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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 NTRS1982

Damping of thermoacoustic oscillations

A commonly encountered and troublesome problem in cryogenic systems is related to the occurrence of thermoacoustic oscillations (TAO). The oscillations are accompanied by large heat fluxes which can cause large increases in the boiloff from dewars. Such a boiloff can lead to a serious degradation in performance. It appears, therefore, highly advisable to incorporate mechanisms for damping TAO in those parts of the system where there oscillations might occur. The present investigation is concerned with the criteria for the design of such damping mechanisms. Attention is given to the theory regrading the suppression of TAO, a damper consisting of a capillary with a surge tank, and porous solid dampers.

Tward, E.↗
NASA NTRS1984

Cryogenic and thermal design for the Space Infrared Telescope Facility (SIRTF)

The 1-meter class cryogenically cooled Space Infrared Telescope Facility (SIRTF) planned by NASA, is scheduled for a 1992 launch. SIRTF would be deployed from the Shuttle, and placed into a sun synchronous polar orbit of 700 km. The facility has been defined for a mission with a minimum initial lifetime of one year in orbit with mission extension that could be made possible through in-orbit servicing of the superfluid helium cryogenic system, and use of a thermal control system. The superfluid dewar would use an orbital disconnect system for the tank supports, and vapor cooling of the barrel baffle. The transient analysis of the design shows that the superfluid helium tank with no active feedback comes within temperature requirements for the nominal orbital aperture heat load, quiescent instrument, and chopper conditions.

Lee, J. H.↗
NASA NTRS1985

Germanium resistance thermometer calibration at superfluid helium temperatures

The rapid increase in resistance of high purity semi-conducting germanium with decreasing temperature in the superfluid helium range of temperatures makes this material highly adaptable as a very sensitive thermometer. Also, a germanium thermometer exhibits a highly reproducible resistance versus temperature characteristic curve upon cycling between liquid helium temperatures and room temperature. These two factors combine to make germanium thermometers ideally suited for measuring temperatures in many cryogenic studies at superfluid helium temperatures. One disadvantage, however, is the relatively high cost of calibrated germanium thermometers. In space helium cryogenic systems, many such thermometers are often required, leading to a high cost for calibrated thermometers. The construction of a thermometer calibration cryostat and probe which will allow for calibrating six germanium thermometers at one time, thus effecting substantial savings in the purchase of thermometers is considered.

Mason, F. C.↗
NASA NTRS1985

Vapor-liquid phase separator studies

A study of porous plug use for vapor-liquid phase seperation in spaceborne cryogenic systems was conducted. The three main topics addressed were: (1) the usefulness of porous media in designs that call for variable areas and flow rates; (2) the possibility of prediction of main parameters of porous plugs for a given material; and (3) prediction of all parameters of the plug, including secondary parameters.

Yuan, S. W. K.↗
NASA NTRS1985

Long life feasibility study for SIRTF

The Phase A baseline for the Shuttle Infrared Telescope Facility (SIRTF) consists of an 85-cm diameter Cassegrain telescope, cooled to temperatures in the range from 10 to 20 K to provide background limited imaging for up to six instruments contained within a multiple instrument chamber (MIC). Colder temperature zones are also provided. A cryogenics system for a 15-day mission lifetime was first considered. In another study, the feasibility was assessed to extend the lifetime of the baseline SIRTF concept to at least six months, taking into account a mission involving the use of a space platform or a free-flyer configuration. According to the considered requirements, the optics temperature is to be kept below 10 K for at least 30 days. The temperatures are not to exceed 20 K at the end of the six months mission. It is shown that by using solid hydrogen, long-life operation is feasible with present technology.

Naes, L. G.↗
NASA NTRS1987

Clipper for High-Impedance Current-Drive Line

New circuit leakage reduced by shunting current through saturated input at operational-amplifier follower already part of Howland, or equivalent, current source. Typical application is in circuit of germanium resistance thermometer in cryogenic system.

Woodhouse, Christopher E.↗
NASA NTRS1987

Space station experiment definition: Long term cryogenic fluid storage

A preliminary design of an experiment to demonstrate and evaluate long-term cryogenic fluid storage and transfer technologies has been performed. This Long-Term Cryogenic Fluid Storage (LTCFS) experiment is a Technology Development Mission (TDM) experiment proposed by the NASA Lewis Research Center to be deployed on the Initial Operational Capability (IOC) space station. Technologies required by future orbital cryogenic systems such as Orbital Transfer Vehicles (OTV's) were defined, and critical technologies requiring demonstration were chosen to be included in the experiment. A three-phase test program was defined to test the following types of technologies: (1) Passive Thermal Technologies; (2) Fluid Transfer Technologies; and (3) Active Refrigeration Technologies. The development status of advanced technologies required for the LTCFS experiment is summarized, including current, past and future programs.

Riemer, David H.↗
NASA NTRS1987

Application of powder metallurgy technique to produce improved bearing elements for cryogenic aerospace engine turbopumps

Traditionally, vacuum melted 440C stainless steel is used for high performance bearings for aerospace cryogenic systems where corrosion due to condensation is a major concern. For the Space Shuttle Main Engine (SSME), however, 440C performance in the high-pressure turbopumps has been marginal. A basic assumption of this study was that powder metallurgy, rather than cast/wrought, processing would provide the finest, most homogeneous bearing alloy structure. Preliminary testing of P/M alloys (hardness, corrosion resistance, wear resistance, fatigue resistance, and fracture toughness) was used to 'de-select' alloys which did perform as well as baseline 440C. Five out of eleven candidate materials (14-4/6V, X-405, MRC-2001, T-440V, and D-5) based on preliminary screening were selected for the actual rolling-sliding five-ball testing. The results of this test were compared with high-performance vacuum-melted M50 bearing steel. The results of the testing indicated outstanding performance of two P/M alloys, X-405 and MRC-2001, which eventually will be further evaluated by full-scale bearing testing.

Moxson, V. S.↗
NASA NTRS1989

Miniature Centrifugal Compressor

Miniature turbocompressor designed for reliability and long life. Cryogenic system includes compressor, turboexpander, and heat exchanger provides 5 W of refrigeration at 70 K from 150 W input power. Design speed of machine 510,000 rpm. Compressor has gas-lubricated journal bearings and magnetic thrust bearing. When compressor runs no bearing contact and no wear.

Sixsmith, Herbert↗
NASA NTRS1988

Technology for Future NASA Missions: Civil Space Technology Initiative (CSTI) and Pathfinder

Information is presented in viewgraph form on a number of related topics. Information is given on orbit transfer vehicles, spacecraft instruments, spaceborne experiments, university/industry programs, spacecraft propulsion, life support systems, cryogenics, spacecraft power supplies, human factors engineering, spacecraft construction materials, aeroassist, aerobraking and aerothermodynamics.

Source record↗
NASA NTRS1988

Detection of parent molecules in the IR spectrum of P/Halley with the IKS-Vega spectrometer

The two spectroscopic channels of the IKS experiment on board the Vega probes were designed for the detection of emission bands of parent molecules and/or cometary dust, in the 2.5 to 5 micrometer range and the 6 to 12 micron range respectively. On Vega 1, the experiment worked successfully, and cometary spectra were recorded at distances from the comet nucleus ranging from about 250,000 to 40,000 km. The field of view was 1 deg and the spectral resolving power was about 50. On Vega 2, no result could be obtained due to a failure of the cryogenic system. The emission spectra obtained are briefly analyzed.

Encrenaz, Therese↗
NASA NTRS1990

Tank Pressure Control Experiment - A low-g mixing investigation

The Tank Pressure Control Experiment (TPCE) was conceived to meet the need for an aspect of cryogenic fluid management technology that is critical to several future national space missions: control of cryogenic storage tank pressures by active mixing. In-space testing is the only means of obtaining the fluid dynamic data necessary to develop and test predictive models of mixing. These models, when validated, will allow future cryogenic systems to be designed with more efficient and reliable pressure control systems. The objectives of the TPCE project are to characterize the fluid dynamics of jet-induced mixing in low gravity, evaluate the validity of empirical models and correlations, and provide data for use in developing and validating computational fluid dynamic models. This paper discusses prior studies of low-g mixing, the objectives and benefits of TPCE, the design and status of the payload, and preliminary results obtained from low-g aircraft testing.

Bentz, M. D.↗
NASA NTRS1991

Mechanically Oriented, Low-Curie-Temperature Materials

Proposed fabrication process produces permanent magnets of greater flux density, intended for use at temperatures far below room temperature. Such magnets parts of electrical motors and other electromechanical actuators operating in cryogenic systems. Performances of actuators increase with flux densities available from their magnets. Based on use of mechanical metallurgical techniques to make oriented magnets of Dy3Al2, because these techniques produce alignments above Curie temperature.

Boltich, Edward B.↗
NASA NTRS1991

Concentric Regenerative Sorption Compressor

Proposed sorption compressor for cryogenic system features four sorption units. Concentric sorption units alternately connected and disconnected via timed gas-gap thermal switches. During given half cycle, one of C/Kr sorption units operates on waste heat from one of PCO sorption units, which in turn operates partially on waste heat from other PCO sorption unit. Required power equals that of mechanical compressor. Vibrates less, and more reliable because it contains only few moving parts actuated relatively infrequently.

Jones, Jack A.↗
NASA NTRS1991

Sorption Compressor With Rotary Regenerator

Proposed two-stage sorption compressor for cryogenic system features rotary regenerator. At each stage, rotor interacts with stator to provide quadruple regeneration. Contains no valves, and only moving part is rotor, which turns very slowly. Features include less required power and greater reliability.

Jones, Jack A.↗
NASA NTRS1990

Aerospace applications of high temperature superconductivity

A review is presented of all the applications that are part of the NASA program to develop space technology capitalizing on the potential benefit of high temperature superconducting materials. The applications in three major areas are being pursued: sensors and cryogenic systems, space communications, and propulsion and power systems. This review places emphasis on space communications applications and the propulsion and power applications. It is concluded that the power and propulsion applications will eventually be limited by structural considerations rather than by the availability of suitable superconductors. A cursory examination of structural limitations implied by the virial theorem suggested that there is an upper limit to the size of high field magnetic systems that are feasible in space.

Connolly, D. J.↗
NASA NTRS1991

Technology needs for lunar and Mars space transfer systems

The determination of appropriate space transportation technologies and operating modes is discussed with respect to both lunar and Mars missions. Three levels of activity are set forth to examine the sensitivity of transportation preferences including 'minimum,' 'full science,' and 'industrialization and settlement' categories. High-thrust-profile missions for lunar and Mars transportation are considered in terms of their relative advantages, and transportation options are defined in terms of propulsion and braking technologies. Costs and life-cycle cost estimates are prepared for the transportation preferences by using a parametric cost model, and a return-on-investment summary is given. Major technological needs for the programs are listed and include storable propulsion systems; cryogenic engines and fluids management; aerobraking; and nuclear thermal, nuclear electric, electric, and solar electric propulsion technologies.

Woodcock, Gordon R.↗
NASA NTRS1992

An optical method for determining level in two-phase cryogenic fluids

A method was evaluated to measure the liquid-gas and the liquid-slush interfaces in two-phase cryogen systems using optical means. This method makes use of the attenuation of a directed light beam caused by the difference in the index of refraction between the solid particles and the surrounding liquid. Preliminary experimental results obtained in slush nitrogen are shown. The possibility of extending this technique to include a measure of solid fraction is also discussed.

Oberle, Lawrence G.↗