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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 163 records · Page 9

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NASA NTRS1973

The hollow cathode in the quasi-steady MPD discharge

A large hollow cathode has been operated in a quasi-steady MPD discharge over a range of current from 7 to 30 kA and argon mass flow from 0.04 to 6.0 g/sec. The 1.3-cm-i.d. cathode cavity attains steady emission characteristics in some tens of microseconds without the assistance of auxiliary heating, low work function inserts, or external keeper electrodes. Measured current and potential distributions within the cavity reveal that the current attaches in a zone 1 to 2 cm long with a surface current density greater than 1000 A/sq cm and a local axial electric field less than 10 V/cm. Electron densities within the cavity, estimated from spectroscopic records, are above 10 to the 17th power per cu cm, at least one order of magnitude greater than has been reported for either ion engine hollow cathodes or conventional solid cathodes in similar arc discharges.

Von Jaskowsky, W. F.↗

NASA NTRS1976

Gait Analysis Laboratory

Complete motion analysis laboratory has evolved out of analyzing walking patterns of crippled children at Stanford Children's Hospital. Data is collected by placing tiny electrical sensors over muscle groups of child's legs and inserting step-sensing switches in soles of shoes. Miniature radio transmitters send signals to receiver for continuous recording of abnormal walking pattern. Engineers are working to apply space electronics miniaturization techniques to reduce size and weight of telemetry system further as well as striving to increase signal bandwidth so analysis can be performed faster and more accurately using a mini-computer.

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NASA NTRSDate not supplied

Highlights of the Test of the QUiet Electric Engine (QUEEN V1) in the NASA GRC Acoustical Testing Laboratory (ATL)

This presentation for the NASA Acoustics Technical Working Group meeting highlights preliminary acoustic and thermal test results from the Quiet Electric Engine (QUEEN V1) experiment recently performed in the NASA Glenn Research Center Acoustical Testing Laboratory. The QUEEN V1 features a single Commercial-Off-the-Shelf fan with an Outlet Guide Vane. Four inlet duct acoustic liners were tested. Electronic Speed Controller (ESC) temperatures were recorded for two different cooling methods: air cooling and a cold plate.

Acoustics↗

NASA NTRS1991

Isothermal Dendritic Growth Experiment - Science, engineering, and hardware development for USMP space flights

The Isothermal Dendritic Growth Experiment (IDGE) has been designed to provide microgravity data on dendritic growth for a critical test of theory. This paper updates progress on constructing a crystal growth chamber suitable for space flight. The IDGE chamber is constructed from glass and stainless steel and is hermetically sealed by electron beam welds and glass-metal seals. Initial tests of the chambers sample's melting point plateau show that the new chamber design is capable of preserving the 99.9995 percent purity of succinonitrile. Dendrite growth can be initiated in the center of the IDGE chamber by means of thermo-electric coolers and a capillary injector tube (stinger). The new IDGE chamber is ready for fully integrated tests with the prototype IDGE engineering hardware at NASA's Lewis Research Center.

Glicksman, M. E.↗

NASA NTRS2009

Insulating Foams Save Money, Increase Safety

Scientists at Langley Research Center created polyimide foam insulation for reusable cryogenic propellant tanks on the space shuttle. Meanwhile, a small Hialeah, Florida-based business, PolyuMAC Inc., was looking for advanced foams to use in the customized manufacturing of acoustical and thermal insulation. The company contacted NASA, licensed the material, and then the original inventors worked with the company's engineers to make a new material that was better for both parties. The new version, a high performance, flame retardant, flexible polyimide foam, is used for insulating NASA cryogenic propellant tanks and shows promise for use on watercraft, aircraft, spacecraft, electronics and electrical products, automobiles and automotive products, recreation equipment, and building and construction materials.

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NASA NTRS1996

Experimental Investigation of Pool Boiling Heat Transfer Enhancement in Microgravity in the Presence of Electric Fields

Boiling is an effective mode of heat transfer since high heat flux levels are possible driven by relatively small temperature differences. The high heat transfer coefficients associated with boiling have made the use of these processes increasingly attractive to aerospace engineering. Applications of this type include compact evaporators in the thermal control of aircraft avionics and spacecraft environments, heat pipes, and use of boiling to cool electronic equipment. In spite of its efficiency, cooling based on liquid-vapor phase change processes has not yet found wide application in aerospace engineering due to specific problems associated with the low gravity environment. After a heated surface has reached the superheat required for the initiation of nucleate boiling, bubbles will start forming at nucleation sites along the solid interface by evaporation of the liquid. Bubbles in contact with the wall will continue growing by this mechanism until they detach. In terrestrial conditions, bubble detachment is determined by the competition between body forces (e.g. buoyancy) and surface tension forces that act to anchor the bubble along the three phase contact line. For a given body force potential and a balance of tensions along the three phase contact line, bubbles must reach a critical size before the body force can cause them to detach from the wall. In a low gravity environment the critical bubble size for detachment is much larger than under terrestrial conditions, since buoyancy is a less effective means of bubble removal. Active techniques of heat transfer enhancement in single phase and phase change processes by utilizing electric fields have been the subject of intensive research during recent years. The field of electrohydrodynamics (EHD) deals with the interactions between electric fields, flow fields and temperature fields. Previous studies indicate that in terrestrial applications nucleate boiling heat transfer can be increased by a factor of 50 as compared to values obtained for the same system without electric fields. Imposing an external electric field holds the promise to improve pool boiling heat transfer in low gravity, since a phase separation force other than gravity is introduced. The goal of our research is to experimentally investigate the potential of EHD and the mechanisms responsible for EHD heat transfer enhancement in boiling in low gravity conditions.

Herman, Cila↗

NASA NTRS2005

Computational Model Tracking Primary Electrons, Secondary Electrons, and Ions in the Discharge Chamber of an Ion Engine

Computational modeling of the plasma located in the discharge chamber of an ion engine is an important activity so that the development and design of the next generation of ion engines may be enhanced. In this work a computational tool called XOOPIC is used to model the primary electrons, secondary electrons, and ions inside the discharge chamber. The details of this computational tool are discussed in this paper. Preliminary results from XOOPIC are presented. The results presented include particle number density distributions for the primary electrons, the secondary electrons, and the ions. In addition the total number of a particular particle in the discharge chamber as a function of time, electric potential maps and magnetic field maps are presented. A primary electron number density plot from PRIMA is given in this paper so that the results of XOOPIC can be compared to it. PRIMA is a computer code that the present investigators have used in much of their previous work that provides results that compare well to experimental results. PRIMA only models the primary electrons in the discharge chamber. Modeling ions and secondary electrons, as well as the primary electrons, will greatly increase our ability to predict different characteristics of the plasma discharge used in an ion engine.

Mahalingam, Sudhakar↗

NASA NTRS1985

Shuttle electrical environment

Part of an AFGL payload flown on the STS-4 mission consisted of experiments to measure in-situ electric fields, electron densities, and vehicle charging. During this flight some 11 hours of data were acquired ranging from 5 minute snapshots up to continuous half-orbits. These experiments are described and results presented for such vehicle induced events as a main engine burn, thruster firings and water dumps in addition to undisturbed periods. The main characteristic of all the vehicle induced events is shown to be an enhancement in the low frequency noise (less than 2 kHz), in both the electrostatic and electron irregularity (delta N/N) spectra. The non-event results indicate that the electrostatic broadband emissions show a white noise characteristic in the low frequency range up to 2 kHz at an amplitude of 10 db above the shuttle design specification limit, falling below that limit above 10 kHz. The vehicle potential remained within the range of -3 to +1 volt throughout the flight which exhibits normal behavior for a satellite in a low equatorial orbit.

Smiddy, M.↗

NASA NTRS1996

40 HP Electro-Mechanical Actuator

This report summarizes the work performed on the 40 BP electro-mechanical actuator (EMA) system developed on NASA contract NAS3-25799 for the NASA National Launch System and Electrical Actuation (ELA) Technology Bridging Programs. The system was designed to demonstrate the capability of large, high power linear ELA's for applications such as Thrust Vector Control (TVC) on rocket engines. It consists of a motor controller, high frequency power source, drive electronics and a linear actuator. The power source is a 25kVA 20 kHz Mapham inverter. The drive electronics are based on the pulse population modulation concept and operate at a nominal frequency of 40 kHz. The induction motor is a specially designed high speed, low inertia motor capable of a 68 peak HP. The actuator was originally designed by MOOG Aerospace under an internal R & D program to meet Space Shuttle Main Engine (SSME) TVC requirements. The design was modified to meet this programs linear rate specification of 7.4 inches/second. The motor and driver were tested on a dynamometer at the Martin Marietta Space Systems facility. System frequency response and step response tests were conducted at the Marshall Space Flight Center facility. A complete description of the system and all test results can be found in the body of the report.

Fulmer, Chris↗

NASA NTRS2004

Testing of Environmental Satellite Bus-Instrument Interfaces Using Engineering Models

This paper discusses the formulation and execution of a laboratory test of the electrical interfaces between multiple atmospheric science instruments and the spacecraft bus that carries them. The testing, performed in 2002, used engineering models of the instruments that will be flown on the Aura s p a c m and of the Aura spacecraft bus electronics. Aura is one of NASA's Earth Observing System @OS) Program missions managed by the Goddard Space Flight Center. The test was designed to evaluate the complex interfaces in the spacecraft and instrument command and data handling (C&DH) subsystems prior to integration of the complete flight instruments on the spacecraft. A problem discovered during (and not before) the flight hardware integration phase can cause significant cost and schedule impacts. The testing successfully surfaced problems and led to their resolution before the full-up integration phase, saving significant cost and schedule time. This approach could be used on future environmental satellite programs involving multiple, complex scientific instruments being integrated onto a bus.

Gagnier, Don↗

NASA NTRS2017

Technical Challenges and Barriers Affecting Turbo-Electric and Hybrid Electric Aircraft Propulsion

In order to meet aggressive aircraft performance goals set by NASA's Aeronautics Research Mission Directorate, the Glenn Research Center (GRC) is leading research and development of electrified aircraft propulsion systems with electricity being generated from a gas turbine engine or combination of gas turbine engine and an alternate energy source. The presentation will provide an overview of technical challenges and barriers affecting the development and implementation of turboelectric and hybrid electric systems. Advances will be required in multiple areas, which include energy storage, electrical machines, power transmission, power electronics, control systems, materials, thermal management, and multi-scale modeling tools. The presentation will summarize current GRC activities in these areas. Challenges associated with integration and demonstration of multiple technologies at the system level will be presented.

Propulsion↗

NASA NTRS1992

Experimenter's data package for the descending layers rocket

In response to a proposal from Science Applications International Corporation (SAIC), NASA Headquarters has approved a sounding rocket mission designed to study the physics of intermediate layers in the Earth's ionosphere at middle latitudes. The experiment will be carried out by a team of scientists and engineers from the NASA Wallops Flight Facility, SAIC, the NASA Goddard Space Flight Center, and the Millstone Hill radar observatory. The mission will involve the launch of an instrumented sounding rocket from the Wallops Island rocket range in the summer of 1994, with the objective of penetrating a descending ionized layer in the E-region between altitudes of 115 and 140 km. Instrumentation aboard the rocket will measure the ion and neutral composition of the layer, its plasma density, driving wind and electric field forces, the thermal ion distribution function, and electron temperature. Depending on payload weight constraints and subject to availability, a particle detector to measure energetic ion and/or electron fluxes near the layer may also be included. This document was prepared as a reference for the NASA payload development and experiment teams, for distribution at the Project Initiation Conference (PIC). The design specifications discussed herein are therefore of a preliminary nature; the intent is to promote open discussions between experimenters and NASA engineers that will lead to a final design capable of achieving the experiment objectives.

Earle, Greg↗

NASA NTRS1988

Electrode erosion in steady-state electric propulsion engines

The anode and cathode of a 30 kW class arcjet engine were sectioned and analyzed. This arcjet was operated for a total time of 573 hr at power levels between 25 and 30 kW with ammonia at flow rates of 0.25 and 0.27 gm/s. The accumulated run time was sufficient to clearly establish erosion patterns and their causes. The type of electron emission from various parts of the cathode surface was made clear by scanning electron microscope analysis. A scanning electron microscope was used to study recrystallization on the hot anode surface. These electrodes were made of 2 percent thoriated tungsten and the surface thorium content and gradient perpendicular to the surfaces was determined by quantitative microprobe analysis. The results of this material analysis on the electrodes and recommendations for improving electrode operational life time are presented.

Pivirotto, Thomas J.↗

NASA NTRS2006

Cryogenic Cooling for Myriad Applications-A STAR Is Born

Cryogenics, the science of generating extremely low temperatures, has wide applicability throughout NASA. The Agency employs cryogenics for rocket propulsion, high-pressure gas supply, breathable air in space, life support equipment, electricity, water, food preservation and packaging, medicine, imaging devices, and electronics. Cryogenic liquid oxygen and liquid hydrogen systems are also replacing solid rocket motor propulsion systems in most of the proposed launch systems, a reversion to old-style liquid propellants. In the late 1980s, NASA wanted a compact linear alternator/motor with reduced size and mass, as well as high efficiency, that had unlimited service life for use in a thermally driven power generator for space power applications. Prior development work with free-piston Stirling converters (a Stirling engine integrated with a linear actuator that produces electrical power output) had shown the promise of that technology for high-power space applications. A dual use for terrestrial applications exists for compact Stirling converters for onsite combined heat and power units. The Stirling cycle is also usable in reverse as a refrigeration cycle suitable for cryogenic cooling, so this Stirling converter work promised double benefits as well as dual uses. The uses for cryogenic coolers within NASA abound; commercial applications are similarly wide-ranging, from cooling liquid oxygen and nitrogen, to cryobiology and bio-storage, cryosurgery, instrument and detector cooling, semiconductor manufacturing, and support service for cooled superconducting power systems.

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NASA NTRS2002

Ferroelectric Emission Cathodes for Low-Power Electric Propulsion

Low- or no-flow electron emitters are required for low-power electric thrusters, spacecraft plasma contactors, and electrodynamic tether systems to reduce or eliminate the need for propellant/expellant. Expellant-less neutralizers can improve the viability of very low-power colloid thrusters, field emission electric propulsion devices, ion engines, Hall thrusters, and gridded vacuum arc thrusters. The NASA Glenn Research Center (GRC) is evaluating ferroelectric emission (FEE) cathodes as zero expellant flow rate cathode sources for the applications listed above. At GRC, low voltage (100s to approx. 1500 V) operation of FEE cathodes is examined. Initial experiments, with unipolar, bipolar, and RF burst applied voltage, have produced current pulses 250 to 1000 ns in duration with peak currents of up to 2 A at voltages at or below 1500 V. In particular, FEE cathodes driven by RF burst voltages from 1400 to 2000 V peak to peak, at burst frequencies from 70 to 400 kHz, emitted average current densities from 0.1 to 0.7 A/sq cm. Pulse repeatability as a function of input voltage has been initially established. Reliable emission has been achieved in air background at pressures as high as 10(exp -6) Torr.

Kovaleski, Scott D.↗

NASA NTRS2010

Direct Electricity from Heat: A Solution to Assist Aircraft Power Demands

A thermionic device produces an electrical current with the application of a thermal gradient whereby the temperature at one electrode provides enough thermal energy to eject electrons. The system is totally predicated on the thermal gradient and the work function of the electrode collector relative to the emitter electrode. Combined with a standard thermoelectric device high efficiencies may result, capable of providing electrical energy from the waste heat of gas turbine engines.

Goldsby, Jon C.↗

NASA NTRS2007

High Temperature Wireless Communication And Electronics For Harsh Environment Applications

In order for future aerospace propulsion systems to meet the increasing requirements for decreased maintenance, improved capability, and increased safety, the inclusion of intelligence into the propulsion system design and operation becomes necessary. These propulsion systems will have to incorporate technology that will monitor propulsion component conditions, analyze the incoming data, and modify operating parameters to optimize propulsion system operations. This implies the development of sensors, actuators, and electronics, with associated packaging, that will be able to operate under the harsh environments present in an engine. However, given the harsh environments inherent in propulsion systems, the development of engine-compatible electronics and sensors is not straightforward. The ability of a sensor system to operate in a given environment often depends as much on the technologies supporting the sensor element as the element itself. If the supporting technology cannot handle the application, then no matter how good the sensor is itself, the sensor system will fail. An example is high temperature environments where supporting technologies are often not capable of operation in engine conditions. Further, for every sensor going into an engine environment, i.e., for every new piece of hardware that improves the in-situ intelligence of the components, communication wires almost always must follow. The communication wires may be within or between parts, or from the engine to the controller. As more hardware is added, more wires, weight, complexity, and potential for unreliability is also introduced. Thus, wireless communication combined with in-situ processing of data would significantly improve the ability to include sensors into high temperature systems and thus lead toward more intelligent engine systems. NASA Glenn Research Center (GRC) is presently leading the development of electronics, communication systems, and sensors capable of prolonged stable operation in harsh 500C environments. This has included world record operation of SiC-based transistor technology (including packaging) that has demonstrated continuous electrical operation at 500C for over 2000 hours. Based on SiC electronics, development of high temperature wireless communication has been on-going. This work has concentrated on maturing the SiC electronic devices for communication purposes as well as the passive components such as resistors and capacitors needed to enable a high temperature wireless system. The objective is to eliminate wires associated with high temperature sensors which add weight to a vehicle and can be a cause of sensor unreliability. This paper discusses the development of SiC based electronics and wireless communications technology for harsh environment applications such as propulsion health management systems and in Venus missions. A brief overview of the future directions in sensor technology is given including maturing of near-room temperature "Lick and Stick" leak sensor technology for possible implementation in the Crew Launch Vehicle program. Then an overview of high temperature electronics and the development of high temperature communication systems is presented. The maturity of related technologies such as sensor and packaging will also be discussed. It is concluded that a significant component of efforts to improve the intelligence of harsh environment operating systems is the development and implementation of high temperature wireless technology

Hunter, G. W.↗

NASA NTRS1993

Plasma contactor development for Space Station

Plasma contactors have been baselined for the Space Station (SS) to control the electrical potentials of surfaces to eliminate/mitigate damaging interactions with the space environment. The system represents a dual-use technology which is a direct outgrowth of the NASA electric propulsion program and, in particular, the technology development effort on ion thrustor systems. The plasma contactor subsystems include the plasma contactor unit, a power electronics unit, and an expellant management unit. Under this pre-flight development program these will all be brought to breadboard or engineering model status. Development efforts for the plasma contactor include optimizing the design and configuration of the contactor, validating its required lifetime, and characterizing the contactor plume and electromagnetic interference. The plasma contactor unit design selected for the SS is an enclosed keeper, xenon hollow cathode plasma source. This paper discusses the test results and development status of the plasma contactor unit subsystem for the SS.

Patterson, Michael J.↗