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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 415 records · Page 23
All sourcesNASA NTRSDOE OSTI
NASA NTRS1988

Development of mid-infrared solid state lasers for spaceborne lidar

This semiannual progress report covers work performed during the period from April 13, 1988 to October 13, 1988 under NASA grant number NAG-1-877 entitled, Development of mid-infrared solid state lasers for spaceborne lidar. We have designed a flashlamp-pumped Cr3(+);GSAG laser of pulsed laser energy greater than 200 mJ and of pulse width of 1 ms FWHM to simulate a high-power laser diode in pumping mid-infrared laser crystals such as Tm3(+), Er3(+), and/or Ho3(+)-ion doped YAG, YLF or other host materials. This Cr3(+);GSAG laser will be used to determine optimum conditions for laser diode pumped mid-infrared lasers, maximum energy extraction limit with longitudinal pumping, thermal damage limit, and other problems related to high power laser diode pumping. We have completed a modification of an existing flashlamp-pumped and liquid nitrogen cooled rare earth laser system for 60 J electrical input energy and a 500 micron pulse width, and have carried out preliminary experiments with a Ho(+):Er3(+):Tm3(+):YAG crystal to test the system performance. This flashlamp-pumped rare earth laser system will be used to determine optimum Tm3(+)-ion concentration in Ho3(+):Cr3(+):Tm3(+):YAG crystal in the remaining research period.

Whitney, Donald A.↗
NASA NTRS1984

Development of the sonic pump levitation

A prototype levitating/positioning device termed the Sonic Pump Levitator was designed, built and successfully tested in full gravity and in the reduced gravity of the parabolic flight regime of the KC-135. Positioning is achieved by timely and appropriate application of gas momentum from one or more of six sonic pumps. The sonic pumps, which are arranged orthogonally in opposed pairs about the levitation region, are activated by an electro-optical, computer controlled, feedback system. The sonic pump is a transducer which is capable of converting sound energy into a directed flow of gas. It consists of a loudspeaker whose face is sealed by a closure perforated by one or more orifices. The diaphragm of the loudspeaker is the only moving part of the sonic pump, no valves being needed. This very low inertia electromechanical device was developed to provide the short response time necessary to keep pace with the demands of computerized position keeping.

Dunn, S. A.↗
NASA NTRS1994

Preliminary Calibration Report of an Apparatus to Measure Vibration Characteristics of Low Frequency Disturbance Source Devices

This report presents a description of the test apparatus and the method of testing the low frequency disturbance source characteristics of small pumps, fans, camera motors, and recorders that are typical of those used in microgravity science facilities. The test apparatus will allow both force and acceleration spectra of these disturbance devices to be obtained from acceleration measurements over the frequency range from 2 to 300 Hz. Some preliminary calibration results are presented.

Russell, James W.↗
NASA NTRS2009

Fission Surface Power Technology Development Testing at NASA's Early Flight Fission Test Facility

Fission surface power (FSP) systems could be used to provide power anytime, anywhere on the surface of the Moon or Mars. FSP systems could be used at polar locations, at locations away from the poles, or in permanently shaded regions, with excellent performance at all sites. A potential reference 40 kWe option has been devised that is cost-competitive with alternatives while providing more power for less mass anywhere on the lunar surface. The reference FSP system (FSPS) is also readily extensible for use on Mars. At Mars the system would be capable of operating through global dust storms and providing year-round power at any Martian latitude. Under the NASA Exploration Technology Development Program (ETDP), NASA and the Department of Energy (DOE) have begun technology development on Fission Surface Power (FSP). The primary customer for this technology is the NASA Constellation Program which is responsible for the development of surface systems to support human exploration on the moon and Mars. The objectives of the FSP technology project are: 1) Develop FSP concepts that meet expected surface power requirements at reasonable cost with added benefits over other options. 2) Establish a hardware-based technical foundation for FSP design concepts and reduce overall development risk. 3) Reduce the cost uncertainties for FSP and establish greater credibility for flight system cost estimates. 4) Generate the key products to allow Agency decision-makers to consider FSP as a viable option for flight development. To be mass efficient, FSP systems must operate at higher coolant temperatures and use different types of power conversion than typical terrestrial systems. The primary reason is the difficulty in rejecting excess heat to space. Although many options exist, NASA s current reference FSP system uses a fast spectrum, pumped-NaK cooled reactor coupled to a Stirling power conversion subsystem. The reference system uses technology with significant terrestrial heritage while still providing excellent performance on the surface of the moon or Mars. Recent testing at NASA s Early Flight Fission Test Facility (EFF-TF) has helped assess the viability of the reference FSP system, and has helped evaluate methods for system integration. In June, 2009, a representative pumped NaK loop (provided by Marshall Space Flight Center) was coupled to a Stirling power converter (provided by Glenn Research Center) and tested at various conditions representative of those that would be seen during actual FSP system operation. In all areas, performance of the integrated system exceeded project goals. High-temperature NaK pump testing has also been performed at the EFF-TF, as has testing of methods for providing long-duration NaK purity.

Houts. Michael G.↗
NASA NTRS1992

Ion engine endurance testing at high background pressures

Ion engine endurance testing at vacuum chamber pressures in the low 10 exp -3 Pa range is enabled through the use of a three-grid accelerator system with the decelerator grid biased 50 to 100 volts negative of neutralizer cathode potential. The negative decelerator grid serves to collect the facility induced charge exchange ion current which normally results in rapid erosion of the accelerator grid during testing at elevated vacuum chamber pressures. This screen, accelerator, negative decelerator (SAND) grid configuration enables an order of magnitude reduction in vacuum chamber pumping speeds relative to that required for endurance testing of ion engines with conventional two-grid accelerator systems. A 900-hr test of a 30-cm diameter engine at 6.5 kW and a tank pressure of 3.7 x 10 exp -3 Pa was performed to test the feasibility of the three-grid SAND accelerator system technology. Grid erosion rates from this test are compared to those from a 200-hr test performed with the same discharge chamber, in the same test facility, and at the same background pressure with a conventional two grid accelerator system. The SAND optics resulted in greater than a factor of 100 reduction in accelerator grid erosion rate relative to the two-grid system.

Brophy, John R.↗
NASA NTRS1981

Firefighting module development

The firefighting module is a lightweight, compact, self contained, helicopter-transportable unit for fighting harbor and other specialty fires as well as for use in emergency water pumping applications. Units were fabricated and tested. A production type unit is undergoing an inservice evaluation and demonstration program at the port of St Louis. The primary purpose is to promote enhanced harbor fire protection at inland and coastal ports. The module and its development are described.

Burns, R. A.↗
NASA NTRS1986

Large aperture interferometer with phase-conjugate self-reference beam

A large aperture self-referencing interferometer consisting of a Twyman-Green interferometer using a self-pumped phase conjugator in series with test section optics is described and experimentally demonstrated. This interferometer provides twice the fringe shift of a Mach-Zehnder (M-Z) interferometer for a given optical phase change induced within the test section. It also provides greater irradiance in the reference beam than does a similar series setup utilizing a M-Z interferometer incorporating a local reference beam. Whereas the ordinary interferometer records instantaneous conditions, the new one records overage conditions if a BaTiO3 crystal is used as the phase conjugator.

Howes, W. L.↗
NASA NTRS1988

Study of toluene rotary fluid management device and shear flow condenser performance for a space-based organic Rankine power system

Management of two-phase fluid and control of the heat transfer process in microgravity is a technical challenge that must be addressed for an orbital Organic Rankine Cycle (ORC) application. A test program was performed in 1-g that satisfactorily demonstrated the two-phase management capability of the rotating fluid management device (RFMD) and shear-flow condenser. Operational tests of the RFMD and shear flow condenser in adverse gravity orientations, confirmed that the centrifugal forces in the RFMD and the shear forces in the condenser were capable of overcoming gravity forces. In a microgravity environment, these same forces would not have to compete against gravity and would therefore be dominant. The specific test program covered the required operating range of the Space Station Solar Dynamic Rankine Cycle power system. Review of the test data verified that: fluid was pumped from the RFMD in all attitudes; subcooled states in the condenser were achieved; condensate was pushed uphill against gravity; and noncondensible gases were swept through the condenser.

Havens, Vance↗
NASA NTRS1991

Near-term, 100-kW class ion engines

A design approach for large area, high power ion engines is presented. This approach conceptually divides a single engine into a combination of smaller discharge chambers (or segments) configured to operate as a single large area engine. This segmented ion thruster (SIT) approach is shown to enable the immediate development of 100-kW class argon ion engines for operation at a specific impulse of 10,000 s. A combination of six 30-cm diameter ion chambers operating as a single engine can process over 100 kW. Such a segmented ion engine could be built today and would operate from a single power processor unit. The segmented engine design approach may also enable the development of megawatt class ion engines. Potential benefits of the segmented ion thruster design include: mitigation of the span-to-gap problem central to the development of large area, high power ion engines; reduction in hollow cathode emission current requirements; improved fault tolerance; and reduced vacuum system pumping speed requirements for engine development testing.

Brophy, John R.↗
NASA NTRS1925

Atomization of liquid fuels. Part II

This report describes the design and operation of a nozzle to inject fuel into an engine. The design of the nozzle is open, without any compulsory or automatic stop-valve. The fuel injection is regulated simply by the pressure and the adjustment of the fuel pump.

FUELS - TESTS↗
NASA NTRS1993

A finite-element-based perturbation model for the rotordynamic analysis of shrouded pump impellers: Part 1: Model development and applications

This study concerns the rotor dynamic characteristics of fluid-encompassed rotors, with special emphasis on shrouded pump impellers. The core of the study is a versatile and categorically new finite-element-based perturbation model, which is based on a rigorous flow analysis and what we have generically termed the 'virtually' deformable finite-element approach. The model is first applied to the case of a smooth annular seal for verification purposes. The rotor excitation components, in this sample problem, give rise to a purely cylindrical, purely conical, and a simultaneous cylindrical/conical rotor whirl around the housing centerline. In all cases, the computed results are compared to existing experimental and analytical data involving the same seal geometry and operating conditions. Next, two labyrinth-seal configurations, which share the same tooth-to-tooth chamber geometry but differ in the total number of chambers, were investigated. The results, in this case, are compared to experimental measurements for both seal configurations. The focus is finally shifted to the shrouded-impeller problem, where the stability effects of the leakage flow in the shroud-to-housing secondary passage are investigated. To this end, the computational model is applied to a typical shrouded-impeller pump stage, fabricated and rotor dynamically tested by Sulzer Bros., and the results compared to those of a simplified 'bulk-flow' analysis and Sulzer Bros.' test data. In addition to assessing the computed rotor dynamic coefficients, the shrouded-impeller study also covers a controversial topic, namely that of the leakage-passage inlet swirl, which was previously cited as the origin of highly unconventional (resonance-like) trends of the fluid-exerted forces. In order to validate this claim, a 'microscopic' study of the fluid/shroud interaction mechanism is conducted, with the focus being on the structure of the perturbed flow field associated with the impeller whirl. The conclusions of this study were solidified by the outcome of a numerical-certainty exercise, where the grid dependency of the numerical results is objectively examined. The final phase of the shrouded-impeller investigation involves the validation of a built-in assumption, in all other perturbation models, whereby single-harmonic tangential distributions of all the flow thermophysical properties are imposed. The last phase of the investigation course is aimed at verifying the fine details of the perturbed flow field in light of recent set of detailed LDA measurements in a smooth annular seal. Grid dependency of the fluid-induced forces is also investigated, and specific recommendations are made.

Baskharone, Erian A.↗
NASA NTRS2013

Determining Temperature Differential to Prevent Hardware Cross-Contamination in a Vacuum Chamber

When contamination-sensitive hardware must be tested in a thermal vacuum chamber, cross-contamination from other hardware present in the chamber, or residue from previous tests, becomes a concern. Typical mitigation strategies involve maintaining the temperature of the critical item above that of other hardware elements at the end of the test. A formula for relating the pumping speed of a chamber, the surface area of contamination sources, and the temperatures of the chamber, source, and contamination-sensitive items has been developed. The formula allows the determination of a temperature threshold about which contamination will not condense on the sensitive items. It defines a parameter alpha that is the fraction given by (contaminant source area)/[chamber pumping speed (time under vacuum) 0.5]. If this parameter is less than 10(exp -6), cross-contamination from common spacecraft material will not occur when the sensitive hardware is at the same temperature as the source of contamination (The chamber is isothermal within 5 C.). Knowing when it becomes safe to have the hardware isothermal permits faster and easier thermal transitions when compared with maintaining an arbitrary temperature differential between parts. Furthermore, the standard temperature differential may not be adequate under some conditions (alpha>10(exp -4)).

Hughes, David↗
NASA NTRS2016

Spectral Monitoring of Volatiles During Drilling into Frozen Lunar Simulant

NASA's Resource Prospector (RP) project intends to characterize the 3D distribution of volatiles in permanently shadowed regions at the lunar poles. One RP remote sensing instrument is a near-infrared spectrometer with an associated camera and radiometer, called the Near-InfraRed Volatile Spectrometer System (NIRVSS). In May 2016, NIRVSS, a Honeybee Robotics drill, and an Inficon mass spectrometer were placed in a vacuum chamber at Glenn Research Center. Also inside was a tube (1.2 m high x 25 cm diameter) filled with lunar simulant NU-LHT-3M, initially doped with a homogeneous water abundance of ~5%, chilled to cryogenic temperatures and exposed to a vacuum (~10e-6 Torr). During drilling, the NIRVSS instruments observed the cuttings pile as subsurface materials were emplaced on the surface. Spectral features associated with water ice, near 2000 and 3000 nm, were measured by the spectrometer during drilling. The spectral data documents development of a desiccated soil layer in the tube down to ~25-30 cm (confirmed by post-test soil analyses), formed during the initial pump down to vacuum. Drilling occurred in 10 cm segments, with the drill stem extracted and flutes brushed after each 10 cm depth. One exception to this was the 40 cm depth segment where the soil was delivered to a sample capture mechanism, and sealed for post-test analyses. To ~30 cm depth the greatest 2000 and 3000 nm signatures were associated with brushing of the drill flutes above the surface. At depths >40 cm the strongest ice signatures were associated with the drill clearing soil from the existing hole, or beginning to encounter new material. For these greater depths, brushing the flutes after extraction produced much weaker ice signatures than for shallower depths. This suggests that the soil may remain trapped in the exit funnel and is not emplaced on the surface. After each event creating strong ice signatures, these signatures decreased to near background levels in 5 minutes or less, due to surface exposure to vacuum.

lunar poles↗
NASA NTRS1991

Dynamic Tester For Rotor Seals And Bearings

Simplified apparatus measures performance under vibration. Measures some of dynamic parameters of rotor seals and bearings. Tests damping seals, damping bearings, conventional seals, and conventional bearings. Used with variety of pumped liquids, from water to liquid oxygen or hydrogen. Designed to test bearings and seals of turbopumps, tester rotates shaft at high speed while liquid flows much as it would in real turbopump. Also measures deflections of components.

Von Pragenau, George L.↗
NASA NTRS1973

Investigation of mercury thruster isolators

Mercury ion thruster isolator lifetime tests were performed using different isolator materials and geometries. Tests were performed with and without the flow of mercury through the isolators in an oil diffusion pumped vacuum facility and cryogenically pumped bell jar. The onset of leakage current in isolators tested occurred in time intervals ranging from a few hours to many hundreds of hours. In all cases, surface contamination was responsible for the onset of leakage current and subsequent isolator failure. Rate of increase of leakage current and the leakage current level increased approximately exponentially with isolator temperature. Careful attention to shielding techniques and the elimination of sources of metal oxides appear to have eliminated isolator failures as a thruster life limiting mechanism.

Mantenieks, M. A.↗
NASA NTRS1988

Free-flying experiment to measure the Schawlow-Townes linewidth limit of a 300 THz laser oscillator

Recent advances in laser diode-pumped solid state laser sources permit the design and testing of laser sources with linewidths that approach the Schawlow-Townes limit of 1 Hz/mW of output power. Laser diode pumped solid state ring oscillators have been operated with CW output power levels of 25 mW at electrical efficiencies that exceed 6 percent. These oscillators are expected to operate for lifetimes that approach those of the laser diode sources which is now approaching 20,000 hours. The efficiency and lifetime of these narrow linewidth laser sources will enable space measurements of gravity waves, remote sensing applications (including local range rate and measurements), and laser sources for frequency and time standards. A free-flight experiment, 'SUNLITE', is being designed to measure the linewidth of this all-solid-state laser system.

Byer, R. L.↗