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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
All sourcesNASA NTRSDOE OSTI
NASA NTRS1982

Into Mesh Lubrication of Spur Gears with Arbitrary Offset Oil Jet. 2: for Jet Velocities Equal to or Greater than Great Velocity

An analysis was conducted for into mesh oil jet lubrication with an arbitrary offset and inclination angle from the pitch point for the case where the oil jet velocity is equal to or greater than gear pitch line velocity. Equations were developed for minimum and maximum oil jet impingement depth. The analysis also included the minimum oil jet velocity required to impinge on the gear or pinion and the optimum oil jet velocity required to obtain the best lubrication condition of maximum impingement depth and gear cooling. It was shown that the optimum oil jet velocity for best lubrication and cooling is when the oil jet velocity equals the gear pitch line velocity. When the oil jet velocity is slightly greater than the pitch line velocity the loaded side of the driven gear and the unloaded side of the pinion receive the best lubrication and cooling with slightly less impingement depth. As the jet velocity becomes much greater than the pitch line velocity the impingement depth is considerably reduced and may completely miss the pinion.

Akin, L. S.↗
NASA NTRS1976

Oil-air mist lubrication as an emergency system and as a primary lubrication system

The feasibility of an emergency aspirator once-through lubrication system was demonstrated as a viable survivability concept for Army helicopter mainshaft engine bearings for periods as long as 30 minutes. It was also shown in an experimental study using a 46-mm bore bearing test machine that an oil-air mist once-through system with auxiliary air cooling is an effective primary lubrication system at speeds up to 2,500,000 DN for extended operating periods of at least 50 hours.

Loomis, W. R.↗
NASA NTRS1982

Into Mesh Lubrication of Spur Gears with Arbitrary Offset Oil Jet. I: For Jet Velocity Less than or Equal to Gear Velocity

An analysis was conducted for into mesh oil jet lubrication with an arbitrary offset and inclination angle from the pitch point for the case where the oil jet velocity is equal to or less than pitch line velocity. The analysis includes the case for the oil jet offset from the pitch point in the direction of the pinion and where the oil jet is inclined to intersect the common pitch point. Equations were developed for the minimum oil jet velocity required to impinge on the pinion or gear and the optimum oil jet velocity to obtain the maximum impingement depth.

Akin, L. S.↗
NASA NTRS1983

Into mesh lubrication of spur gears with arbitrary offset oil jet. I - For jet velocity less than or equal to gear velocity

An analysis was conducted for into mesh oil jet lubrication with an arbitrary offset and inclination angle from the pitch point for the case where the oil jet velocity is equal to or less than pitch line velocity. The analysis includes the case for the oil jet offset from the pitch point in the direction of the pinion and where the oil jet is inclined to intersect the common pitch point. Equations were developed for the minimum oil jet velocity required to impinge on the pinion or gear and the optimum oil jet velocity to obtain the maximum impingement depth.

Akin, L. S.↗
NASA NTRS2010

An Assessment of Gas Foil Bearing Scalability and the Potential Benefits to Civilian Turbofan Engines

Over the past several years the term oil-free turbomachinery has been used to describe a rotor support system for high speed turbomachinery that does not require oil for lubrication, damping, or cooling. The foundation technology for oil-free turbomachinery is the compliant foil bearing. This technology can replace the conventional rolling element bearings found in current engines. Two major benefits are realized with this technology. The primary benefit is the elimination of the oil lubrication system, accessory gearbox, tower shaft, and one turbine frame. These components account for 8 to 13 percent of the turbofan engine weight. The second benefit that compliant foil bearings offer to turbofan engines is the capability to operate at higher rotational speeds and shaft diameters. While traditional rolling element bearings have diminished life, reliability, and load capacity with increasing speeds, the foil bearing has a load capacity proportional to speed. The traditional applications for foil bearings have been in small, lightweight machines. However, recent advancements in the design and manufacturing of foil bearings have increased their potential size. An analysis, grounded in experimentally proven operation, is performed to assess the scalability of the modern foil bearing. This analysis was coupled to the requirements of civilian turbofan engines. The application of the foil bearing to larger, high bypass ratio engines nominally at the 120 kN (approx.25000 lb) thrust class has been examined. The application of this advanced technology to this system was found to reduce mission fuel burn by 3.05 percent.

Bruckner, Robert J.↗
NASA NTRS1981

Dynamics of solid dispersions in oil during the lubrication of point of contacts. Part 2: Molybdenum disulfide

A Hertzian contact consisting of a steel ball in contact with a glass disk is lubricated with MoS2 dispersions and observed by optical microscopy at various slide/roll conditions. In general the behavior of MoS2 and graphite are similar. That is, the solids tend to enter the contact and form a film on the contacting surfaces whenever a rolling component of motion is used, but solid particles seldom enter the contact during pure sliding. The MoS2 has more pronounced plastic flow behavior than graphite. However, the polished steel ball is more readily scratched by MoS2 than by graphite. Under the conditions of these studies, lower friction and wear are observed with pure oil rather than with the dispersions. However under other conditions (such as different contact geometry or rougher surfaces) the solid lubricant dispersions might be beneficial.

Cusano, C.↗
DOE OSTI2021

Using Ionic Liquid Additive to Enhance Lubricating Performance for Low-Viscosity Engine Oil

Energy efficient lubricants are essential for sustainable transportation, and the trend is to develop and implement lower viscosity lubricants with more effective additives. Ionic liquids (ILs) have been reported as candidate additives with superior friction and wear reducing capabilities. Unlike most literature relying on bench-scale testing of simple oil–IL blends, this study produced low-viscosity (SAE 0W-12) fully formulated engine oils using a phosphonium-organophosphate IL as an antiwear additive and evaluated them in both bench-scale tribological testing and full-scale fired engine dynamometer testing. The experimental formulation containing a combination of ZDDP and IL outperformed the formulations using either ZDDP or IL alone, as well as a commercial SAE 0W-20 engine oil in terms of mitigating boundary friction, wear, and contact fatigue-induced micropitting. Furthermore, racing engine dynamometer tests demonstrated 3–4 °C lower oil temperature, 4–5 ft-lbs higher horsepower output, and up to 9.9% better fuel economy for the IL-containing SAE 0W-12 experimental oil compared with selected commercial SAE 5W-30 and 0W-20 engine oils.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS2002

A Systems Approach to the Solid Lubrication of Foil Air Bearings for Oil-Free Turbomachinery

Foil air bearings are self-acting hydrodynamic bearings which rely upon solid lubricants to reduce friction and minimize wear during sliding which occurs at start-up and shut-down when surface speeds are too low to allow the formation of a hydrodynamic air film. This solid lubrication is typically accomplished by coating the non-moving foil surface with a thin, soft polymeric film. The following paper introduces a systems approach in which the solid lubrication is provided by a combination of self lubricating shaft coatings coupled with various wear resistant and lubricating foil coatings. The use of multiple materials, each providing different functions is modeled after oil-lubricated hydrodynamic sleeve bearing technology which utilizes various coatings and surface treatments in conjunction with oil lubricants to achieve optimum performance. In this study, room temperature load capacity tests are performed on journal foil air bearings operating at 14,000 rpm. Different shaft and foil coating technologies such as plasma sprayed composites, ceramic, polymer and inorganic lubricant coatings are evaluated as foil bearing lubricants. The results indicate that bearing performance is improved through the individual use of the lubricants and treatments tested. Further, combining several solid lubricants together yielded synergistically better results than any material alone.

DellaCorte, Christopher↗
NASA NTRS1954

Drop Hammer Tests with Three Oleo Strut Models and Three Different Shock Strut Oils at Low Temperatures

Drop hammer tests with different shock strut models and shock strut oils were performed at temperatures ranging to -40 C. The various shock strut models do not differ essentially regarding their springing and damping properties at low temperatures; however, the influence of the different shock strut oils on the springing properties at low temperatures varies greatly.

LUBRICATING OILS, MINERAL↗
NASA NTRS1945

The Friction of Piston Rings

The coefficient of friction between piston ring and cylinder liner was measured in relation to gliding acceleration, pressure, temperature, quantity of oil and quality of oil. Comparing former lubrication-technical tests, conclusions were drawn as to the state of friction. The coefficients of friction as figured out according to the hydrodynamic theory were compared with those measured by tests. Special tests were made on "oiliness." The highest permissible pressure was measured and the ratio of pressure discussed.

LUBRICATING OILS - OILINESS↗
DOE OSTI2024

Reduced LCoE CSP Through Utilizing Process Gas Lubricated Bearings in Oil-Free Drivetrains

The GE Research team proposed to advance the TRL level of process lubricated gas bearings from TRL3 based on the DE-EE0007109 program to TRL5 addressing a critical risk item that radial gas bearings can provide satisfactory rotordynamic performance in supporting a representative rotor for sCO2 Power Cycles. The ability to apply process lubricated gas bearings can provide cost savings with reduction of the associated lube oil systems and an efficiency benefit worth 2% efficiency for the turbomachinery configuration first presented in DE-EE005804. The process lubricated gas bearings are enablers for advanced hermetically sealed configurations that have the potential for significant advancement in sCO2 Power Cycles for CSP applications including the 2% efficiency increase referred to above in addition to OPEX savings with no need to refill the CO2 valued at 60k USD/yr and cost reductions of 50 USD/kWe all leading to a potential 0.95¢/kWh reduction positively impacting CSP goals.

14 SOLAR ENERGY↗