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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 847 records · Page 47
All sourcesNASA NTRSDOE OSTI
NASA NTRS1985

Study of winglets applied to biplanes

This paper examines, both theoretically and experimentally, the possibility of improving the aerodynamic characteristics of a biplane configuration by adding winglets. Theoretical calculations show good agreement with experiment in predicting inviscid drag due to lift. Theoretical and experimental results indicate that the addition of winglets to an optimized biplane configuration can increase the ideal efficiency factor by up to 13 percent, as well as increasing the lift-curve slope and maximum lift coefficient. A theoretical analysis comparing the biplane with an optimized winglet to an equivalent monoplane indicates that the biplane has the potential for a 6.4-percent increase in L/D(max), and 13-percent increase in C(L) to the 3/2-power/C(D), the classical endurance parameter.

Gall, P. D.↗
NASA NTRS1985

Effects of exercise-heat acclimation on fluid, electrolyte, and endocrine responses during tilt and +Gz acceleration in women and men

Two aspects of prolonged endurance training were investigated: (1) the effects of exercise-heat acclimation (on a cycle ergometer at 40 C, 42 rh) on orthostatic tolerance (70 deg head-up tilt) and on a +Gz (head-to-foot) acceleration tolerance of male and female subjects; and (2) comparison of their fluid-electrolyte shifts and hormonal (plasma epinephdrine, norepinephrine, renin, and vasopressin) responses during tilting and centrifugation. The adaptive responses during the 12 d, 2-h acclimation did not alter acceleration tolerance of either men or women, or the women's tilt tolerance, but did increase men's tilt tolerance from 30.4 min before to 58.3 min after acclimation. The patterns of fluid, electrolyte, and protein shifts at tolerance in acceleration and tilting tests were virtually the same in men and women. On the other hand, the hormonal plasma epinephrine, norepinephrine, renin, and vasopressin resonses displayed different shift patterns during acceleration and tilting. It is concluded that the responses to tilting cannot be used to predict responses to acceleration. Future experiments for relating the orthostatic and the acceleration tolerances, and the practical questions of the training regimens for future astronauts are discussed.

Greenleaf, J. E.↗
NASA NTRS1984

Overview of NASA Lewis Research Center free-piston Stirling engine activities

A generic free-piston Stirling technology project is being conducted to develop technologies generic to both space power and terrestrial heat pump applications in a cooperative, cost-shared effort. The generic technology effort includes extensive parametric testing of a 1 kW free-piston Stirling engine (RE-1000), development of a free-piston Stirling performance computer code, design and fabrication under contract of a hydraulic output modification for RE-1000 engine tests, and a 1000-hour endurance test, under contract, of a 3 kWe free-piston Stirling/alternator engine. A newly initiated space power technology feasibility demonstration effort addresses the capability of scaling a free-piston Stirling/alternator system to about 25 kWe; developing thermodynamic cycle efficiency or equal to 70 percent of Carnot at temperature ratios in the order of 1.5 to 2.0; achieving a power conversion unit specific weight of 6 kg/kWe; operating with noncontacting gas bearings; and dynamically balancing the system. Planned engine and component design and test efforts are described.

Slaby, J. G.↗
NASA NTRS1986

Overview of free-piston Stirling SP-100 activities at the NASA Lewis Research Center

An overview of the National Aeronautics and Space Administration (NASA) Lewis Research Center (LeRC) SP-100 free-piston Stirling engine activities is presented. These activities are being conducted in support of the Department of Defense (DOD), Department of Energy (DOE), and NASA. The space-power technology effort, under SP-100, addresses the status of the 25 kWe Space Power Demonstrator Engine (SPDE). Another facet of the SP-100 project covers the status of an endurance test. Dynamic balancing of the SPDE engine is discussed along with a summary covering the parametric results of a study showing the relationship between power-converter specific weight and efficiency both as a function of Stirling engine heater to cooler temperature ratio. Design parameters and conceptual design features are presented for a 25 kWe, single-cylinder free-piston Stirling space-power converter. And finally, a description of a hydrodynamic gas bearing concept is presented.

Slaby, J. G.↗
NASA NTRS1986

Corrosion fatigue of 2219-T87 aluminum alloy

Corrosion fatigue studies were conducted on bare, chemical conversion coated, and anodized 2219-T87 aluminum alloy. These tests were performed using a rotating beam machine running at a velocity of 2500 rpm. The corrosive environments tested were distilled water, 100 ppm NaCl, and 3.5 percent NaCl. Results were compared to the endurance limit in air. An evaluation of the effect of protective coatings on corrosion fatigue was made by comparing the fatigue properties of specimens with coatings to those without.

Mcmillan, V. C.↗
NASA NTRS1984

Low-cost single-crystal turbine blades, volume 2

The overall objectives of Project 3 were to develop the exothermic casting process to produce uncooled single-crystal (SC) HP turbine blades in MAR-M 247 and higher strength derivative alloys and to validate the materials process and components through extensive mechanical property testing, rig testing, and 200 hours of endurance engine testing. These Program objectives were achieved. The exothermic casting process was successfully developed into a low-cost nonproperietary method for producing single-crystal castings. Single-crystal MAR-M 247 and two derivatives DS alloys developed during this project, NASAIR 100 and SC Alloy 3, were fully characterized through mechanical property testing. SC MAR-M 247 shows no significant improvement in strength over directionally solidified (DS) MAR-M 247, but the derivative alloys, NASAIR 100 and Alloy 3, show significant tensile and fatigue improvements. Firtree testing, holography, and strain-gauge rig testing were used to determine the effects of the anisotropic characteristics of single-crystal materials. No undesirable characteristics were found. In general, the single-crystal material behaved similarly to DS MAR-M 247. Two complete engine sets of SC HP turbine blades were cast using the exothermic casting process and fully machined. These blades were successfully engine-tested.

Strangman, T. E.↗
NASA NTRS1985

Physical, anthropometrical, and body composition characteristics of workers at Kennedy Space Center

At the Kennedy Space Center, workers are often exposed to cardiovascular and muscular stress in job-related activities which may require a high level of physical fitness in order to safely complete the work task. Similar tasks will be performed at other launch and landing facilities and in space for the Space Station. One such category includes workers who handle toxic propellants and must wear Self-Contained Atmospheric Protective Ensembles (SCAPE) that can weigh 56 lbs. with the air pack. These suits provide a significant physical challenge to many of the workers in terms of carrying this load while moving about and performing work. Furthermore, under some conditions, there is a significant thermal stress. The physical characteristics of these workers are, therefore, of consequence. The purpose of this study was to analyze the anthropometry, body composition, strength, power, endurance, flexibility, aerobic fitness, and blood variables of a representative sample of male KSC SCAPE workers and to compare them with characteristics of other male workers at KSC (total population N=110). Three separate comparisons were made.

Lasley, M. L.↗
NASA NTRS1986

Sputtered cadmium oxide as a surface pretreatment for graphite solid lubricant films

Sputtered films of cadmium oxide were applied to sand blasted AISI 440C HT stainless steel disks as a surface pretreatment for the application of rubbed graphite films. Mixtures of cadmium oxide and graphite were applied to the nonpretreated sandblasted metal and evaluated. The results were compared to graphite films applied to other commercially available surface pretreatments. It is found that sputtered CdO pretreated surfaces increase the endurance lives of the graphite films and decrease the counterface steady state wear rate of the pins almost an order of magnitude compared to commercially available pretreatments. The CdO additions in general improved the tribological properties of graphite. The greatest benefit occurred when it was applied to the substrate rather than mixing it with the graphite and that sputtered films of CdO perform much better than rubbed CdO films.

Fusaro, R. L.↗
NASA NTRS1985

Exercise hyperthermia as a factor limiting physical performance - Temperature effect on muscle metabolism

The effect of trunk cooling on the muscle contents of ATP, ADP, AMP, creatine phosphate (CrP), and creatine, as well as of glycogen, some glycolytic intermediates, pyruvate, and lactate were assessed in 11 fasted dogs exercised at 20 C on treadmill to exhaustion. Without cooling, dogs were able to run 57 min, and their rectal (Tre) and muscle (Tm) temperatures increased to 41.8 and 43.0 C, respectively. Cooling with ice packs prolonged the ability to run by 45 percent, and resulted in lower Tre (by 1.1 C) and Tm (by 1.2 C). Depletion of muscle content of total high-energy phosphates (ATP + CrP) and glycogen, and increases in contents of AMP, pyruvate, and lactate were lower in cooled dogs than in non-cooled dogs. The muscle content of lactiate correlated positively with TM. These results indicate that hypothermia accelerates glycolysis, and shifts the equilibrium between high- and low-energy phosphates in favor of the latter. The adverse effect of hypothermia on muscle metabolism may be relevant to the limitation of endurance.

Kozlowski, S.↗
NASA NTRS1985

Overview of the 1985 NASA Lewis Research Center SP-100 free-piston Stirling engine activities

This effort is keyed on the design, fabrication, assembly, and testing of a 25 kWe Stirling space-power technology-feasibility demonstrator engine. Another facet of the SP-100 project covers the status of a 9000-hr endurance test conducted on a 2 kWe free-piston Stirling/linear alternator system employing hydrostatic gas bearings. Dynamic balancing of the RE-1000 engine (a 1 kWe free-piston Stirling engine) using a passive dynamic absorber will be discussed along with the results of a parametric study showing the relationships of Stirling power converter specific weight and efficiency as functions of Stirling engine heater to cooler temperature ratio. Planned tests will be described covering a hydrodynamic gas bearing concept for potential SP-100 application.

Slaby, J. G.↗
NASA NTRS1986

Development of a reusable, flight-weight cryogenic foam insulation system

Attention is given to a light weight foam insulation system applicable to reusable cryogenic propellant tankage for hypersonic aircraft and space launch vehicles. The insulation system consists of nominally sized blocks of a high temperature-resistant polymethacrylimide foam that is wrapped with a vapor-impermeable membrane of Kapton-aluminum-Kapton laminate, which is adhesively bonded to the outer propellant tank wall. Test results are presented which indicate that this insulation system is capable of enduring a Mach 5 service environment without structural cracking, deterioration, or loss of performance.

Mcauliffe, P. S.↗
NASA NTRS1986

Water and electrolytes

It has been found that the performance of the strongest and fittest people will deteriorate rapidly with dehydration. The present paper is concerned with the anatomy of the fluid spaces in the body, taking into account also the fluid shifts and losses during exercise and their effects on performance. Total body water is arbitrarily divided into that contained within cells (cellular) and that located outside the cells (extracellular). The anatomy of body fluid compartments is considered along with the effects of exercise on body water, fluid shifts with exercise, the consequences of sweating, dehydration and exercise, heat acclimatization and endurance training, the adverse effects of dehydration, thirst and drinking during exercise, stimuli for drinking, and water, electrolyte, and carbohydrate replacement during exercise. It is found that the deterioration of physical exercise performance due to dehydration begins when body weight decreases by about 1 percent.

Greenleaf, J. E.↗
NASA NTRS1986

Lubricant and additive effects on spur gear fatigue life

Spur gear endurance tests were conducted with six lubricants using a single lot of consumable-electrode vacuum melted (CVM) AISI 9310 spur gears. The sixth lubricants was divided into four batches each of which had a different additive content. Lubricant tested with a phosphorus-type load carrying additive showed a statistically significant improvement in life over lubricants without this type of additive. The presence of sulfur type antiwear additives in the lubricant did not appear to affect the surface fatigue life of the gears. No statistical difference in life was produced with those lubricants of different base stocks but with similar viscosity, pressure-viscosity coefficients and antiwar additives. Gears tested with a 0.1 wt pct sulfur and 0.1 wt pct phosphorus EP additives in the lubricant had reactive films that were 200 to 400 (0.8 to 1.6 microns) thick.

Townsend, D. P.↗
NASA NTRS1986

Towards an optimised sputtered MoS2 lubricant film

It is shown that the tribological quality of MoS2 lubricant films formed by magnetron sputtering is determined by the choice of sputtering conditions. By selecting the appropriate conditions, films of extremely high lubricity and endurance (in vacuum), which are well suited to many space applications, are obtained. Such MoS2 films, when applied to precision ball hearings, give rise to the lowest torques (for the given test conditions) yet seen in our laboratory. While a remarkably good performance is obtained in vacuum, tests in air show a marked deterioration in lubricating qualities. It is demonstrated that this is attributable to the adsorption of water vapor on MoS2 surfaces and that the degree of deterioration is related to the partial pressure of water vapor present. Analysis of results indicates that the factors relevant to obtaining optimum films are deposition rate and film composition.

Roberts, E. W.↗
NASA NTRS1986

Long-term module testing at Wyle Laboratories

Results are presented for a current set of accelerated long-term endurance tests on crystalline silicon module of various constructions. Cell materials include single crystal, semicrystal, EFG ribbon, and dendritic web ribbon. The latest data set is for the equivalent of 20-year life and showed satisfactory performance.

Otth, D. H.↗
NASA NTRS1986

Oceanographic measurement capabilities of the NASA P-3 aircraft

Instrumentation on NASA P3 aircraft available to provide ground truth for ERS-1 is described. The wave sensors include the 36 GHz Surface Contour Radar (SCR), the Ku-band Radar Ocean Wave Spectrometer (ROWS), and the Airborne Oceanographic Lidar. The other sensors include a C-band scatterometer, video camera, radiation thermometer, and AXRTs. The SCR and ROWS directional spectrum measurements are discussed. When planning for an underflight mission, the limited endurance of the aircraft (6 hr) and flight cost (2.7 K$/hr) must be considered. The advantage of the redundancy afforded by the several wave instruments is another important consideration.

Mollo-Christensen, Erik↗
NASA NTRS1987

Ion plated gold films: Properties, tribological behavior and performance

The glow discharge energizing favorably modifies and controls the coating/substrate adherence and the nucleation and growth sequence of ion plated gold films. As a result the adherence, coherence, internal stresses, and morphology of the films are significantly improved. Gold ion plated films because of their graded coating/substrate interface and fine uniform densely packed microstructure not only improve the tribological properties but also induce a surface strengthening effect which improves the mechanical properties such as yield, tensile, and fatigue strength. Consequently significant improvements in the tribological performance of ion plated gold films as compared to vapor deposited gold films are shown in terms of decreased friction/wear and prolonged endurance life.

Spalvins, Talivaldis↗
NASA NTRS1987

Effects of surface removal on rolling-element fatigue

The Lundberg-Palmgren equation was modified to show the effect on rolling-element fatigue life of removing by grinding a portion of the stressed volume of the raceways of a rolling-element bearing. Results of this analysis show that depending on the amount of material removed, and depending on the initial running time of the bearing when material removal occurs, the 10-percent life of the reground bearings ranges from 74 to 100 percent of the 10-percent life of a brand new bearing. Three bearing types were selected for testing. A total of 250 bearings were reground. Of this matter, 30 bearings from each type were endurance tested to 1600 hr. No bearing failure occurred related to material removal. Two bearing failures occurred due to defective rolling elements and were typical of those which may occur in new bearings.

Zaretsky, Erwin V.↗