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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 271 records · Page 15
All sourcesNASA NTRSDOE OSTI
NASA NTRS1975

Solid state electro-optic color filter and iris

A pair of solid state electro-optic filters (SSEF) in a binocular holder were designed and fabricated for evaluation of field sequential stereo TV applications. The electronic circuitry for use with the stereo goggles was designed and fabricated, requiring only an external video input. A polarizing screen suitable for attachment to various size TV monitors for use in conjunction with the stereo goggles was designed and fabricated. An improved engineering model 2 filter was fabricated using the bonded holder technique developed previously and integrated to a GCTA color TV camera. An engineering model color filter was fabricated and assembled using PLZT control elements. In addition, a ruggedized holder assembly was designed, fabricated and tested. This assembly provides electrical contacts, high voltage protection, and support for the fragile PLZT disk, and also permits mounting and optical alignment of the associated polarizers.

Source record↗
NASA NTRS1985

Tapered Ring Seal

Centering force maximized by decreased seal clearance in flow direction. Increased centering force prevents contact between seal and shaft, eliminating seal wear. Ring seals used to restrict fluid leakage between rotating shaft and nonrotating housing. Seal used in Space Shuttle main engine oxygen pump.

Fleming, D. P.↗
NASA NTRS1996

Brush Seals for Cryogenic Applications: Performance, Stage Effects, and Preliminary Wear Results in LN2 and LH2

Brush seals are compliant contacting seals and have significantly lower leakage than labyrinth seals in gas turbine applications. Their long life and low leakage make them candidates for use in rocket engine turbopumps. Brush seals, 50.8 mm (2 in.) in diameter with a nominal 127-micron (0.005-in.) radial interference, were tested in liquid nitrogen (LN2) and liquid hydrogen (LH2) at shaft speeds up to 35,000 and 65,000 rpm, respectively, and at pressure drops up to 1.21 MPa (175 psid) per brush. A labyrinth seal was also tested in liquid nitrogen to provide a baseline. The LN2 leakage rate of a single brush seal with an initial radial shaft interference of 127 micron (0.005 in.) measured one-half to one-third the leakage rate of a 12-tooth labyrinth seal with a radial clearance of 127 micron (0.005 in.). Two brushes spaced 7.21 micron (0.248 in.) apart leaked about one-half as much as a single brush, and two brushes tightly packed together leaked about three-fourths as much as a single brush. The maximum measured groove depth on the Inconel 718 rotor with a surface finish of 0.81 micron (32 microinch) was 25 micron (0.0010 in.) after 4.3 hr of shaft rotation in liquid nitrogen. The Haynes-25 bristles wore approximately 25 to 76 micron (0.001 to 0.003 in.) under the same conditions. Wear results in liquid hydrogen were significantly different. In liquid hydrogen the rotor did not wear, but the bristle material transferred onto the rotor and the initial 127 micron (0.005 in.) radial interference was consumed. Relatively high leakage rates were measured in liquid hydrogen. More testing is required to verify the leakage performance, to validate and calibrate analysis techniques, and to determine the wear mechanisms. Performance, staging effects, and preliminary wear results are presented.

Proctor, Margaret P.↗
NASA NTRS2018

Cumulative Distribution of Ballistic Impact Failures of Common Twisted-Pair Data Cables at Orbital Speeds

Data wire cable runs are a significant presence on the exterior of the International Space Station (ISS), and continued ISS mission support requires detailed assessment of cables due to micrometeoroid and orbit debris (MMOD) impact. These data wire cables are twisted-pair cables consisting of two 22AWG stranded conductors and fillers inside a tight fitting braided copper shield. The copper shield and its contents are covered with a jacket that has a nominal outer diameter of 3.76 mm and beta-cloth tape. The ISS engineering community has identified two loss-of-function mechanisms for these cables: open circuits due to severed conductors within the cable, and short circuits due to contact between conductors or grounded components. As these data cables are low power systems, short circuits are not expected to burn away the contact, so both open and short circuits are considered permanent loss-of-function for the cable. A total of ninety-seven impact experiments have been performed into these cables to develop a statistical model for the failure of these cables to be used in reliability studies. The experimental work has yielded cumulative distribution functions for these cables for steel and aluminum components of the orbital debris environment at representative speeds and impact obliquities.

Miller, Joshua E.↗
NASA NTRS1990

Tribological Properties Of Ceramics

Report reviews adhesion, friction, and micromechanical properties of ceramics - properties increasingly important as more ceramic materials used in bearings, seals, and gears in advanced engines and in cutting tools and extrusion dies. Report considers effects of contaminating surface films, temperature, and chemical interactions. Examines ceramics, in both monolithic and coating form, in contact with themselves, with other harder materials, and with metals.

Miyoshi, Kazuhisa↗
NASA NTRS2001

Second Generation RLV Program

During the time period covered by this report, SAIC: 1) Continued to develop and assess processes and approaches that can be applied to Second Generation Reuseable Launch Vehicles (RLV) technologies prioritization. An approach based on the use of analytic Saaty scale functions has been defined and is being investigated. 2) Planned and facilitated technologies prioritization workshops, supported development of systems program algorithms based on the concept of influence diagramming, and assessment of analogies between aircraft and space systems developments. 3) Video interviews held with X-37 personnel at Dryden. The CD-ROM is being concluded and a near-final review disc is expected soon. 4) CD-ROMS were produced by Engineered Multimedia, Inc. (EMI) under subcontract to SAIC. These two CD-ROM products, "Microgravity" and "New Horizons", were delivered to MSFS technical representatives at a briefing at SAID on January 18, 2001. 5) Presentation brochure, "Aviation/Space Analog Team Interim Report" was provided to Space Propulsion Synergy Team (SPST) members and to NASA personnel. Wrap-up of effort will be a mid-April briefing to both MSFC and the full SPST membership. Support to Phase 2 of CCPD ends 3/31/01. Phase 3 continuation effort planned with emphasis on technical info content. 6) Recommended that eliminating the B-52 flights of the X-37 in favor of alternate approached be evaluated. Discovered that a required change to the thruster valves of the X-37 had not been made. Repair work continues on the lower fuselage section of the X-37, in the areas that experienced core collapse. The currently catalogued potential weight increases and decreases are about equal, but this does not include the impact of the cable weight underestimate reported earlier. The CFD for RCS testing correlates well with the wind tunnel data. 7) The Level IV CCB approved SCN-4 to the MC-1 Engine SPecification. Approved changes have been incorporated into the specification, and Revision D has been released to the Repository. Billy Gonterman, SAIC, traveled to SSC to perform a five-day readiness assessment on the progress of facilities activation. Implemented modifications to the MC-1 Engine TPA Component Database. 8) Replaced 25 Combined-Cycle Propulsion Database (CCPD) documents; modified the low-on screen to include a direct email link for user contact; prepared a summary presentation of current and proposed tasks.

Laue, Jay↗
NASA NTRS1996

Magnetic Bearing

AVCON, Inc. produces advanced magnetic bearing systems for industrial use, offering a unique technological approach based on contract work done at Marshall Space Flight Center and Lewis Research Center. Designed for the turbopump of the Space Shuttle main engine, they are now used in applications such as electric power generation, petroleum refining, machine tool operation and natural gas pipelines. Magnetic bearings support moving machinery without physical contact; AVCON's homopolar approach is a hybrid of permanent and electromagnets which are one-third the weight, smaller and more power- efficient than previous magnetic bearings.

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NASA NTRS2005

Prediction of Fretting Crack Location and Orientation in a Single Crystal Nickel Alloy

Fretting is a structural damage mechanism arising between two nominally clamped surfaces subjected to an oscillatory loading. A critical location for fretting induced damage has been identified at the blade/disk and blade/damper interfaces of gas turbine engine turbomachinery and space propulsion components. The high- temperature, high-frequency loading environment seen by these components lead to severe stress gradients at the edge-of-contact that could potentially foster crack growth leading to component failure. These contact stresses drive crack nucleation in fretting and are very sensitive to the geometry of the contacting bodies, the contact loads, materials, temperature, and contact surface tribology (friction). Recently, a high-frequency, high-temperature load frame has been designed for experimentally investigating fretting damage of single crystal nickel materials employed in aircraft and spacecraft turbomachinery. A modeling method for characterizing the fretting stresses of the spherical fretting contact stress behavior in this experiment is developed and described. The calculated fretting stresses for a series of experiments are then correlated to the observed fretting damage. Results show that knowledge of the normal stresses and resolved shear stresses on each crystal plane can aid in predicting crack locations and orientations.

Matlik, J. F.↗
NASA NTRS1980

Evaluation of axial lock-up of space shuttle main engine bearings from high pressure oxygen turbopump

The mainshaft support bearings of long life turbopumps for use on the space shuttle were evaluated to determine possible causes of failure. Specific aspects examined include the sensitivity of 15 degree versus 25 degree contact angle bearings with regard to heat damage and thermal runaway, the L/D aspects of the turbine end bearing pair with regard to hang-up due to cocking, the hang-up required to support a 44.5 KN axial load without cartridge slipping, the outer race growth as a result of a 44.5 KN axial load, and bearing torque as a function of axial load. Results indicate that hang-up of the cartridge due to bearing heating is a serious problem especially if poor lubrication of the bearing occurs and that race growth due to axial load can contribute to cartridge lock-up. The experimental evaluation of bearing performance under axial loads indicates that the bearing torque is a strong function of surface lubrication.

Kannel, J. W.↗
NASA NTRS1972

Diffusion bonding and its application to manufacturing

In its simplest form diffusion bonding is accomplished by placing clean metal surfaces together under a sufficient load and heating. The natural interatomic attractive force between atoms transforms the interface into a natural grain boundary. Therefore, in principle, the properties of the bond area are identical to those of the parent metal. Other advantages of diffusion bonding over conventional methods of bonding include freedom from residual stresses, excessive deformation, foreign metals, or changed crystal structures. Stainless steels, nickel-base superalloys, and aluminum alloys have all been successfully joined. Complex hardware, including integrated flueric devices, jet engine servovalves, and porous woven structures have been fabricated. The processing involved is discussed, along with such theoretical considerations as the role of metal surfaces, the formation of metal contact junctions, and the mechanisms of material transport in diffusion bonding.

Spurgeon, W. M.↗
NASA NTRS1986

Evaluation of transfer films of Salox M on 440C for HPOTP bearing cage applications, task 119

The objective of the task was to evaluate the suitability of a bronze-filled polytetra fluoroethylene (Salox M) as the cage material in Space Shuttle Main Engine (SSME) high pressure oxygen turbo pump (HPOTP) bearings. The role of the cage pocket material will be to provide a transferred lubricating interface at the ball-race contact region. A series of experiments was conducted which involved block-on-ring tests (the block was the polytetrafluoroethylene (PTFE) -filled material and the ring was through-hardened 440C steel) and high speed traction tests of two 440C disks with one disk rubbed with a PTFE block to generate a transfer film. Measurements included post test visual observations of the condition of the 440C, wear rate measurements of the blocks, and traction measurements between the disks. It was observed that both Salox M and glass-filled PTFE (Armalon) transferred PTFE to 440C at cryogenic temperatures. Bronze is also transferred to uncoated 440C from the Salox M. At room temperature no PTFE transfer was observed in the high speed disk tests due to severe frictional heating, although bronze transfer still occurred with the bronze-PTFE Salox M material. Since the bearing will operate at cryogenic temperature, transfer films are very probable. Salox M wore slightly, although probably tolerably, more than glass-filled PTFE against 440C. However, Salox M is clearly less abrasive to 440C than is the glass-filled material. When the surface layer of PTFE is depleted from the glass-filled material, the glass fibers tend to seriously abrade the steel. This problem does not occur with Salox M. The surface roughness studies indicate that smooth balls are quite reasonable for transfer films. No significant difference in wear rates of the candidate cage materials was observed when the 440C surface finish was increased from 0.025 micron to 0.1 micron cla. At higher levels of roughness, the wear rate increased. Two surface coatings (MoS2 and TiN) were tested. The surface coatings tended to reduce the Salox M wear rate and reduce bronze transfer. PTFE transfer at cryogenic temperatures still occurred with the surface coatings. Two cage design concepts are presented utilizing Salox M material. One design involves a metal-reinforced Salox M cage, while the second design uses Salox M inserts in a metal structure.

Barber, S. A.↗
NASA NTRS1993

Brush seals for cryogenic applications

Brush seals are compliant, contacting seals and have significantly lower leakage than labyrinth seals in gas turbine applications. Their characteristics of long life and low leakage make them candidates for use in rocket engine turbopumps. Two-inch diameter brush seals with a nominal 0.005 inch radial interference were tested in liquid nitrogen at shaft speeds up to 35,000 rpm and pressure drops up to 175 psid per seal. A labyrinth seal was also tested to provide a baseline. Performance, staging effects, and wear results are presented.

Proctor, Margaret P.↗
NASA NTRS1999

Simultaneous Optical Measurements of Axial and Tangential Steady-State Blade Deflections

Currently, the majority of fiber-optic blade instrumentation is being designed and manufactured by aircraft-engine companies for their own use. The most commonly employed probe for optical blade deflection measurements is the spot probe. One of its characteristics is that the incident spot on a blade is not fixed relative to the blade, but changes depending on the blade deformation associated with centrifugal and aerodynamic loading. While there are geometrically more complicated optical probe designs in use by different engine companies, this paper offers an alternate solution derived from a probe-mount design feature that allows one to change the probe axial position until the incident spot contacts either a leading or a trailing edge. By tracing the axial position of either blade edge one is essentially extending the deflection measurement to two dimensions, axial and tangential. The blade deflection measurements were obtained during a wind tunnel test of a fan prototype.

Kurkov, Anatole P.↗
NASA NTRS2005

High-Frequency, High-Temperature Fretting Experiments

Fretting is a structural damage mechanism observed when two nominally clamped surfaces are subjected to an oscillatory loading. A critical location for fretting induced damage has been identified at the blade/disk and blade/damper interfaces of gas turbine engine turbomachinery and space propulsion components. The high-temperature, high-frequency loading environment seen by these components lead to severe stress gradients at the edge-of-contact. These contact stresses drive crack nucleation and propagation in fretting and are very sensitive to the geometry of the contacting bodies, the contact loads, materials, temperature, and contact surface tribology (friction). To diagnose the threat that small and relatively undetectable fretting cracks pose to damage tolerance and structural integrity of in-service components, the objective of this work is to develop a well-characterized experimental fretting rig capable of investigating fretting behavior of advanced aerospace alloys subjected to load and temperature conditions representative of such turbomachinery components.

Matlik, J. F.↗
NASA NTRS2007

Hand-Held Instrument Fights Acne, Tops Over-the-Counter Market

Tyrell Inc., a Houston-based medical technologies company, was able to access engineering support in redesigning a heating element for a hand-held acne-fighting device through SATOP, NASA's Space Alliance Technology Outreach Program. SATOP put Tyrell in contact with The Boeing Company, which assessed the design and made several major contributions. The product, named Zeno, is now the highest selling over-the-counter medical device for the treatment of acne, and in 2006, Zeno was named the "SATOP Texas, Success Story of the Year." Zeno employs proprietary ClearPoint technology to provide relief of mild to moderate inflammatory acne by delivering a precisely controlled low-level dosage of heat to the blemish, causing the bacteria at the root of more than 90 percent of acne to self-destruct. Within its first year on the market, Zeno was cited by various publications for several awards, including Allure's 2005 "Best of Beauty," Marie Claire's "10 Best Gadgets for Girls," and Popular Science's 2005 "Best of What's New." A variation of the Zeno for use in treating herpetic lesions such as cold sores, by killing the virus that causes them, is currently undergoing FDA trials.

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NASA NTRS2012

Non-intrusive Shock Measurements Using Laser Doppler Vibrometers

Stud mount accelerometers are widely used by the aerospace industry to measure shock environments during hardware qualification. The commonly used contact-based sensors, however, interfere with the shock waves and distort the acquired signature, which is a concern not actively discussed in the community. To alleviate these interference issues, engineers at the Jet Propulsion Laboratory are investigating the use of non-intrusive sensors, specifically Laser Doppler Vibrometers, as alternatives to the stud mounted accelerometers. This paper will describe shock simulation tests completed at the Jet Propulsion Laboratory, compare the measurements from stud mounted accelerometers and Laser Doppler Vibrometers, and discuss the advantages and disadvantages of introducing Laser Doppler Vibrometers as alternative sensors for measuring shock environments.

shock testing↗
NASA NTRS2024

NASA's Armstrong Flight Research Center Research, Technology, and Engineering Report

As we support NASA’s aerospace research and development missions, we strive to ensure that the public is aware of our advancements. This report is a compilation of the wide range of work being conducted at NASA Armstrong, along with contact information for the associated technologists responsible for each effort. We encourage you to reach out to these researchers for more information or to discuss collaboration ideas.

David F Voracek↗