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  • Cell & Developmental Biology  (942)
  • AIRCRAFT PROPULSION AND POWER
  • 1995-1999
  • 1985-1989
  • 1980-1984  (807)
  • 1975-1979  (587)
  • 1940-1944
  • 1984  (807)
  • 1977  (587)
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  • 1995-1999
  • 1985-1989
  • 1980-1984  (807)
  • 1975-1979  (587)
  • 1940-1944
Year
  • 1
    Publication Date: 2006-04-09
    Description: For several years the Department of Defense has been sponsoring fuel accommodation investigations with gas turbine engine manufacturers and supporting organizations to quantify the effect of changes in fuel properties and characteristics on the operation and performance of military engine components and systems. Inasmuch as there are many differences in hardware between the operational engines in the military inventories, due to differences in design philosophy and requirements, efforts were initially expended to acquire fuel effects data from rigs simulating the hot sections of these different engines. Correlations were then sought using the data acquired to produce more general, generic relationships that could be applied to all military gas turbine engines regardless of their origin. Finally, models could be developed from these correlations that could predict the effect of fuel property changes on current and future engines. This presentation describes some of the work performed by Pratt and Whitney Aircraft, under Naval Air Propulsion Center sponsorship, to determine the effect of fuel properties on the hot section and fuel system of the Navy's TF30-P-414 gas turbine engine.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Lewis Research Center Assessment of Alternative Aircraft Fuels; p 63-72
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  • 2
    Publication Date: 2006-04-09
    Description: In an attempt to rigorously study the fuel chemical property influence, UTRC (United Technologies Research Center) (under contract to NASA Lewis Research Center) has conducted an experimental program using 25 test fuels. The burner was a 12.7 cm dia cylindrical device consisting of six sheet metal louvers. A single pressure atomizing injector and air swirler were centrally mounted with the conical dome. Fuel physical properties were de-emphasized by using fuel injectors which produced highly atomized, and hence rapidly vaporizing sprays. A substantial fuel spray characterization effort was conducted to allow selection of nozzles which assured that such sprays were achieved for all fuels. The fuels were specified to cover the following wide ranges of chemical properties: hydrogen, 9.1 to 15 (wt) pct; total aromatics, 0 to 100 (vol) pct; and naphthalene, 0 to 30 (vol) pct. They included standard fuel (e.g., Jet A, JP4), specialty products (e.g., decalin, xylene tower bottoms) and special fuel blends. Included in this latter group were six, 4-component blends prepared to achieve parametric variations in fuel hydrogen, total aromatics and naphthalene contents.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Lewis Research Center Assessment of Alternative Aircraft Fuels; p 31-46
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  • 3
    Publication Date: 2006-02-14
    Description: Starting with the NASA-sponsored STAEBL program, optimization methods based primarily upon the versatile program COPES/CONMIN were introduced over the past few years to a broad spectrum of engineering problems in structural optimization, engine design, engine test, and more recently, manufacturing processes. By automating design and testing processes, many repetitive and costly trade-off studies have been replaced by optimization procedures. Rather than taking engineers and designers out of the loop, optimization has, in fact, put them more in control by providing sophisticated search techniques. The ultimate decision whether to accept or reject an optimal feasible design still rests with the analyst. Feedback obtained from this decision process has been invaluable since it can be incorporated into the optimization procedure to make it more intelligent. On several occasions, optimization procedures have produced novel designs, such as the nonsymmetric placement of rotor case stiffener rings, not anticipated by engineering designers. In another case, a particularly difficult resonance contraint could not be satisfied using hand iterations for a compressor blade, when the STAEBL program was applied to the problem, a feasible solution was obtained in just two iterations.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Langley Research Center Recent Experiences in Multidisciplinary Analysis and Optimization, Part 2; 18 p
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  • 4
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    In:  CASI
    Publication Date: 2006-04-09
    Description: The study performed in Phase 1 of this program applies only to a T700/CT7 engine family type combustor functioning in the engine as defined and does not necessarily apply to other cycles or combustors of differing stoichiometry. The study was not extended to any of the fuel delivery accessories such as pumps or control systems, nor was there any investigation of potential systems problems which might arise as a consequence of abnormal properties such as density which might affect delivery schedules or aromatics content which might affect fuel system seals. The T700/CT7 engine is a front drive turboshaft or turboprop engine in the 1500-1800 shp (1120-1340 kW) class as currently configured with highpower core flows of about 10 lb/sec (4.5 kg/sec). It employs a straight-through annular combustion system less than 5 in. (12.5 cm) in length utilizing a machined ring film cooled construction and twelve low-pressure air blast fuel injectors. Commercial and Naval versions employ two 0.5 Joule capacitive discharge surface gap ignitors.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Lewis Research Center Assessment of Alternative Aircraft Fuels; p 89-98
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  • 5
    Publication Date: 2006-04-09
    Description: Since the early 1970s, the cost and availability of aircraft fuel have changed drastically. These problems prompted a program to evaluate the effects of broadened specification fuels on current and future aircraft engine combustors employed by the USAF. Phase 1 of this program was to test a set of fuels having a broad range of chemical and physical properties in a select group of gas turbine engine combustors currently in use by the USAF. The fuels ranged from JP4 to Diesel Fuel number two (DF2) with hydrogen content ranging from 14.5 percent down to 12 percent by weight, density ranging from 752 kg/sq m to 837 kg/sq m, and viscosity ranging from 0.830 sq mm/s to 3.245 sq mm/s. In addition, there was a broad range of aromatic content and physical properties attained by using Gulf Mineral Seal Oil, Xylene Bottoms, and 2040 Solvent as blending agents in JP4, JP5, JP8, and DF2. The objective of Phase 2 was to develop simple correlations and models of fuel effects on combustor performance and durability. The major variables of concern were fuel chemical and physical properties, combustor design factors, and combustor operating conditions.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Lewis Research Center Assessment of Alternative Aircraft Fuels; p 47-62
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  • 6
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    In:  CASI
    Publication Date: 2006-01-16
    Description: Thrust and weight requirements of aircraft engines in general are discussed. The characteristics and operating principles of various types of air breathing and rocket engines are described.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Soviet Aircraft and Rockets (NASA-TT-F-770); p 81-139
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  • 7
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    In:  Other Sources
    Publication Date: 2011-08-18
    Description: Previously cited in issue 05, p. 656, Accession no. A82-16909
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Journal of Guidance, Control, and Dynamics (ISSN 0731-5090); 7; 183-189
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  • 8
    Publication Date: 2011-08-19
    Description: Experimental results are presented for the case of titanium blade tip specimens of various geometrical configurations rubbing at 100 m/s against specimens of nickel-chromium sintered powder metal seal material, the latter being fed toward the rotating blades at an incursion rate of 0.0254 mm/s. Blade tips in the form of orthogonal cutting tools with about 85 deg negative rake angles exhibited desirable abrading capabilities, as measured by the tear-free appearance of the grooves they generated in the seal material, little wear of blade tips, low forces of interaction and low seal densification. Similar results have been obtained for blade specimens with tips of small radius of curvature, as well as for square-ended and slanted blade tips that are plasma-sprayed with abrasive particles. The relationship between the size of these particles and their abrading effectiveness is considered.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: ASME, Transactions, Journal of Tribology (ISSN 0742-4787); 106; 527-533
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  • 9
    Publication Date: 2011-08-17
    Description: A scramjet/airframe integration program and a technique for simulating thermally perfect scramjet exhaust flows (freon/argon gas blends) is studied to extend the technique to more complicated flows approaching the actual exhaust flow in complexity. The state of the flow and the accuracy of the substitute gas simulation are analyzed in the case of a shock discontinuity present. Findings are: scramjet exhaust flow is essentially frozen throughout the expansion at Mach 6 and Mach 8; flow behind moderate shocks remains frozen; the technique can accurately track static distributions in scramjet exhaust flows (shocked or unshocked).
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Journal of Aircraft; 14; Sept
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  • 10
    Publication Date: 2011-08-18
    Description: Previously cited in issue 10, p. 1378, Accession no. A83-25957
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Journal of Aircraft (ISSN 0021-8669); 21; 135-142
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  • 11
    Publication Date: 2016-06-07
    Description: The trajectory, penetration and mixing efficiency of lateral air jet injection into typical combustor flowfields in the absence of combustion were investigated so as to characterize the time-mean and turbulence flowfield for a variety of configurations and input parameters, recommend appropriate turbulence model advances, and implement and exhibit results of flowfield predictions. A combined experimental and theoretical approach was followed, in a modified version of the test facility, equipped initially with one and two lateral jets, located one test-section downstream of the inlet.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Lewis Research Center Turbine Engine Hot Section Technology, 1984; 11 p
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  • 12
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    In:  CASI
    Publication Date: 2016-06-07
    Description: The accuracy and utility of current aerothermal models for gas turbine combustors must be improved. Three areas of concern are identified: improved numerical methods for turbulent viscous recirculating flows; flow interaction; and fuel injector-air swirl characterization. Progress in each area is summarized.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Turbine Engine Hot Section Technology, 1984; 4 p
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  • 13
    Publication Date: 2016-06-07
    Description: The Structural Tailoring of Engine Blades (STAEBL) program was initiated at NASA Lewis Research Center in 1980 to introduce optimal structural tailoring into the design process for aircraft gas turbine engine blades. The standard procedure for blade design is highly iterative with the engineer directly providing most of the decisions that control the design process. The goal of the STAEBL program has been to develop an automated approach to generate structurally optimal blade designs. The program has evolved as a three-phase effort with the developmental work being performed contractually by Pratt & Whitney Aircraft. Phase 1 was intended as a proof of concept in which two fan blades were structurally tailored to meet a full set of structural design constraints while minimizing DOC+I (direct operating cost plus interest) for a representative aircraft. This phase was successfully completed and was reported in reference 1 and 2. Phase 2 has recently been completed and is the basis for this discussion. During this phase, three tasks were accomplished: (1) a nonproprietary structural tailoring computer code was developed; (2) a dedicated approximate finite-element analysis was developed; and (3) an approximate large-deflection analysis was developed to assess local foreign object damage. Phase 3 is just beginning and is designed to incorporated aerodynamic analyses directly into the structural tailoring system in order to relax current geometric constraints.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Langley Research Center Recent Experiences in Multidisciplinary Analysis and Optimization, Part 1; 13 p
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  • 14
    Publication Date: 2016-06-07
    Description: The Liner Environment Effects Study Program is aimed at establishing a broad heat transfer data base under controlled experimental conditions by quantifying the effects of the combustion system conditions on the combustor liner thermal loading and on the flame radiation characteristics. Five liner concepts spanning the spectrum of liner design technology from the very simple to the most advanced concepts are investigated. These concepts comprise an uncooled liner, a conventional film cooled liner, an impingement/film cooled liner, a laser drilled liner approaching the concept of a porous wall, and a siliconized silicon carbide ceramic liner. Effect of fuel type is covered by using fuels containing 11.8, 12.8, and 14% hydrogen. Tests at 100, 200, and 300 psia provide a basis for evaluating the effect of pressure on the heat transfer. The effects of the atomization quality and spray characteristics are examined by varying the fuel spray Sauter mean diameter and the spray angle. Additional varied parameters include reference velocity, a wide range of equivalence ratio, cooling flow rate, coolant temperature and the velocity of the coolant stream on the backside of the liner.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Lewis Research Center Combust. Fundamentals Res.; p 275-284
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  • 15
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    Publication Date: 2011-08-17
    Description: The status of technologies for jet-lift V/STOL aircraft is examined, and a critical review of the performance of jet-lift VTOL aircraft built to date is made. Most jet-lift aircraft have suffered from adverse propulsion-induced effects during takeoff and landing. Flight dynamics of jet-lift aircraft have suffered from shortcomings in static and dynamic stability, control characteristics, and flight path control. Some of the main problems to be considered during the selection of a propulsion system arrangement for a V/STOL fighter are discussed. At present, experimental and analytical data on supersonic V/STOL configurations are insufficient to permit evaluating propulsion system arrangements.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Astronautics and Aeronautics; 15; Dec. 197
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  • 16
    Publication Date: 2012-05-19
    Description: An experimental investigation was performed to determine the effect of endwall cooling on the secondary flow behavior and the aerodynamic performance of a coreturbine stator vane. The investigation was conducted in a cold-air, full-annular cascade, where three-dimensional effects could be obtained. Two endwall cooling configurations were tested. In the first configuration, the cooling holes were oriented so that the coolant was injected in line with the inviscid streamline direction. In the second configuration, the coolant was injected at an angle of 15 deg to the inviscid streamline direction and oriented toward the vane pressure surface. In both cases the stator vanes were solid and uncooled so that the effect of endwall cooling could be obtained directly. Total-pressure surveys were taken downstream of the stator vanes over a range of cooling flows at the design, mean-radius, critical velocity ratio of 0.778. Changes in the total-pressure contours downstream of the vanes were used to obtain the effect of endwall cooling on the secondary flows in the stator. Comparisons were made between the two cooled-endwall configurations and with the results obtained previously for solid endwalls.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AGARD Secondary Flows in Turbomachines; 29 p
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  • 17
    Publication Date: 2011-08-18
    Description: Previously cited in issue 07, p. 982, Accession no. A82-19221
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Journal of Guidance, Control, and Dynamics (ISSN 0731-5090); 7; 77-84
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  • 18
    Publication Date: 2011-08-18
    Description: Previously cited in issue 10, p. 1378, Accession no. A83-25963
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Journal of Aircraft (ISSN 0021-8669); 21; 491-497
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  • 19
    Publication Date: 2011-08-18
    Description: Previously cited in issue 10, p. 1377, Accession no. A83-25910
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Journal of Aircraft (ISSN 0021-8669); 21; 453-461
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  • 20
    Publication Date: 2011-08-18
    Description: It is expected that all-electric aircraft, whether military or commercial, will exhibit reduced weight, acquisition cost and fuel consumption, an expanded flight envelope and improved survivability and reliability, simpler maintenance, and reduced support equipment. Also noteworthy are dramatic improvements in mission adaptability, based on the degree to which control system performance relies on easily exchanged software. Flight-critical secondary power and control systems whose malfunction would mean loss of an aircraft pose failure detection and design methodology problems, however, that have only begun to be addressed. NASA-sponsored research activities concerned with these problems and prospective benefits are presently discussed.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: IEEE Transactions on Aerospace and Electronic Systems (ISSN 0018-9251); AES-20; 261-266
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  • 21
    Publication Date: 2011-08-19
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Journal of Guidance, Control, and Dynamics (ISSN 0731-5090); 7; 677-683
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  • 22
    Publication Date: 2011-08-19
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Journal of Guidance, Control, and Dynamics (ISSN 0731-5090); 7; 652-661
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  • 23
    Publication Date: 2011-08-18
    Description: Regulatory changes are proposed for new engine certification for multi-engine helicopters to account for contingency operations when one engine goes out at take-off. The new rules are needed because current regulations define category A and B conditions as one-engine out, land immediately, or continue take-off, respectively. Category A is seldom feasible while Category B requires oversize engines, implying lowered fuel efficiencies. However, NASA studies have shown that engines with large contingency power can operate more efficiently in normal conditions due to decreased coolant flow. Techniques for realizing up to a 50 percent power augmentation with minor modifications of existing engines are described.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Vertiflite (ISSN 0042-4455); 30; 34-38
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  • 24
    Publication Date: 2011-08-18
    Description: A three-dimensional analysis of turbofan forced mixer nozzle aerodynamics demonstrates that the complex flow structure is dominated by geometrically induced secondary flow rather than by turbulence. The test apparatus consisted of a fixed upstream model section and a rotating shroud. The Mach number of the fan and core streams at the mixing plane (lobe exit) was 0.45, the bypass ratio was about 4, and the Reynolds number based on the shroud radius was 1,100,000. The three velocity components near the exit plane of the lobes were measured using flow angularity probes to provide information about the mixer inflow conditions for turbulent computations. The validity of a previous computer code was demonstrated in a comparison of the nozzle exit temperature data with the computed temperature distributions. The mechanism most responsible for the generation of secondary flow within the lobes is due to the turning of the fan and core streams in opposite radial directions.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA Journal (ISSN 0001-1452); 22; 518-525
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  • 25
    Publication Date: 2011-08-18
    Description: Previously cited in issue 12, p. 1742, Accession no. A83-29822
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Journal of Aircraft (ISSN 0021-8669); 21; 278-286
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  • 26
    Publication Date: 2016-06-07
    Description: The impact of gas-turbine-engine-powered aircraft on worldwide pollution was defined within two major areas of contribution. First, the contribution of aircraft to the local air pollution of metropolitan areas and, second, the long-term effects on the chemical balance of the stratosphere of pollutants emitted from future generations of high-altitude, supersonic commercial and military aircraft. Preliminary findings indicate that stratospheric oxides of nitrogen (NOx) emissions may have to be limited to very low levels if, for example, ozone depletion with concomitant increases in sea-level radiation, are to be avoided. Theoretical considerations suggest that (NOx) levels as low as 1.0 gram per kilogram of fuel and less should be attainable from a idealized premixed type of combustor. Experimental rig studies were intended to explore new combustor concepts designed to minimize the formation of (NOx) in aircraft gas turbines and to define their major operational problems and limitations.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Aircraft Eng. Emissions; p 393-415
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  • 27
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    In:  CASI
    Publication Date: 2016-06-07
    Description: The qualitative understanding of soot formation in simple models of gas turbine primary-zone combustors is summarized. Soot formation in flame radiation and air pollution was investigated. Results are presented, namely: (1) if the fuel is premixed with air in approximately stoichiometric proportions, the sequence of states that a fluid element undergoes as it burns is quite different from the sequence when liquid or vapor fuel is injected into an air-flow; (2) swirling flows, as are typical or swirl-can combustors, when burning, can amplify small aerodynamic disturbances upstream of the swirl vanes; and (3) different fuels form significantly different amounts of soot. Each of these effects makes major changes in the amount of soot formed in a given combustor.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Lewis Res. Center Aircraft Eng. Emissions; p 309-321
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  • 28
    Publication Date: 2016-06-07
    Description: The reduction of CO, HC, and smoke emissions while maintaining acceptable NO(x) emissions without affecting fuel consumption, durability, maintainability, and safety was accomplished. Component combustor concept screening directed toward the demonstration of advanced combustor technology required to meet the EPA exhaust emissions standards for class P2 turboprop engines was covered. The combustion system for the Allison 501-D22A engine was used, and three combustor design concepts - reverse flow, prechamber, and staged fuel were evaluated.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Lewis Res. Center Aircraft Eng. Emissions; p 125-147
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  • 29
    Publication Date: 2016-06-07
    Description: Ceramic composite turbine disc protection panels for the A300B were developed using armor technology. Analytical predictions for modifying the ballistic projectile armor system were verified by a test program conducted to qualify the rotor containment system. With only a slight change in the areal density of the armor system a more than two-fold increase in kinetic energy protection level was achieved. Thickness of the fiberglass reinforced plastic backing material was increased to achieve an optimum ratio of ceramic thickness to backing thickness for the different ballistic defeat condition.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: MIT An Assessment of Technol. for Turbojet Engine Rotor Failures; p 277-293
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  • 30
    Publication Date: 2016-06-07
    Description: Improvements in both quality and durability of disk raw material for both military and commercial engines necessitated an entirely new concept in raw material process control which imposes careful selection, screening and sampling of the basic alloy ingredients, followed by careful monitoring of the melting parameters in all phases of the vacuum melting sequence. Special care is taken to preclude solidification conditions that produce adverse levels of segregation. Melt furnaces are routinely cleaned and inspected for contamination. Ingots are also cleaned and inspected before entering the final melt step.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: MIT An Assessment of Technol. for Turbojet Engine Rotor Failures; p 347-368
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  • 31
    Publication Date: 2016-06-07
    Description: Computer codes were developed for simulating the dynamic fracture and viscoelastic constitutive response due to stress wave interaction and reflections caused by ballistic impact on woven textiles. The method, which was developed for use in the design and analysis of protection devices for personnel armor, has potential for use in studies of rotor blade burst containment at high velocity. Alterations in coding required for burst containment problems are discussed.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Assessment of Technol. for Turbojet Engine Rotor Failures; p 247-260
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  • 32
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    In:  CASI
    Publication Date: 2016-06-07
    Description: Kevlar fabric styles and weaves were studied, as well as methods of application for advanced gas turbine engines. The Kevlar material was subjected to high speed impacts by simple projectiles fired from a rifle, as well as more complex shapes such as fan blades released from gas turbine rotors in a spin pit. Just contained data was developed for a variety of weave and/or application techniques, and a comparative containment weight efficiency was established for Kevlar containment applications. The data generated during these tests is being incorporated into an analytical design system so that blade containment trade-off studies between Kevlar and metal case engine structures can be made. Laboratory tests and engine environment tests were performed to determine the survivability of Kevlar in a gas turbine environment.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: MIT An Assessment of Technol. for Turbojet Engine Rotor Failures; p 235-245
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  • 33
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    In:  CASI
    Publication Date: 2016-06-07
    Description: Key airworthiness design criteria considerations for fragment protection as found in various FAA requirements in FAR Parts 25 and 33, and in interpretive 8110 orders are reviewed. The impact of providing aircraft armor in lieu of engine armor for typical three- and four-engine wide bodied transports for protection within the length of the engine case as well as from fragments exiting ahead of the enlet engine inlet flange is assessed. For protection within the length of the engine case, armor weight penalties, plus fuel burned and dollar cost of carrying the armor protection are defined. Immediately ahead of the inlet flange, direct tangential impacts are predominant, but further forward, rebound impacts predominate. Armor thickness requirements and fuel cost impact of protection are given.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: MIT An Assessment of Technol. for Turbojet Engine Rotor Failures; p 101-103
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  • 34
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    In:  CASI
    Publication Date: 2016-06-07
    Description: Airworthiness accidents account for roughly one quarter of the total number of accidents to public transport turbojet aircraft. The most reliable, practicable, and cost-effective means of minimizing damage outside the confines of the nacelle is to make the aircraft design invulnerable to any debris which may affect the aircraft. A failure model was developed for use by aircraft builders in measuring the freedom from catastrophe factor of their design.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: MIT An Assessment of Technol. for Turbojet Engine Rotor Failures; p 11-32
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  • 35
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    In:  CASI
    Publication Date: 2016-06-07
    Description: Modern jet engine design imposes extremely high loadings and temperatures on hot section components. A series of interdisciplinary modeling and analysis techniques which were specialized to address three specific components (combustor burner linings, hollow air-cooled turbine blades, and air-cooled turbine vanes) were developed and verified. These techniques will incorporate data as well as theoretical methods from many diverse areas, including cycle and performance analysis, heat transfer analysis, linear and nonlinear stress analysis, and mission analysis. Building on the proven techniques already available in these fields, the new methods developed will be integrated to predict temperature, deformation, stress, and strain histories throughout a complete flight mission.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Lewis Research Center Turbine Engine Hot Section Technology, 1984; 12 p
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  • 36
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    In:  CASI
    Publication Date: 2016-06-07
    Description: A serious problem exists interfacing the output temperatures and temperature gradients from either the heat transfer codes or engine tests with the input to stress analysis codes. A thermal load transfer code was developed and was used in conjunction with a three-dimensional model of a combustor liner for verification. The 3D heat transfer and stress analysis models of combustor liners and turbine blades were used to validate the mapped temperature produced by the transfer module. Verification cases were made for both finite element and finite difference heat transfer codes. A user manual for the code was written and is available.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Lewis Research Center Turbine Engine Hot Section Technology, 1984; 9 p
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  • 37
    Publication Date: 2016-06-07
    Description: A typical engine control design cycle consists of developing a dynamic engine simulation from steady-state component performance data, designing a control based upon this simulation, and then testing and modifying the control in an engine test cell to meet performance requirements. This design cycle was successful for state-of-the-art engines. However, for more advanced multivariable engines that exhibit strong variable interactions, this procedure will result in substantial trial and error modification of the control during the testing phase. One method to automate the design process and reduce control modification testing and development cost would be to identify accurate dynamic models directly from the closed-loop test data. These identified models would then be used in conjunction with a synthesis procedure to systematically refine the control. Recent advances in closed-loop identifiability present a methodology for this direct identification of engine model dynamics from closed-loop test data. The application of an identification method to simulated and actual closed-loop F100 engine data is described. This study was undertaken to determine if useful dynamic engine models could be identified directly from closed-loop engine test data.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Langley Research Center NASA Aircraft Controls Research, 1983; p 221-238
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  • 38
    Publication Date: 2016-06-07
    Description: The effects of inlet pressure, temperature, and humidity on the oxides of nitrogen produced by an engine operating at takeoff power setting were investigated and numerous correction factors were formulated. The effect of ambient relative humidity on gas turbine idle emissions was ascertained. Experimentally, a nonvitiating combustor rig was employed to simulate changing combustor inlet conditions as generated by changing ambient conditions. Emissions measurements were made at the combustor exit. For carbon monoxide, a reaction kinetic scheme was applied within each zone of the combustor where initial species concentrations reflected not only local combustor characteristics but also changing ambient conditions.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Lewis Res. Center Aircraft Eng. Emissions; p 437-456
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  • 39
    Publication Date: 2016-06-07
    Description: Automated instruments were installed on a commercial B-747 aircraft, during the program, to obtain baseline data and to monitor key atmospheric constituents associated with emissions of aircraft engines in order to determine if aircraft are contributing to pollution of the upper atmosphere. Data thus acquired on a global basis over the commercial air routes for 5 to 10 years will be analyzed. Ozone measurements in the 29,000 to 45,000 foot altitude were expanded over what has been available from ozonesondes. Limited aerosol composition measurements from filter samples show low levels of sulfates and nitrates in the upper troposphere. Recently installed instruments for measurement of carbon monoxide and condensation nuclei are beginning to return data.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Aircraft Eng. Emissions; p 323-355
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  • 40
    Publication Date: 2016-06-07
    Description: The similarities and differences of emissions reduction technology for aircraft and ground power gas turbines is described. The capability of this technology to reduce ground power emissions to meet existing and proposed emissions standards is presented and discussed. Those areas where the developing aircraft gas turbine technology may have direct application to ground power and those areas where the needed technology may be unique to the ground power mission are pointed out. Emissions reduction technology varying from simple combustor modifications to the use of advanced combustor concepts, such as catalysis, is described and discussed.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Aircraft Eng. Emissions; p 203-242
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  • 41
    Publication Date: 2016-06-07
    Description: Small jet aircraft engines (EPA class T1, turbojet and turbofan engines of less than 35.6 kN thrust) were evaluated with the objective of attaining emissions reduction consistent with performance constraints. Configurations employing the technological advances were screened and developed through full scale rig testing. The most promising approaches in full-scale engine testing were evaluated.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Lewis Res. Center Aircraft Eng. Emissions; p 149-180
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  • 42
    facet.materialart.
    Unknown
    In:  CASI
    Publication Date: 2016-06-07
    Description: Combustor concepts having the potential for significantly lower emissions levels were investigated. The combustor emissions reduction was measured in an engine test. Emission characteristics common to all engine classes are shown. Multiple-burning zone combustors, specifically the double-annular and swirl-can combustors were studied. Airblast and air-assist fuel injection techniques were evaluated for emissions control potential. The combustor sceening and refining phases are summarized.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Aircraft Eng. Emissions; p 19-58
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  • 43
    facet.materialart.
    Unknown
    In:  CASI
    Publication Date: 2016-06-07
    Description: Advanced disk structural concepts were employed to improve the cyclic lives and reliability of turbine disks. Analytical studies were conducted to evaluate bore-entry disks as potential replacements for the existing first-stage turbine disks in the CF6-50 and JT8D-17 engines. Results of low cycle fatigue, burst, fracture mechanics, and fragment energy analyses are summarized for the advanced disk designs and the existing disk designs, with both conventional and advanced disk materials. Other disk concepts such as composite, laminated, link, multibore, multidisk, and spline disks were also evaluated for the CF6-50 engine.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: MIT An Assessment of Technol. for Turbojet Engine Rotor Failures; p 389-411
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  • 44
    Publication Date: 2016-06-07
    Description: Several empirical and analytical approaches to rotor burst shield sizing are compared and principal differences in metal and fabric dynamic behavior are discussed. The application of transient structural response computer programs to predict Kevlar containment limits is described. For preliminary shield sizing, present analytical methods are useful if insufficient test data for empirical modeling are available. To provide other information useful for engineering design, analytical methods require further developments in material characterization, failure criteria, loads definition, and post-impact fragment trajectory prediction.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: MIT An Assessment of Technol. for Turbojet Engine Rotor Failures; p 261-275
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  • 45
    facet.materialart.
    Unknown
    In:  CASI
    Publication Date: 2016-06-07
    Description: Current aircraft design practices to minimize the hazard from rotor bursts are described. The consequences of non-contained engine failures and the impact of rotor burst protection systems on aircraft design are discussed.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: MIT An Assessment of Technol. for Turbojet Engine Rotor Failures; p 37-43
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  • 46
    Publication Date: 2017-10-02
    Description: The problem of calculating turbine engine component durability is addressed. Nonlinear, finite-element structural analyses, cyclic constitutive behavior models, and an advanced creep-fatigue life prediction method called strainrange partitioning were assessed for their applicability to the solution of durability problems in hot-section components of gas turbine engines. Three different component or subcomponent geometries are examined: a stress concentration in a turbine disk; a louver lip of a half-scale combustor linear; and a squealer tip of a first-stage high-pressure turbine blade. Cyclic structural analyses were performed for all three problems. The computed strain-temperature histories at the critical locations of the combustor linear and turbine blade components were imposed on smooth specimens in uniaxial, strain-controlled, thermomechanical fatigue tests of evaluate the structural and life analysis methods.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AGARD Eng. Cyclic Durability by Analysis and Testing; 12 p
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  • 47
    Publication Date: 2016-06-07
    Description: The fundamental processes controlling lean combustion were observed for better understanding, with particular emphasis on the formation and measurement of gas-phase pollutants, the stability of the combustion process (blowout limits), methods of improving stability, and the application of probe and optical diagnostics for flow field characterization, temperature mapping, and composition measurements. The following areas of investigation are described in detail: (1) axisymmetric, opposed-reacting-jet-stabilized combustor studies; (2) stabilization through heat recirculation; (3) two dimensional combustor studies; and (4) spectroscopic methods. A departure from conventional combustor design to a premixed/prevaporized, lean combustion configuration is attractive for the control of oxides of nitrogen and smoke emissions, the promotion of uniform turbine inlet temperatures, and, possibly, the reduction of carbon monoxide and hydrocarbons at idle.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Lewis Res. Center Aircraft Eng. Emissions; p 417-436
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  • 48
    Publication Date: 2016-06-07
    Description: Potential problems related to the use of alternative aviation turbine fuels are discussed and both ongoing and required research into these fuels is described. This discussion is limited to aviation turbine fuels composed of liquid hydrocarbons. The advantages and disadvantages of the various solutions to the problems are summarized. The first solution is to continue to develop the necessary technology at the refinery to produce specification jet fuels regardless of the crude source. The second solution is to minimize energy consumption at the refinery and keep fuel costs down by relaxing specifications.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Aircraft Eng. Emissions; p 277-308
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  • 49
    Publication Date: 2016-06-07
    Description: The NASA emissions reduction contract programs for EPA aircraft engine classes P2 (turboshaft engines), T1 (jet engines with thrust under 8000 lb), T4 (JT8D) engines), and T2 (jet engines with thrust over 8000 lb) are discussed. The most important aspects of these programs, the commonality of approaches used, the test results, and assessments regarding applications of the derived technology are summarized.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Aircraft Eng. Emissions; p 181-202
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  • 50
    Publication Date: 2016-06-07
    Description: A two-stage vorbix (vortex burning and mixing) combustor and associated fuel system components were successfully tested in an experimental JT9D engine at steady-state and transient operating conditions, using ASTM Jet-A fuel. Full-scale JT9D experimental engine tests were conducted in a phase three aircraft experimental clean combustor program. The low-pollution combustor, fuel system, and fuel control concepts were derived from phase one and phase two programs in which several combustor concepts were evaluated, refined, and optimized in a component test rig. Significant pollution reductions were achieved with the combustor which meets the performance, operating, and installation requirements of the engine.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Lewis Res. Center Aircraft Eng. Emissions; p 91-123
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  • 51
    Publication Date: 2016-06-07
    Description: A recently implemented NASA effort specifically aimed at reducing cruise oxides of nitrogen from high-altitude aircraft is discussed. The desired emission levels and the combustor technology required to achieve them are discussed. A brief overview of the SCERP operating plan is given. Lean premixed-prevaporized combustion and some of the potential difficulties that are associated with applying this technique to gas turbine combustors are examined. Base technology was developed in several key areas. These fundamental studies are viewed as a requirement for successful implementation of the lean premixed combustion technique.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Aircraft Eng. Emissions; p 357-391
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  • 52
    Publication Date: 2016-06-07
    Description: To support the promulgation of aircraft regulations, two airports were examined, Van Nuys and Tamiami. It was determined that the carbon monoxide (CO) emissions from piston-engine aircraft have a significant influence on the CO levels in the ambient air in and around airports, where workers and travelers would be exposed. Emissions standards were set up for control of emissions from aircraft piston engines manufactured after December 31, 1979. The standards selected were based on a technologically feasible and economically reasonable control of carbon monoxide. It was concluded that substantial CO reductions could be realized if the range of typical fuel-air ratios could be narrowed. Thus, improvements in fuel management were determined as reasonable controls.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Aircraft Eng. Emissions; p 243-275
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  • 53
    Publication Date: 2016-06-07
    Description: The technology required to develop commercial gas turbine engines with reduced exhaust emissions was demonstrated. Can-annular combustor systems for the JT8D engine family (EPA class T4) were investigated. The JT8D turbofan engine is an axial-flow, dual-spool, moderate-bypass-ratio design. It has a two-stage fan, a four-stage low-pressure compressor driven by a three-stage low-pressure turbine, and a seven-stage high-pressure compressor driven by a single-stage high-pressure turbine. A cross section of the JT8D-17 showing the mechanical configuration is given. Key specifications for this engine are listed.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Aircraft Eng. Emissions; p 29-89
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  • 54
    facet.materialart.
    Unknown
    In:  CASI
    Publication Date: 2016-06-07
    Description: Two classes of fan blade fragments were considered in an analysis of blade fragment energy. The first, of relatively small size (.15 pound) and energy, tends to rebound from the fan and case when liberated in an FOD encounter. These small fragments have relatively low secondary damage potential and are less demanding in terms of protection. The larger fan blade fragments are ejected in a more direct release trajectory with higher energy and hence can represent a higher potential hazard. Simplified analytical methods were used to describe blade fragment energy transfer kinematics, establish fragment energy levels, evaluate damage potential and configure protection. The approach, methodology, and application are discussed as a possible building block for other applications. Development of effective local protection using Kevlar is also discussed. Analysis methods developed and applied to the rebound fragment problem and to the large direct release fragment problem are described.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: MIT An Assessment of Technol. for Turbojet Engine Rotor Failures; p 93-95
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  • 55
    Publication Date: 2016-06-07
    Description: Tests were conducted in translational launchers and spin pits to generate empirical data used in the design of a Kevlar shield for containing engine burst debris. Methods are given for modeling the relationship of fragment characteristics to shielding requirements. The change in relative importance of shield mounting provisions as fragment energy is increased is discussed.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: MIT An Assessment of Technol. for Turbojet Engine Rotor Failures; p 217-234
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  • 56
    Publication Date: 2016-06-07
    Description: Noncontained rotor failures in U.K. engines resulting from low cycle fatigue, low cycle fatigue with superimposed high cycle fatigue, and overheating and-or overspeeding were analyzed. The size, shape, weight, velocity, energy, and direction of the fragments released from turbines and compressors were studied and are presented in graph.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: MIT An Assessment of Technol. for Turbojet Engine Rotor Failures; p 65-92
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  • 57
    Publication Date: 2016-06-07
    Description: Design philosophies used in the L-1011 aircraft to provide protection against rotor fragments include: (1) incorporating into the rotor design features that tend to promote small fragments if failure occurs; (2) containing the fragments within the engine shell or greatly reducing the energy content of those fragments that are eventually uncontained; (3) shielding vulnerable elements or systems with heavy structural members that tend to stop or deflect high velocity fragments; and (4) incorporating redundant and/or backup systems into the basic design and separating these systems so as to minimize the probability that more than one system will be damaged by an uncontained rotor fragment. Some of the design features that were incorporated into the Rolls-Royce RB211 engine are discussed, and two in-service experiences are considered in order to illustrate the practical operation of these features.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: MIT An Assessment of Technol. for Turbojet Engine Rotor Failures; p 97-100
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  • 58
    Publication Date: 2018-12-01
    Description: Requirements for increased durability of gas turbine hot section structural components have made it necessary to place greater emphasis on accurate structural analysis and life prediction. Linear finite-element analysis is generally sufficient for structural analysis applications. However, for structures in the hot part of the engine, nonlinear structural analysis may be required under certain conditions for the accurate prediction of the local stress-strain response. Nonlinear finite element analysis represents a costly effort which is generally incompatible with the iterative nature of the design process. The present investigation is, therefore, concerned with two simplified procedures for estimating the local hysteretic response produced by cyclic thermal loading. These procedures reduce the need for nonlinear finite-element analysis.
    Keywords: AIRCRAFT PROPULSION AND POWER
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  • 59
    Publication Date: 2019-06-28
    Description: The need for a more sophisticated engine control system is discussed. The improvements in better thrust-to-weight ratios demand the manipulation of more control inputs. New technological solutions to the engine control problem are practiced. The digital electronic engine control (DEEC) system is a step in the evolution to digital electronic engine control. Technology issues are addressed to ensure a growth in confidence in sophisticated electronic controls for aircraft turbine engines. The need of a control system architecture which permits propulsion controls to be functionally integrated with other aircraft systems is established. Areas of technology studied include: (1) control design methodology; (2) improved modeling and simulation methods; and (3) implementation technologies. Objectives, results and future thrusts are summarized.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: PAPER-14 , Digital Electronic Engine Control (DEEC) Flight Evaluation in an F-15 Airplane; p 231-247
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  • 60
    Publication Date: 2019-06-28
    Description: The digital electronic engine control (DEEC) system installed on an F100 engine in an F-15 aircraft was tested. The DEEC system incorporates a closed-loop air start feature in which the fuel flow is modulated to achieve the desired rate of compressor acceleration. With this logic the DEEC equipped F100 engine can achieve air starts over a larger envelope. The DEEC air start logic, the test program conducted on the F-15, and its results are described.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: PAPER-8 , Digital Electronic Engine Control (DEEC) Flight Evaluation in an F-15 Airplane; p 127-139
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  • 61
    Publication Date: 2019-06-28
    Description: This paper describes the development of the analysis of the transient dynamic response of a bladed disk on a flexible rotor. The rotating flexible bladed disk is considered as a module in a complete turbine engine structure. The analysis of the flexible bladed disk (FBD) module is developed for the non-equilibrated one-diameter axial mode. The FBD motion is considered as a sum of two standing axial waves constrained to the rotor. The FBD is coupled inertially and gyroscopically to its rotor support, and indirectly through connecting elements, to the adjacent rotor and/or other supporting structures. Incorporated in the basic Turbine Engine Transient Response Analysis program (TETRA), the FBD module is demonstrated with a two-rotor model where the FBD can be excited into resonance by an unbalance in the adjacent rotor and at a frequency equal to the differential rotor speed. The FBD module also allows the analysis of two flexible bladed disks in the same rotor.
    Keywords: AIRCRAFT PROPULSION AND POWER
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  • 62
    facet.materialart.
    Unknown
    In:  Other Sources
    Publication Date: 2019-06-28
    Description: The task of the aeroelastic analysis is to combine the formulations of the structural dynamic and unsteady aerodynamic models in a consistent manner, to solve the resulting aeroelastic model to determine the dynamic behavior (e.g., stability, forced vibration), and to interpret those results for both qualitative trends, and quantitative detail. A review of the various formulations of the aeroelastic problem and a comparison of their relative advantages will be the subject of this paper. Specifically, the topics to be addressed are: the formulation of the aeroelastic problem, including a summary of the relations necessary to transform various diverse structural and aerodynamic models to a consistent notation for oscillatory motion; an approximate transformation for arbitrary temporal behavior; and a brief review of the applicable solution techniques.
    Keywords: AIRCRAFT PROPULSION AND POWER
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  • 63
    Publication Date: 2019-06-28
    Description: Computer algorithms which calculate in-flight engine and aircraft performance real-time are discussed. The first step was completed with the implementation of a real-time thrust calculation program on a digital electronic engine control (DEEC) equiped F100 engine in an F-15 aircraft. The in-flight thrust modifications that allow calculations to be performed in real-time, to compare results to predictions, are presented.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: PAPER-13 , Digital Electronic Engine Control (DEEC) Flight Evaluation in an F-15 Airplane; p 231-247
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  • 64
    Publication Date: 2019-06-28
    Description: An F100 augmented turbofan engine equipped with digital electronic engine control (DEEC) system was evaluated. The engine was equipped with a specially modified augmentor to provide improved steady state and transient augmentor capability. The combination of the DEEC and the modified augmentor was evaluated in sea level and altitude facility tests and then in four different flight phases in an F-15 aircraft. The augmentor configuration, logic, and test results are presented.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: PAPER-11 , Digital Electronic Engine Control (DEEC) Flight Evaluation in an F-15 Airplane; p 171-199
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  • 65
    Publication Date: 2019-06-28
    Description: The capabilities and performance of various fault detection and accommodation (FDA) schemes in existing and projected engine control systems were investigated. Flight tests of the digital electronic engine control (DEEC) in an F-15 aircraft show discrepancies between flight results and predictions based on simulation and altitude testing. The FDA methodology and logic in the DEEC system, and the results of the flight failures which occurred to date are described.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: PAPER-7 , Digital Electronic Engine Control (DEEC) Flight Evaluation in n F-15 Airplane; p 107-126
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  • 66
    Publication Date: 2019-06-28
    Description: The digital electronic engine control (DEEC) is a full-authority digital engine control developed for the F100-PW-100 turbofan engine which was flight tested on an F-15 aircraft. The DEEC hardware and software throughout the F-15 flight envelope was evaluated. Real-time data reduction and data display systems were implemented. New test techniques and stronger coordination between the propulsion test engineer and pilot were developed which produced efficient use of test time, reduced pilot work load, and greatly improved quality data. The engine pressure ratio (EPR) control mode is demonstrated. It is found that the nonaugmented throttle transients and engine performance are satisfactory.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: PAPER-6 , Digital Electronic Engine Control (DEEC) Flight Evaluation in an F-15 Airplane; p 91-105
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  • 67
    Publication Date: 2019-06-28
    Description: An instability in the nozzle of the F100 engine, equipped with a digital electronic engine control (DEEC), was observed during a flight evaluation on an F-15 aircraft. The instability occurred in the upper left hand corner (ULMC) of the flight envelope during augmentation. The instability was not predicted by stability analysis, closed-loop simulations of the the engine, or altitude testing of the engine. The instability caused stalls and augmentor blowouts. The nozzle instability and the altitude testing are described. Linear analysis and nonlinear digital simulation test results are presented. Software modifications on further flight test are discussed.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: PAPER-12 , Digital Electronic Engine Control (DEEC) Flight Evaluation in an F-15 Airplane; p 201-214
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  • 68
    Publication Date: 2019-06-28
    Description: Problems encountered in obtaining good engine face pressure data were studied. A single static measurement located upstream of the engine hub in the stream flow was found to provide a pressure signal suitable for engine control. Two identical probes for measuring fan inlet static (PS2) pressure were designed and mounted on the hub of the left F100-PW-100 turbofan engine installed in the F-15 test aircraft for flight evaluation. The probe is used as a static pressure sensor for a digital engine control system.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: PAPER-5 , Digital Electronic Engine Control Flight Evaluation in an F-15 Airplane; p 73-89
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  • 69
    Publication Date: 2019-06-28
    Description: A digital electronic engine control (DEEC) was developed for use on the F100-PW-100 turbofan engine. This control system has full authority control, capable of moving all the controlled variables over their full ranges. The digital computational electronics and fault detection and accomodation logic maintains safe engine operation. A hydromechanical backup control (BUC) is an integral part of the fuel metering unit and provides gas generator control at a reduced performance level in the event of an electronics failure. The DEEC's features, hardware, and major logic diagrams are described.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: PAPER-3 , Digital Electronic Engine Control (DEEC) Flight Evaluation in an F-15 Airplane; p 33-53
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  • 70
    facet.materialart.
    Unknown
    In:  CASI
    Publication Date: 2019-06-28
    Description: Full authority digital electronic engine controls (DEECs) were studied, developed, and ground tested because of projected benefits in operability, improved performance, reduced maintenance, improved reliability, and lower life cycle costs. The issues of operability and improved performance, however, are assessed in a flight test program. The DEEC on a F100 engine in an F-15 aircraft was demonstrated and evaluated. The events leading to the flight test program are chronicled and important management and technical results are identified.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: PAPER-2 , Digital Electronic Engine Control (DEEC) Flight Evaluation in an F-15 Airplane; p 15-31
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  • 71
    Publication Date: 2019-06-28
    Description: The assembly of SR5 advanced turboprop blades to develop a structural dynamic data base for swept props is reported. Steady state blade deformation under centrifugal loading and vibratory characteristics of the rotor assembly were measured. Vibration was induced through a system of piezoelectric crystals attached to the blades. Data reduction procedures are used to provide deformation, mode shape, and frequencies of the assembly at predetermined speeds.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-174708 , NAS 1.26:174708 , R84-956627-1
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  • 72
    Publication Date: 2019-06-28
    Description: 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.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-174652 , NAS 1.26:174652 , G-21-4314-2
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  • 73
    Publication Date: 2019-06-28
    Description: Two major problems identified with the design of the blade-root/hub interface are discussed. The first is the so-called friction contact problem which has two special features: unilateral contact and Coulomb's friction. One of the difficulties in this problem is that the portions of contact and sticking/sliding surfaces are not known a priori. The second is the shape optimization problem which is characterized either by the minimization of the maximum contact pressure or by the minimization of the equivalent stress on the boundary. Design variables are the shapes of the blade-root and the hub. It is noted that friction contact and shape optimization problems are strongly coupled in the present design problem.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Langley Research Center Recent Experiences in Multidisciplinary Analysis and Optimization, Part 2; 14 p
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  • 74
    Publication Date: 2019-06-28
    Description: In the development of modern turbomachinery, problems of flutter instabilities and excessive forced response of a cascade of blades that were encountered have often turned out to be extremely difficult to eliminate. The study of these instabilities and the forced response is complicated by the presence of mistuning; that is, small differences among the individual blades. The theory of mistuned cascade behavior shows that mistuning can have a beneficial effect on the stability of the rotor. This beneficial effect is produced by the coupling between the more stable and less stable flutter modes introduced by mistuning. The effect of mistuning on the forced response can be either beneficial or adverse. Kaza and Kielb have studied the effects of two types of mistuning on the flutter and forced response: alternate mistuning where alternte blades are identical and random mistuning. The objective is to investigate other patterns of mistuning which maximize the beneficial effects on the flutter and forced response of the cascade. Numerical optimization techniques are employed to obtain optimal mistuning patterns. The optimization program seeks to minimize the amount of mistuning required to satisfy constraints on flutter speed and forced response.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Langley Research Center Recent Experiences in Multidisciplinary Analysis and Optimization, Part 1; 15 p
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  • 75
    Publication Date: 2019-06-28
    Description: Plasma-sprayed thermal barrier coatings (TBCs) will enable turbine components to operate at higher temperatures and lower cooling gas flow rates; thereby improving their efficiency. Future developments are limited by precise knowledge of the material properties and failure mechanisms of the coating system. Details of this nature are needed for realistic modeling of the coating system which will, in turn, promote advancements in coating technology. Complementary experiments and analytical modeling which were undertaken in order to define and measure the important failure processes for plasma-sprayed coatings are presented. The experimental portion includes two different tests which were developed to measure coating properties. These are termed tensile adhesion and acoustic emission tests. The analytical modeling section details a finite element method which was used to calculate the stress distribution in the coating system. Some preliminary results are presented.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Lewis Research Center Turbine Engine Hot Section Technology, 1984; 12 p
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  • 76
    facet.materialart.
    Unknown
    In:  CASI
    Publication Date: 2019-06-28
    Description: Gas turbine failures associated with sea-salt ingestion and sulfur-containing fuel impurities have directed attention to alkali sulfate deposition and the associated hot corrosion of gas turbine (GT) blades under some GT operating conditions. These salt deposits form thin, molten films which undermine the protective metal oxide coating normally found on GT blades. The prediction of molten salt deposition, flow and oxide dissolution, and their effects on the lifetime of turbine blades are examined. Goals include rationalizing and helping to predict corrosion patterns on operational GT rotor blades and stators, and ultimately providing some of the tools required to design laboratory simulators and future corrosion-resistant high-performance engines. Necessary background developments are reviewed first, and then recent results and tentative conclusions are presented along with a brief account of the present research plans.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Lewis Research Center Turbine Engine Hot Section Technology, 1984; 22 p
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  • 77
    Publication Date: 2019-06-28
    Description: An experimental investigation was conducted into the response of a small-turboshaft-engine compression system to steady-state and transient inlet temperature distortions. Transient temperature ramps range from less than 100 K/sec to above 610 K/sec and generated instantaneous temperatures to 420 K above ambient. Steady-state temperature distortion levels were limited by the engine hardware temperature list. Simple analysis of the steady-state distortion data indicated that a particle separator at the engine inlet permitted higher levels of temperature distortion before onset of compressor surge than would be expected without the separator.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-83765 , E-2198 , NAS 1.26:83765 , USAAVSCOM-TR-84-C-13
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  • 78
    Publication Date: 2019-06-28
    Description: Local heat transfer distributions in impingement cooling have been measured by Kreatsoulas and Prieser for a range of conditions which model those in actual turbine blades, including the effects of rotation. These data were reported as local Nusselt numbers, but referred to coolant supply conditions. By means of a channel flow modeling of the flow in the supply and impingement passages, the same data are here presented in terms of local Nusselt number distributions such as are used in design. The results in this form are compared to the nonrotating impingement results of Chupp and to the rotating but nonimpingement results of Morris. Rotation reduces the mean Nusselt numbers from these found by Chupp by about 30 percent, and introduces important radial variations which are sensitive to rotation and to leading edge stagger angle.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-177206 , NAS 1.26:177206 , GTPDL-181
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  • 79
    facet.materialart.
    Unknown
    In:  CASI
    Publication Date: 2019-06-28
    Description: A flight test evaluation of the digital elctronic engine control (DEEC) system was conducted. An overview of the flight program is presented. The roles of the participating parties, the system, and the flight program objectives are described. The test program approach is discussed, and the engine performance benefits are summarized. A description of the follow-on programs is included.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: PAPER-1 , Digital Electronic Engine Control (DEEC) Flight Evaluation in an F-15 Airplane; p 1-14
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  • 80
    Publication Date: 2019-06-28
    Description: The air start capability of a backup control (BUC) was tested for a digital electronic engine control (DEEC) equipped F100 engine, which was installed in an F-15 aircraft. Two air start schedules were tested. Using the group 1 start schedule, based on a 40 sec timer, an air speed of 300 knots was required to ensure successful 40 and 25% BUC mode spooldown airstarts. If core rotor speed (N2) was less than 40% a stall would occur when the start bleed closed, 40 sec after initiation of the air start. All jet fuel starter (JFS) assisted air starts were successful with the group 1 start schedule. For the group 2 schedule, the time between pressurization and start bleed closure ranged between 50 sec and 72 sec. Idle rps was lower than the desired 65% for air starts at higher altitudes and lower air speeds.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: PAPER-10 , Digital Electronic Engine Control (DEEC) Flight Evaluation in an F-15 Airplane; p 157-170
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  • 81
    Publication Date: 2019-06-28
    Description: The backup control (BUC) features, the operation of the BUC system, the BUC control logic, and the BUC flight test results are described. The flight test results include: (1) transfers to the BUC at military and maximum power settings; (2) a military power acceleration showing comparisons bvetween flight and simulation for BUC and primary modes; (3) steady-state idle power showing idle compressor speeds at different flight conditions; and (4) idle-to-military power BUC transients showing where cpmpressor stalls occurred for different ramp rates and idle speeds. All the BUC transfers which occur during the DEEC flight program are initiated by the pilot. Automatic transfers to the BUC do not occur.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: PAPER-9 , Digital Electronic Engine Control (DEEC) Flight Evaluation in an F-15 Airplane; p 141-155
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  • 82
    Publication Date: 2019-06-28
    Description: Two builds of an F100 engine model derivative (EMD) engine were evaluated for improvements in engine components and digital electronic engine control (DEEC) logic. Two DEEC flight logics were verified throughout the flight envelope in support of flight clearance for the F100 engine model derivative program (EMPD). A nozzle instability and a faster augmentor transient capability was investigated in support of the F-15 DEEC flight program. Off schedule coupled system mode fan flutter, DEEC nose-boom pressure correlation, DEEC station six pressure comparison, and a new fan inlet variable vane (CIVV) schedule are identified.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: PAPER-4 , Digital Electronic Engine Control (DEEC) Flight Evaluation in an F-15 Airplane; p 55-71
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  • 83
    Publication Date: 2019-06-28
    Description: The Energy Efficient Engine (E3) combustor effort was conducted as part of the overall NASA/GE E3 Program. This effort included the selection of an advanced double-annular combustion system design. The primary intent of this effort was to evolve a design that meets the stringent emissions and life goals of the E3, as well as all of the usual performance requirements of combustion systems for modern turbofan engines. Numerous detailed design studies were conducted to define the features of the combustion system design. Development test hardware was fabricated, and an extensive testing effort was undertaken to evaluate the combustion system subcomponents in order to verify and refine the design. Technology derived from this effort was incorporated into the engine combustion hardware design. The advanced engine combustion system was then evaluated in component testing to verify the design intent. What evolved from this effort was an advanced combustion system capable of satisfying all of the combustion system design objectives and requirements of the E3.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-168274 , NAS 1.26:168274 , R82AEB401
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  • 84
    Publication Date: 2019-06-28
    Description: The Energy Efficient Engine (E3) Combustor Development effort was conducted as part of the overall NASA/GE E3 Program. This effort included the selection of an advanced double-annular combustion system design. The primary intent was to evolve a design which meets the stringent emissions and life goals of the E3 as well as all of the usual performance requirements of combustion systems for modern turbofan engines. Numerous detailed design studies were conducted to define the features of the combustion system design. Development test hardware was fabricated, and an extensive testing effort was undertaken to evaluate the combustion system subcomponents in order to verify and refine the design. Technology derived from this development effort will be incorporated into the engine combustion system hardware design. This advanced engine combustion system will then be evaluated in component testing to verify the design intent. What is evolving from this development effort is an advanced combustion system capable of satisfying all of the combustion system design objectives and requirements of the E3. Fuel nozzle, diffuser, starting, and emissions design studies are discussed.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-168301 , NAS 1.26:168301 , R82AEB472
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  • 85
    Publication Date: 2019-06-28
    Description: The high pressure turbine for the General Electric Energy Efficient Engine is a two stage design of moderate loading. Results of detailed system studies led to selection of this configuration as the most appropriate in meeting the efficiency goals of the component development program. To verify the design features of the high pressure turbine, a full scale warm air turbine test rig with cooling flows simulated was run. Prior to this testing, an annular cascade test was run to select vane unguided turn for the first stage nozzle. Results of this test showed that the base configuration exceeded the lower unguided turning configuration by 0.48 percent in vane kinetic energy efficiency. The air turbine test program, consisting of extensive mapping and cooling flow variation as well as design point evaluation, demonstrated a design point efficiency level of 90.0 percent based on the thermodynamic definition. In terms of General Electric cycle definition, this efficiency was 92.5 percent. Based on this test, it is concluded that efficiency goals for the Flight Propulsion System were met.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-168289 , NAS 1.26:168289 , R82AEB406
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  • 86
    Publication Date: 2019-06-28
    Description: The Phase 3 exhaust mixer test program was conducted to explore the trends established during previous Phases 1 and 2. Combinations of mixer design parameters were tested. Phase 3 testing showed that the best performance achievable within tailpipe length and diameter constraints is 2.55 percent better than an optimized separate flow base line. A reduced penetration design achieved about the same overall performance level at a substantially lower level of excess pressure loss but with a small reduction in mixing. To improve reliability of the data, the hot and cold flow thrust coefficient analysis used in Phases 1 and 2 was augmented by calculating percent mixing from traverse data. Relative change in percent mixing between configurations was determined from thrust and flow coefficient increments. The calculation procedure developed was found to be a useful tool in assessing mixer performance. Detailed flow field data were obtained to facilitate calibration of computer codes.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-174799 , NAS 1.26:174799 , PWA-5594-271-ADD
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  • 87
    Publication Date: 2019-06-28
    Description: The results of the first year of work on a program to validate unified constitutive models for isotropic materials utilized in high temperature regions of gas turbine engines and to demonstrate their usefulness in computing stress-strain-time-temperature histories in complex three-dimensional structural components. The unified theories combine all inelastic strain-rate components in a single term avoiding, for example, treating plasticity and creep as separate response phenomena. An extensive review of existing unified theories is given and numerical methods for integrating these stiff time-temperature-dependent constitutive equations are discussed. Two particular models, those developed by Bodner and Partom and by Walker, were selected for more detailed development and evaluation against experimental tensile, creep and cyclic strain tests on specimens of a cast nickel base alloy, B19000+Hf. Initial results comparing computed and test results for tensile and cyclic straining for temperature from ambient to 982 C and strain rates from 10(exp-7) 10(exp-3) s(exp-1) are given. Some preliminary date correlations are presented also for highly non-proportional biaxial loading which demonstrate an increase in biaxial cyclic hardening rate over uniaxial or proportional loading conditions. Initial work has begun on the implementation of both constitutive models in the MARC finite element computer code.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-174718 , SWRI-06-7576/13 , NAS 1.26:174718
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  • 88
    Publication Date: 2016-06-07
    Description: The technology required to design and develop advanced commercial, conventional-takeoff-and-landing aircraft engines with significantly lower pollutant exhaust emissions levels than those of current-technology engines was generated and demonstrated. The target pollutant emissions reductions in tests of an advanced commercial aircraft turbofan engine were attained by developing advanced combustor designs. This technology is intended to be applicable to advanced military aircraft engines. The primary focus was on reducing the levels of the gaseous pollutant emissions.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Lewis Res. Center Aircraft Eng. Emissions; p 37-58
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  • 89
    Publication Date: 2016-06-07
    Description: Emissions of air pollutants from aircraft were investigated in order to determine: (1) the extent to which such emissions affect air quality in air quality control regions throughout the United States; and (2) the technological feasibility of controlling such emissions. The basic information supporting the need for aircraft emissions standards is summarized. The EPA ambient air quality standards are presented. Only the primary (health related) standards are shown. Of the six pollutants, only the first three, carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides, are influenced significantly by aircraft.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Lewis Res. Center Aircraft Eng. Emissions; p 1-17
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  • 90
    Publication Date: 2016-06-07
    Description: Methods used by airlines, with the assistance of the engine manufacturers to achieve control over the type of problems which lead to uncontained failure and avoid many potential problems are discussed.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: MIT An Assessment of Technol. for Turbojet Engine Rotor Failures; p 413-418
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  • 91
    Publication Date: 2016-06-07
    Description: A disk crack detector was developed and applied to a small military engine for use as a flight-line turbine crack monitor. The system consists of an eddy current type sensor and its cables within the engine, external connecting cables, and a remotely located electrical capacitance-conductance bridge and signal analyzer. As the turbine spins, the rotor is monitored by the sensor for radial surface cracks emanating from the interblade region of the rotor.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: MIT An Assessment of Technol. for Turbojet Engine Rotor Failures 383-388 (SEE N78-10068 01-07)
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  • 92
    facet.materialart.
    Unknown
    In:  CASI
    Publication Date: 2016-06-07
    Description: A key ingredient in the establishment of safe life times for critical components is the means of reliably detecting flaws which may potentially exist. Currently used nondestructive evaluation procedures are successful in detecting life limiting defects; however, the development of automated and computer aided NDE technology permits even greater assurance of flight safety.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: MIT An Assessment of Technol. for Turbojet Engine Rotor Failures; p 369-382
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  • 93
    facet.materialart.
    Unknown
    In:  CASI
    Publication Date: 2016-06-07
    Description: Major rotor design criteria are discussed with particular emphasis on those aspects of rotor design that ensure long life component integrity. Dynamic considerations, that necessitate tuning of bladed disk and seal assemblies to avoid excessive vibratory stress at both design and off-design conditions are reviewed as well as low cycle fatigue considerations, which have resulted in detailed analysis procedures to establish part temperature and stress variation throughout an operating cycle and extensive specimen and component fatigue testing to establish safe cyclic operating limits. The frequency, size, and behavior of intrinsic material defects were investigated. Manufacturing process improvements, including the application of increasingly sophisticated inspection techniques and quality control procedures are reviewed in light of their impact on component durability.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: MIT An Assessment of Technol. for Turbojet Engine Rotor Failures; p 331-346
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  • 94
    Publication Date: 2016-06-07
    Description: Published results on rotor burst containment with single materials, and on body armor using composite materials were used to establish a set of hypotheses about what variables might control the design of a weight-efficient protective device. Based on modern concepts for the design and analysis of small optimum seeking experiments, a particular experiment for evaluating the hypotheses and materials was designed. The design and methods for the analysis of results are described. The consequence of such hypotheses is that the device should consist of as many as four concentric rings, each to consist of a material uniquely chosen for its position in the penetration sequence.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: MIT An Assessment of Technol. for Turbojet Engine Rotor Failures; p 295-330
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  • 95
    facet.materialart.
    Unknown
    In:  CASI
    Publication Date: 2016-06-07
    Description: More realistic guideline data must be developed for use in aircraft design in order to comply with recent changes in British civil airworthiness requirements. Unrealistically pessimistic results were obtained when the methodology developed during the Concorde SST certification program was extended to assess catastrophic risks resulting from uncontained engine rotors.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: MIT An Assessment of Technol. for Turbojet Engine Rotor Failures; p 45-63
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  • 96
    Publication Date: 2016-06-07
    Description: Sections of the U.S. Airworthiness Standards which contribute to rotor integrity are explored. Reports published under NASA's Rotor Burst Protection program are included in current FAA studies to determine the weight penalty for two different levels of increased containment, and the penalty associated with protecting critical structure and systems, the passenger cabin, and the flight deck by strategic location of armor shields or deflector plates. Findings of the two studies will be used to propose revisions to regulations to reduce uncontained rotor failures.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: MIT An Assessment of Technol. for Turbojet Engine Rotor Failures; p 1-9
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  • 97
    facet.materialart.
    Unknown
    In:  CASI
    Publication Date: 2016-06-07
    Description: A brief discussion of digital jet engine control systems is given. Performance tests, systems integration, and redundancy are discussed.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Langley Research Center NASA Aircraft Controls Research, 1983; p 585-592
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  • 98
    Publication Date: 2016-06-07
    Description: Two programs are described which involve the application of advanced control techniques to the design of engine control algorithms. Multivariable control theory is used in the F100 MVCS (multivariable control synthesis) program to design controls which coordinate the control inputs for improved engine performance. A systematic method for handling a complex control design task is given. Methods of analytical redundancy are aimed at increasing the control system reliability. The F100 DIA (detection, isolation, and accommodation) program, which investigates the uses of software to replace or augment hardware redundancy for certain critical engine sensor, is described.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Langley Research Center NASA Aircraft Controls Research, 1983; p 429-442
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  • 99
    Publication Date: 2016-06-07
    Description: This project concerns the effects of cooling jets on the velocity and temperature fields in a compact reverse flow combustor. The work is motivated by the need to limit the temperatures of post combustion gases in jet engines to values within the endurance capabilities of turbine blades. The application requires not only that the temperature be kept sufficiently low but also that a suitably tailored temperature profile be provided at the combustor exit, with higher temperatures generally permissible at the blade tip than at the blade root because of higher centrifugal loads at the root. Flows in reverse flow combustor accelerate both longitudinally because of area changes and transversely because of flow turning. The current project started with flow visualization experiments in water, using aqueous solutions of zinc bromide to model the relatively higher density of cooling jets.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Lewis Research Center Combust. Fundamentals Res.; p 153-162
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  • 100
    Publication Date: 2019-06-28
    Description: Measurements and analysis limited to the dilute portions of turbulent evaporating sprays, injected into a still air environment were completed. Mean and fluctuating velocities and Reynolds stress were measured in the continuous phase. Liquid phase measurements included liquid mass fluxes, drop sizes and drop size and velocity correlation. Initial conditions needed for model evaluation were measured at a location as close to the injector exit as possible. The test sprays showed significant effects of slip and turbulent dispersion of the discrete phase. The measurements were used to evaluate three typical models of these processes: (1) a locally homogeneous flow (LHF) model, where slip between the phases were neglected; (2) a deterministic separated flow (DSF) model, where slip was considered but effects of drop dispersion by turbulence were ignored; and (3) a stochastic separated flow (SSF) model, where effects of interphase slip and turbulent dispersion were considered using random-walk computations for drop motion. For all three models, a k-epsilon model as used to find the properties of the continuous phase. The LHF and DSF models did not provide very satisfactory predictions for the present measurements. In contrast, the SSF model performed reasonably well--with no modifications in the prescription of eddy properties from its original calibration.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-174760 , NAS 1.26:174760
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