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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 343 records · Page 19
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Liquid Nitrogen Testing of an Integrated Reaction Control System

Integrated Reaction Control Systems (IRCS) are considered an enabling technology for future human exploration of the solar system. An IRCS uses the same fuel and oxidizer as the main propulsion system, allowing for increased performance and simplified cryogenic fluid management operations. The IRCS team at Marshall Spaceflight Center is currently evaluating an IRCS system that uses a combination of electric pumps and pressure-regulation devices to provide a constant flow of conditioned propellant to a thruster bank during operation. In contrast to accumulator and gasifier designs, the recirculation loop design is less massive and can provide large, sustained flowrates to the thruster inlet. In the summer 2021 test series presented herein, the feasibility of this concept was evaluated using liquid nitrogen as a simulant for liquid oxygen. The goals of this test series were to demonstrate the ability of the pump and pressure regulator to maintain adequate thruster inlet conditions during transient operation, and to demonstrate the ability for the system to operate in an “idle mode” that maintains system chill between activations. During test operations, the back-pressure regulator responded more slowly than the opening/closing of valves in the thruster simulant, but it was still able to attenuate the pressure fluctuation at the pump discharge and ensure a stable flowrate through the pump. Similarly, the pump was able to be run far below its nominal operating point and successfully flow sufficient fluid to maintain chill conditions.

integrated RCS↗
NASA NTRSDate not supplied

Liquid Nitrogen Testing of an Integrated Reaction Control System

Integrated Reaction Control Systems (IRCS) are considered an enabling technology for future human exploration of the solar system. An IRCS uses the same fuel and oxidizer as the main propulsion system, allowing for increased performance and simplified cryogenic fluid management operations. The IRCS team at Marshall Spaceflight Center is currently evaluating an IRCS system that uses a combination of electric pumps and pressure-regulation devices to provide a constant flow of conditioned propellant to a thruster bank during operation. In contrast to accumulator and gasifier designs, the recirculation loop design is less massive and can provide large, sustained flowrates to the thruster inlet. In the summer 2021 test series presented herein, the feasibility of this concept was evaluated using liquid nitrogen as a simulant for liquid oxygen. The goals of this test series were to demonstrate the ability of the pump and pressure regulator to maintain adequate thruster inlet conditions during transient operation, and to demonstrate the ability for the system to operate in an “idle mode” that maintains system chill between activations. During test operations, the back-pressure regulator responded more slowly than the opening/closing of valves in the thruster simulant, but it was still able to attenuate the pressure fluctuation at the pump discharge and ensure a stable flowrate through the pump. Similarly, the pump was able to be run far below its nominal operating point and successfully flow sufficient fluid to maintain chill conditions.

integrated RCS↗
NASA NTRS1979

Voltage-current-power meter for photovoltaic solar arrays

A meter is disclosed for measuring the voltage, current, and power (VIP) parameters of a photovoltaic solar array, or array module, under sunlight operating conditions utilizing a variable load connected across the array and controlled by a voltage regulator which responds to the difference between the output voltage of the array and a programmed test voltage from a source which generates a single ramp voltage for measuring and recording current as a function of voltage, repeated ramp voltages at a high rate for peak output measurements or a DC voltage for VIP measurements at selected points on the I-V characteristic curve of the array. The voltage signal from a current sensing element, such as a shunt resistor in series with the variable load, is compared with the output current of a reference solar cell to provide a normalizing signal to be added to the signal from the current-sensing element in order to provide a record of array current as a function of array voltage, i.e., for all load conditions from short circuit to open circuit. As the normalized current is thus measured, an analog multiplier multiplies the array voltage and normalized current to provide a measurement of power. Switches are provided to selectively connect the power, P, current, I, or voltage, V, to a meter, directly or through a peak detector. At the same time any one of the parameters V, I and P may be recorded as a function of any other parameter.

Ross, Ronald G.↗
NASA NTRS1977

Proceedings of the 8th Precise Time and Time Interval (PTTI) Applications and Planning Meeting

The Proceedings contain the papers presented at the Eight Annual Precise Time and Tme Interval PTTI Applications and Planning Meeting. The edited record of the discussions following the papers and the panel discussions are also included. This meeting provided a forum for the exchange of information on precise time and frequency technology among members of the scientific community and persons with program applications. The 282 registered attendees came from various U.S. Government agencies, private industry, universities and a number of foreign countries were represented. In this meeting, papers were presented that emphasized: (1) definitions and international regulations of precise time sources and users, (2) the scientific foundations of Hydrogen Maser standards, the current developments in this field and the application experience, and (3) how to measure the stability performance properties of precise standards. As in the previous meetings, update and new papers were presented on system applications with past, present and future requirements identified.

Source record↗
NASA NTRS1982

Thematic mapper flight model preshipment review data package. Volume 4: Appendix. Part C: Power supply data

The acceptance test data package for the thematic mapper flight model power supply was reviewed and the data compared to the relevant specification. The power supply was found to be within specification. Final test data for outut voltage regulation and ripple, efficiency, over and undervoltage protection, telemetry, impedances, turn-on requirements, and input current limits are presented.

Source record↗
NASA NTRS1989

Power conditioning electronics for a 500 Wh inertial energy storage system

A description is given of a pulse-width-modulated buck-boost converter designed to interface a 500 Wh inertial energy storage system operating from 70 to 140 VDC to a constant bus of 150 VDC. Implementation of hysteresis feedback control provides excellent voltage regulation. The design is based on a 300-Wh, 94 percent Wh efficient prototype and is currently being optimized to yield 97 percent overall watt-hour efficiency.

Eakin, Vickie J.↗
NASA NTRS2013

Magnetostrictive Pressure Regulating System

A magnetostrictive pressure regulating system includes a magnetostrictive valve that incorporates a magnetostrictive actuator with at least one current-carrying coil disposed thereabout. A pressure force sensor, in fluid communication with the fluid exiting the valve, includes (i) a magnetostrictive material, (ii) a magnetic field generator in proximity to the magnetostrictive material for inducing a magnetic field in and surrounding the magnetostrictive material wherein lines of magnetic flux passing through the magnetostrictive material are defined, and (iii) a sensor positioned adjacent to the magnetostrictive material and in the magnetic field for measuring changes in at least one of flux angle and flux density when the magnetostrictive material experiences an applied force that is aligned with the lines of magnetic flux. The pressure of the fluid exiting the valve causes the applied force. A controller coupled to the sensor and to the current-carrying coil adjusts a current supplied to the current-carrying coil based on the changes so-measured.

Richard, James A.↗
NASA NTRS2018

GrassPlot - a Database of Multi-Scale Plant Diversity in Palaearctic Grasslands

GrassPlot is a collaborative vegetation-plot database organised by the Eurasian Dry Grassland Group (EDGG)and listed in the Global Index of Vegetation-Plot Databases (GIVD ID EU-00-003). GrassPlot collects plot records (releves) from grasslands and other open habitats of the Palaearctic biogeographic realm. It focuses on precisely delimited plots of eight standard grain sizes (0.0001; 0.001; ... 1,000 m_) and on nested-plot series withat least four different grain sizes. The usage of GrassPlot is regulated through Bylaws that intend to balance the interests of data contributors and data users. The current version (v. 1.00) contains data for approximately 170,000 plots of different sizes and 2,800 nested-plot series. The key components are richness data and metadata.However, most included datasets also encompass compositional data. About 14,000 plots have near-complete records of terricolous bryophytes and lichens in addition to vascular plants. At present, GrassPlot contains data from 36 countries throughout the Palaearctic, spread across elevational gradients and major grassland types. GrassPlot with its multi-scale and multi-taxon focus complements the larger international vegetation plot databases, such as the European Vegetation Archive (EVA) and the global database "sPlot". Its main aim is to facilitate studies on the scale- and taxon-dependency of biodiversity patterns and drivers along macroecological gradients. GrassPlot is a dynamic database and will expand through new data collection coordinated by the elected Governing Board. We invite researchers with suitable data to join GrassPlot. Researchers with project ideas addressable with GrassPlot data are welcome to submit proposals to the Governing Board.

Dengler, Jurgen↗
NASA NTRSDate not supplied

Initial Regulatory and Certification Approach for the SUSAN Electrofan Concept

New aircraft concepts and associated technologies are required to meet emerging environ-mental impact goals, while still meeting established airworthiness certification standards and regulations. The SUbsonic Single Aft eNgine (SUSAN) Electrofan is one of these concepts, utilizing a single aft-mounted engine, electrified aircraft propulsion, and an emergency backup battery. This paper explores the current certification and regulatory barriers to this novel aircraft design and the potential methods for adapting certification and regulatory requirements for the SUSAN Electrofan concept. Although some certification requirements, such as the Extended Operations regulations for continued operation after the loss of an engine, can be met with only minor changes, other requirements require modifications to the regulations or the aircraft concept for compliance. Early insight to the certification approach for the SUSAN concept, while the design is still undergoing trade space exploration, allows the development of the aircraft alongside any modifications to certification standards.

SUSAN Electrofan↗
NASA NTRS1971

A closely regulated TWT converter.

The design concept for the TWT amplifier converter for possible use in the Thermoelectric Outer Planet Spacecraft (TOPS) is presented. An unusual combination of semiconductors and magnetics was utilized to achieve very stable voltage regulation on a number of separate outputs to satisfy the requirements of a high-power TWT, and at the same time operate at an efficiency of better than 90% from a 30-V source. The circuitry consists of an output filter, an auxiliary Jensen oscillator driving a high-reactance transformer to provide current limiting to the heater, a variable time delay, a main Jensen oscillator driving the power transformer with a maximum step-up ratio of 120 to 1, and series transistorized post regulators to provide precise voltage adjustment and low output impedance. This paper discusses the design of the high-reactance transformer and the high step-up ratio transformer, as well as the high-voltage series regulators that are limited in range and operate at the top of the unregulated output voltage. Test data are presented, and details of current transients caused by charging the filter circuits, input current ripple, and output voltage ripples are considered.

Hopper, D. J.↗
NASA NTRS1974

Development and planning and design of equipment pumping generator of semiconductor lasers

The schematic of a multidimensional current pulse generator is studied. A MTKh-90 cold cathode thyratron is used as the current commutator. In the autooscillation mode on a frequency of 380 hertz the generator creates a current to 100 amps per pulse in a control resistance of 1 ohm. The pulse duration is regulated within the limits from 0.1 to 3.0 microseconds.

Popkov, A. V.↗
NASA NTRS1979

Middle atmosphere electrodynamics: Report of the workshop on the Role of the Electrodynamics of the Middle Atmosphere on Solar Terrestrial Coupling

Significant deficiencies exist in the present understanding of the basic physical processes taking place within the middle atmosphere (the region between the tropopause and the mesopause), and in the knowledge of the variability of many of the primary parameters that regulate Middle Atmosphere Electrodynamics (MAE). Knowledge of the electrical properties, i.e., electric fields, plasma characteristics, conductivity and currents, and the physical processes that govern them is of fundamental importance to the physics of the region. Middle atmosphere electrodynamics may play a critical role in the electrodynamical aspects of solar-terrestrial relations. As a first step, the Workshop on the Role of the Electrodynamics of the Middle Atmosphere on Solar-Terrestrial Coupling was held to review the present status and define recommendations for future MAE research.

Maynard, N. C.↗
NASA NTRS1977

Generalized computer-aided discrete time domain modeling and analysis of dc-dc converters

A generalized discrete time domain modeling and analysis technique is presented for all types of switching regulators using any type of duty-cycle controller, and operating in both continuous and discontinuous inductor current. State space techniques are employed to derive an equivalent nonlinear discrete time model that describes the converter exactly. The system is linearized about its equilibrium state to obtain a linear discrete time model for small signal performance evaluations, such as stability, audiosusceptibility and transient response. The analysis makes extensive use of the digital computer as an analytical tool. It is universal, exact and easy to use.

Lee, F. C.↗
NASA NTRS1999

PARC Analysis of the NASA/GE 2D NRA Mixer/Ejector Nozzle

Interest in developing a new generation supersonic transport has increased in the past several years. Current projections indicate this aircraft would cruise at approximately Mach 2.4, have a range of 5000 nautical miles and carry at least 250 passengers. A large market for such an aircraft will exist in the next century due to a predicted doubling of the demand for long range air transportation by the end of the century and the growing influence of the Pacific Rim nations. Such a proposed aircraft could more than halve the flying time from Los Angeles to Tokyo. However, before a new economically feasible supersonic transport can be built, many key technologies must be developed. Among these technologies is noise suppression. Propulsion systems for a supersonic transport using current technology would exceed acceptable noise levels. All new aircraft must satisfy FAR 36 Stage III noise regulations. The largest area of concern is the noise generated during takeoff. A concerted effort under NASA's High Speed Research (HSR) program has begun to address the problem of noise suppression. One of the most promising concepts being studied in the area of noise suppression is the mixer/ejector nozzle. This study analyzes a typical noise suppressing mixer ejector nozzle at take off conditions, using a Full Navier-Stokes (FNS) computational fluid dynamics (CFD) code.

DeBonis, J. R.↗
NASA NTRS2006

Air Quality Science and Regulatory Efforts Require Geostationary Satellite Measurements

Air quality scientists and regulatory agencies would benefit from the high spatial and temporal resolution trace gas and aerosol data that could be provided by instruments on a geostationary platform. More detailed time-resolved data from a geostationary platform could be used in tracking regional transport and in evaluating mesoscale air quality model performance in terms of photochemical evolution throughout the day. The diurnal cycle of photochemical pollutants is currently missing from the data provided by the current generation of atmospheric chemistry satellites which provide only one measurement per day. Often peak surface ozone mixing ratios are reached much earlier in the day during major regional pollution episodes than during local episodes due to downward mixing of ozone that had been transported above the boundary layer overnight. The regional air quality models often do not simulate this downward mixing well enough and underestimate surface ozone in regional episodes. Having high time-resolution geostationary data will make it possible to determine the magnitude of this lower-and mid-tropospheric transport that contributes to peak eight-hour average ozone and 24-hour average PM2.5 concentrations. We will show ozone and PM(sub 2.5) episodes from the CMAQ model and suggest ways in which geostationary satellite data would improve air quality forecasting. Current regulatory modeling is typically being performed at 12 km horizontal resolution. State and regional air quality regulators in regions with complex topography and/or land-sea breezes are anxious to move to 4-km or finer resolution simulations. Geostationary data at these or finer resolutions will be useful in evaluating such models.

Pickering, Kenneth E.↗
NASA NTRS2007

Development of a Linear Stirling Model with Varying Heat Inputs

The linear model of the Stirling system developed by NASA Glenn Research Center (GRC) has been extended to include a user-specified heat input. Previously developed linear models were limited to the Stirling convertor and electrical load. They represented the thermodynamic cycle with pressure factors that remained constant. The numerical values of the pressure factors were generated by linearizing GRC s non-linear System Dynamic Model (SDM) of the convertor at a chosen operating point. The pressure factors were fixed for that operating point, thus, the model lost accuracy if a transition to a different operating point were simulated. Although the previous linear model was used in developing controllers that manipulated current, voltage, and piston position, it could not be used in the development of control algorithms that regulated hot-end temperature. This basic model was extended to include the thermal dynamics associated with a hot-end temperature that varies over time in response to external changes as well as to changes in the Stirling cycle. The linear model described herein includes not only dynamics of the piston, displacer, gas, and electrical circuit, but also the transient effects of the heater head thermal inertia. The linear version algebraically couples two separate linear dynamic models, one model of the Stirling convertor and one model of the thermal system, through the pressure factors. The thermal system model includes heat flow of heat transfer fluid, insulation loss, and temperature drops from the heat source to the Stirling convertor expansion space. The linear model was compared to a nonlinear model, and performance was very similar. The resulting linear model can be implemented in a variety of computing environments, and is suitable for analysis with classical and state space controls analysis techniques.

Regan, Timothy F.↗
NASA NTRS2007

Development of a Linear Stirling System Model with Varying Heat Inputs

The linear model of the Stirling system developed by NASA Glenn Research Center (GRC) has been extended to include a user-specified heat input. Previously developed linear models were limited to the Stirling convertor and electrical load. They represented the thermodynamic cycle with pressure factors that remained constant. The numerical values of the pressure factors were generated by linearizing GRC's nonlinear System Dynamic Model (SDM) of the convertor at a chosen operating point. The pressure factors were fixed for that operating point, thus, the model lost accuracy if a transition to a different operating point were simulated. Although the previous linear model was used in developing controllers that manipulated current, voltage, and piston position, it could not be used in the development of control algorithms that regulated hot-end temperature. This basic model was extended to include the thermal dynamics associated with a hot-end temperature that varies over time in response to external changes as well as to changes in the Stirling cycle. The linear model described herein includes not only dynamics of the piston, displacer, gas, and electrical circuit, but also the transient effects of the heater head thermal inertia. The linear version algebraically couples two separate linear dynamic models, one model of the Stirling convertor and one model of the thermal system, through the pressure factors. The thermal system model includes heat flow of heat transfer fluid, insulation loss, and temperature drops from the heat source to the Stirling convertor expansion space. The linear model was compared to a nonlinear model, and performance was very similar. The resulting linear model can be implemented in a variety of computing environments, and is suitable for analysis with classical and state space controls analysis techniques.

Regan, Timothy F.↗
NASA NTRS2014

A Five-year Performance Study of Low VOC Coatings over Zinc Thermal Spray for the Protection of Carbon Steel at the Kennedy Space Center

The launch facilities at the Kennedy Space Center (KSC) are located approximately 1000 feet from the Atlantic Ocean where they are exposed to salt deposits, high humidity, high UV degradation, and acidic exhaust from solid rocket boosters. These assets are constructed from carbon steel, which requires a suitable coating to provide long-term protection to reduce corrosion and its associated costs. While currently used coating systems provide excellent corrosion control performance, they are subject to occupational, safety, and environmental regulations at the Federal and State levels that limit their use. Many contain high volatile organic compounds (VOCs), hazardous air pollutants, and other hazardous materials. Hazardous waste from coating operations include vacuum filters, zinc dust, hazardous paint related material, and solid paint. There are also worker safety issues such as exposure to solvents and isocyanates. To address these issues, top-coated thermal spray zinc coating systems were investigated as a promising environmentally friendly corrosion protection for carbon steel in an acidic launch environment. Additional benefits of the combined coating system include a long service life, cathodic protection to the substrate, no volatile contaminants, and high service temperatures. This paper reports the results of a performance based study to evaluate low VOC topcoats (for thermal spray zinc coatings) on carbon steel for use in a space launch environment.

Zinc Thermal Spray↗