak transient bi-directional power flow, and immunity to electromagnetic interference and lightning. Not only must the electromagnetic immunity of the total system be verifiable, but box level tests and meaningful system models must be established to allow system evaluation. This paper discusses some of the problems, the system modifications involved, and early results in establishing wiring harness and interface susceptibility requirements.

Hansen, Irving G.↗