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  • Other Sources  (618)
  • AIRCRAFT PROPULSION AND POWER  (618)
  • 2000-2004
  • 1980-1984  (401)
  • 1975-1979  (217)
  • 1960-1964
  • 1925-1929
  • 1984  (182)
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  • Other Sources  (618)
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  • 2000-2004
  • 1980-1984  (401)
  • 1975-1979  (217)
  • 1960-1964
  • 1925-1929
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  • 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
    Publication Date: 2006-03-02
    Description: A preliminary investigation into the use of modern control theory for the design of controls for a supersonic inlet is described. In particular, the task of controlling a mixed-compression supersonic inlet is formulated as a linear optimal stochastic control and estimation problem. An inlet can exhibit an undesirable instability due to excessive inlet normal shock motion. For the optimal control formulation of the inlet problem, a non quadratic performance index, which is equal to the expected frequency of inlet unstarts, is used. This physically meaningful performance index is minimized for a range of inlet disturbance and measurement noise covariances.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA, Washington Fourth Inter-Center Control Systems Conf.; p 323-335
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  • 7
    Publication Date: 2006-02-28
    Description: Results of experimental investigations to control a supersonic mixed-compression inlet coupled to a turbojet engine are presented. Special instrumentation and servoactuators were developed to have sufficiently fast dynamic response so that basic propulsion system dynamics were the main limitation to controllability. In some cases servoactuator input signals were electronically limited to simulate moderate performance flight hardware.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA, Washington Fourth Inter-Center Control Systems Conf.; p 299-321
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  • 8
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    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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  • 9
    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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  • 10
    Publication Date: 2011-08-18
    Description: The Quiet Short-Haul Research Aircraft (QSRA) was designed as research aircraft for investigating terminal-area operations with an advanced propulsive-lift aircraft. The QSRA is a modified De Havilland C-8 Buffalo. The modification to the C-8 consisted of adding a new swept wing with four top-mounted Lycoming YF-102 turbofan engines to provide high levels of propulsive-lift through upper-surface blowing. The state of the art has reached the point where consideration can be given to various applications, including military transport aircraft, civil transports, and business jets. Attention is also given to a ground attack plane with QSRA, the payload advantage resulting from applying propulsive-life technology, and aspects of takeoff performance
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Astronautics and Aeronautics; 19; Apr. 198
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  • 11
    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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  • 12
    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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  • 13
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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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  • 14
    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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  • 15
    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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  • 16
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    Publication Date: 2011-08-17
    Description: The current status of the problem of gas turbine engine emissions is reviewed. Presently promulgated EPA standards and their implications for aircraft gas turbines are discussed. The progress and status of emissions reduction technology programs and other efforts which have emphasized advanced combustor technology are reviewed in detail. Also examined are those efforts underway to determine the emissions floor and incorporate those techniques into practical combustors of the future.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Progress in Energy and Combustion Science; 4; 2, 19; 1978
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  • 17
    Publication Date: 2011-08-17
    Description: The noise-generating region of a suppressed turbojet exhaust is studied by cross-correlating static pressure fluctuations within the exhaust with far-field sound for Mach numbers up to 0.99, using a 31-tube nozzle having an area ratio of 3.1. Measurements made with an unsuppressed turbojet exhaust having an equivalent area ratio and operating under effectively equal thrust loads serve as the experimental control. Static pressure-level measurements, made with a calibrated high-temperature acoustically damped probe tube, show that noise suppression by multitube nozzles results from reduced turbulence levels. The maximum fluctuating static-pressure level in the unsuppressed turbojet exhaust is typically 5-6 dB higher than static-pressure levels in the suppressed exhaust under conditions of effectively equal static thrust. This suggests that the turbulence intensity in the multitube suppressor flow is reduced in excess of 20% compared with the unsuppressed jet exhaust.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Acoustical Society of America; vol. 63
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  • 18
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    Publication Date: 2011-08-17
    Description: NASA aims at developing propulsion technology to reduce the fuel consumption of present engines by 5%, that of new engines of the late 1980s by at least 12%, and that of an advanced early 1990s turboprop by an additional 15%. This paper reviews three separate NASA programs which take up these aims. They are, respectively, Engine Component Improvement, Energy Efficient Engine, and Advanced Turboprops.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Astronautics and Aeronautics; 16; July-Aug
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  • 19
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    Publication Date: 2011-08-17
    Description: The market place is examined for general aviation aircraft into the 1980's. The visible constraints that engine manufacturers must face regardless of the type of cycle are indicated.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Lewis Res. Center The Rotary Combust. Engine; p 175-186
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  • 20
    Publication Date: 2011-08-17
    Description: The development of light aircraft with special emphasis on modern propulsion systems and production is discussed in terms of the application of rotary engines to aircraft. Emphasis is placed on the integrated ducted-fan propulsion system using rotary engines.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Lewis Res. Center The Rotary Combust. Engine; p 109-122
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  • 21
    Publication Date: 2011-08-17
    Description: Rotary engines with a chamber volume of 750 cc as a two rotor automotive powerplant, called KKM 871 are described. This engine is compared to a 3 liter or 183 cubic inch, six-cylinder reciprocating engine. Emphasis is placed on exhaust emission control and fuel economy.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Lewis Res. Center The Rotary Combust. Engine 85-107 (SEE N79-15961 07-07)
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  • 22
    Publication Date: 2011-08-17
    Description: The development of the rotary engine as a viable power plant capable of wide application is reviewed. Research results on the stratified charge engine with direct chamber injection are included. Emission control, reduced fuel consumption, and low noise level are among the factors discussed in terms of using the rotary engine in general aviation aircraft.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Lewis Res. Center The Rotary Combust. Engine; p 123-174
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  • 23
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    Publication Date: 2011-08-17
    Description: Progress in the development of rotary engines which use a thermal reactor as the primary part of the exhaust emission control system is reviewed. Possibilities of further improvements in fuel economy of future rotary engines are indicated.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Lewis Res. Center The Rotary Combust. Engine; p 37-84
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  • 24
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    Publication Date: 2011-08-17
    Description: A review is presented of nonturbine general aviation engine programs underway at the NASA-Lewis Research Center. The program encompasses conventional, lightweight diesel, and rotary engines. Its three major thrusts are: (1) reduced SFC's; (2) improved fuels tolerance; and (3) reducing emissions. Current and planned future programs in such areas as lean operation, improved fuel management, advanced cooling techniques, and advanced engine concepts, are described. These are expected to lay the technology base, by the mid to latter 1980's, for engines whose total fuel costs are as much as 30% lower than today's conventional engines.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: The Rotary Combust. Engine; p 13-35
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  • 25
    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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  • 26
    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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  • 27
    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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  • 28
    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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  • 29
    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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  • 30
    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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  • 31
    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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  • 32
    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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  • 33
    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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  • 34
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    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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  • 35
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    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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  • 36
    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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  • 37
    Publication Date: 2016-06-07
    Description: The status of research efforts to apply low to intermediate temperature composite materials and advanced high temperature materials to engine components is reviewed. Emerging materials technologies and their potential benefits to aircraft gas turbines were emphasized. The problems were identified, and the general state of the technology for near term use was assessed.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Langley Res. Center CTOL Transport Technol., 1978; p 187-204
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  • 38
    Publication Date: 2016-06-07
    Description: Progress in the development of combustor technology to meet the standards for the allowable pollutant emission levels of aircraft gas turbine engines is reported. The high-bypass-ratio turbofan engines which power the large commercial aircraft were emphasized along with efforts to reduce emission for near term applications. Recommendations for continuing research to reduce emissions to meet far term needs are given.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Langley Res. Center CTOL Transport Technol., 1978; p 205-216
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  • 39
    Publication Date: 2016-06-07
    Description: Research is reviewed in the following areas: turboprop powered transport aircraft; wind tunnel aerodynamic and acoustics tests of model propellers; turboprop maintenance; and wind tunnel tests on airframe-turboprop interactions. Continued development of the technology for advanced turboprop transport was emphasized.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Langley Res. Center CTOL Transport Technol., 1978; p 139-166
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  • 40
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    In:  CASI
    Publication Date: 2016-06-07
    Description: Turbofan engine noise research relevant to conventional aircraft is discussed. In the area of fan noise, static to flight noise differences were discussed and data were presented for two different ways of simulating flight behavior. Experimental results from a swept rotor fan design are presented which show that this concept has potential for reducing the multiple-pure-tone or buzz-saw noise related to the shock waves on a fan operating at supersonic tip speeds. Acoustic suppressor research objectives centered around the effect of the wave system generated by the fan stage that is the input to the treatment. A simplifying and unifying parameter, mode cutoff ratio was described. Results are presented which show that suppressor performance can be improved if the input wave is more precisely described. In jet noise, calculated results showing the potential noise reduction from the use of internal mixer nozzles rather than separate flow nozzles are presented.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Langley Res. Center CTOL Transport Technol., 1978; p 167-185
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  • 41
    Publication Date: 2016-06-07
    Description: The characteristics and systems benefits of an energy efficient engine (E3) suitable for use on advanced subsonic transport aircraft were determined. Relative to a current CF6-50C engine, the following benefits were estimated: 14.4% reduction in installed cruise specific fuel consumption, and a reduction in direct operating cost of more than 5%. The advanced technology E3 system would also permit: compliance with FAR 36 (1977) noise limits, and compliance with 1981 EPA emission standards.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Langley Res. Center CTOL Transport Technol., 1978; p 111-138
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  • 42
    Publication Date: 2016-06-07
    Description: A mixed exhaust, direct drive fan turbofan configuration was selected from four candidates. This choice was based on its ability to exceed study goals of 12% lower thrust specific fuel consumption and 5% lower direct operating cost by the 1990's with commercially acceptable technical risk and relative mechanical simplicity. The evaluation leading to configuration selection is discussed. Necessary technology advancements are identified and related to the goals.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Langley Res. Center CTOL Transport Technol., 1978; p 89-110
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  • 43
    Publication Date: 2016-06-07
    Description: A feasibility analysis screening method for predicting the airline acceptance of a proposed engine performance improvement modification was developed. Technical information derived from available test data and analytical models is used along with conceptual/preliminary designs to establish the predicted performance improvement, weight and installation characteristics, the cost for new production and retrofit, maintenance cost and qualitative characteristics of the performance improvement concepts being evaluated. These results are used to arrive at the payback period, which is the time required for an airline to recover the investment cost of concept implementation, and to predict the amount of fuel saved by a performance improvement concept. The assumptions used to calculate the payback period and fuel saved are discussed. A summary of the results when the screening method is applied is presented for several representative JT8D and JT9D performance improvement concepts. An example of the input information used to develop the summary results is shown.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Langley Res. Center CTOL Transport Technol., 1978; p 79-80
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  • 44
    facet.materialart.
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    In:  CASI
    Publication Date: 2016-06-07
    Description: Potential CF6 engine performance improvements directed at reduced fuel consumption were identified and screened relative to airline acceptability and are reviewed. The screening process developed to provide evaluations of fuel savings and economic factors including return on investment and direct operating cost is described. In addition, assessments of development risk and production potential are made. Several promising concepts selected for full-scale development based on a ranking involving these factors are discussed.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Langley Res. Center CTOL Transport Technol., 1978; p 59-78
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  • 45
    facet.materialart.
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    In:  CASI
    Publication Date: 2016-06-07
    Description: Technology for fuel-efficient subsonic CTOL transport aircraft is discussed. The engine component improvement project, the energy efficient engine project, and the advanced turboprop project are included. The overall goals and objectives of each project are reviewed and the approach and schedule for accomplishing these project goals and objectives are given.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Langley Res. Center CTOL Transport Technol., 1978; p 9-23
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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: 2017-10-02
    Description: The factors affecting the helicopter market for the past, present, and future are reviewed. Acquisition cost, mission reliability, life cycle cost and civil and military aspects are reviewed. The potential for advanced vehicle configurations with substantial improvements in energy efficiency, operating economics, and characteristics to satisfy the demands of the future market are identified. Advanced propulsion systems required to support these vehicle configurations and the component technology for the engine systems are discussed. The selection of components in areas of economics and efficiency is considered.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AGARD Helicopter Propulsion Systems; 12 p
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  • 48
    Publication Date: 2017-10-02
    Description: The extent and magnitude of performance deterioration of the Pratt and Whitney JT9D, and the General Electric CF6 engine models is presented. Overall engine and contributing module performance deterioration with respect to flight cycles and/or time are analyzed. The overall engine performance deterioration analyses are based on data obtained from historical records, special engine tests, and tests for specific effects. Hardware inspection data from overhaul shops and special module tests are the basis for the modular performance deterioration data used in the analyses. Various damage mechanisms such as seal rubs, erosion, surface roughness and thermal distortion, and how they contribute to performance deterioration are included in the modular analyses. Results indicate that early performance deterioration occurring within the first few flights of these engines is less than 1 percent in cruise specific fuel consumption (SFC), that it is event oriented, and that it is the result of increased blade tip clearances. This performance deterioration gradually increases to about 2.5 to 3.0 percent (including the initial short term deterioration) after 2500 to 3000 flights where increased blade tip clearances, airfoil quality degradation, and thermal distortion are the contributing causes.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AGARD Turbine Engine Testing; 14 p
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  • 49
    facet.materialart.
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    In:  CASI
    Publication Date: 2017-10-02
    Description: Gas path seals are discussed with emphasis on sealing clearance effects on engine component efficiency, compressor pressure ratio, and stall margin. Various case-rotor relative displacements, which affect gas path seal clearances, are identified. Forces produced by nonuniform sealing clearances and their effect on rotor stability are examined qualitatively, and recent work on turbine-blade-tip sealing for high temperatures is described. The need for active clearance control and for engine structural analysis is discussed. The functions of the internal-flow system and its seals are reviewed.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AGARD Seal Technol. in Gas Turbine Eng.; 41 p
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  • 50
    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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  • 51
    facet.materialart.
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    In:  CASI
    Publication Date: 2016-06-07
    Description: The expected aerodynamic effects of a propfan installed on a thick supercritical wing are summarized qualitatively. Nacelle/wing and jet interactions, slipstream incremental velocity, nonuniform inflow, and swirl loss recovery are discussed.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Langley Research Center Advan. Aerodyn. and Active Controls; p 171-181
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  • 52
    Publication Date: 2016-06-07
    Description: A systematic approach to developing an engine monitoring system (EMS) is outlined. An extensive shopping list of EMS capabilities and benefits are included. A team approach to developing an EMS is emphasized with a description of the responsibilities of each team member.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Lewis Res. Center Aircraft Engine Diagnostics; p 377-380
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  • 53
    Publication Date: 2016-06-07
    Description: The performance monitoring aspect of maintenance, characteristic of the engine health monitoring system are discussed. An overview of the system activities is presented and a summary of programs for improved monitoring in the 1980's are discussed.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Lewis Res. Center Aircraft Engine Diagnostics; p 323-340
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  • 54
    facet.materialart.
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    In:  CASI
    Publication Date: 2016-06-07
    Description: Operational evaluations of engine monitoring systems (EMS) are discussed. Options for each required EMS phase are reviewed along with the guidance provided for EMS on new systems.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Lewis Res. Center Aircraft Engine Diagnostics; p 209-224
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  • 55
    facet.materialart.
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    In:  CASI
    Publication Date: 2016-06-07
    Description: An advanced blade/shroud system designed to maintain close clearance between blade tips and turbine shrouds and at the same time, be resistant to environmental effects including high temperature oxidation, hot corrosion, and thermal cycling is described. Increased efficiency and increased blade life are attained by using the advanced blade tip seal system. Features of the system include improved clearance control when blade tips preferentially wear the shrouds and a superior single crystal superalloy tip. The tip design, joint location, characterization of the single crystal tip alloy, the abrasive tip treatment, and the component and engine test are among the factors addressed. Results of wear testing, quality control plans, and the total manufacturing cycle required to fully process the blades are also discussed.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Lewis Res. Center Aircraft Engine Diagnostics; p 137-152
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  • 56
    Publication Date: 2016-06-07
    Description: Research efforts to reduce the dependence of the aerospace industry on strategic metals, such as cobalt (Co), columbium (Cb), tantalum (Ta), and chromium (Cr), by providing the materials technology needed to minimize the strategic metal content of critical aerospace components for gas turbine engines are addressed. Thrusts in three technology areas are identified: near term activities in the area of strategic element substitution; intermediate-range activities in the area of materials processing; and long term, high risk activities in the area of 'new classes' of high temprature metallic materials. Specifically, the role of cobalt in nickel-base and cobalt-base superalloys vital to the aerospace industry is examined along with the mechanical and physical properties of intermetallics that will contain a minimum of the stragetic metals.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Aircraft Engine Diagnostics; p 189-207
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  • 57
    Publication Date: 2016-06-07
    Description: Past diagnostics studies revealed the primary causes of performance deterioration of high by-pass turbofan engines to be flight loads, erosion, and thermal distortion. The various types of airplane loads that are imposed on the engine throughout the lifetime of an airplane are examined. These include flight loads from gusts and maneuvers and ground loads from takeoff, landing, and taxi conditions. Clarification is made in definitions of the airframer's limit and ultimate design loads and the engine manufacturer's operating design loads. Finally, the influence of these loads on the propulsion system structures is discussed.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Lewis Res. Center Aircraft Engine Diagnostics; p 175-188
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  • 58
    Publication Date: 2016-06-07
    Description: An understanding of the mechanisms of deterioration is essential in order that features to counteract performance degradation can be built into the basic design of an engine and nacelle. Furthermore, the interpretation must be continued in service for effective feedback to provide modifications which may be necessary in maintaining a satisfactory performance retention program. The in service assessment must be accurate as to magnitude and causes and this requires consideration of: (1) the powerplant as a complete entity, i.e., the engine components and nacelle including the thrust reverser; (2) measurement of performance in flight rather than by sole reliance on the scaling of test cell data to flight conditions (although some correlation should be possible); and (3) the relationship of engine parts condition to overhaul performance and in flight deterioration level of that engine. These aspects are addressed by consideration of the RB211 engine in service in both the Lockheed L1011 Tristar and Boeing 747 aircraft.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Lewis Res. Center Aircraft Engine Diagnostics; p 83-102
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  • 59
    Publication Date: 2016-06-07
    Description: In the CF6 Jet Engine Diagnostics Program the causes of performance degradation were determined for each component of revenue service engines. It was found that a significant contribution to performance degradation was caused by increased airfoil tip radial clearances in the high pressure compressor and turbine areas. Since the influence of these clearances on engine performance and fuel consumption is significant, it is important to accurately establish these relatonships. It is equally important to understand the causes of clearance deterioration so that they can be reduced or eliminated. The results of factory engine tests run to enhance the understanding of the high pressure compressor and turbine clearance effects on performance are described. The causes of clearance deterioration are indicated and potential improvements in clearance control are discussed.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Lewis Res. Center Aircraft Engine Diagnostics; p 19-42
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  • 60
    facet.materialart.
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    In:  CASI
    Publication Date: 2016-06-07
    Description: The attractive performance retention characteristics of the JT8D engine are described. Because of its moderate bypass ratio and turbine temperature, and stiff structural design, the performance retention versus flight cycles of the JT8D engine sets a standard that is difficult for other engines to equal. In addition, the significant benefits of refurbishment of the JT8D engine are presented. Cold section refurbishment offers thrust specific fuel consumption improvements of up to 2 percent and payback in less than a year, making a very attractive investment option for the airlines.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Lewis Res. Center Aircraft Engine Diagnostics; p 63-81
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  • 61
    facet.materialart.
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    In:  CASI
    Publication Date: 2016-06-07
    Description: A summary of the activities which led to defining deterioration rates of the CF6 family of engines, a description of what was learned, and an identification of means of conserving fuel based upon the program findings are presented. The program to define the deterioration levels and modes for the CF6 family of engines involved four distinct phases: analysis of inbound engine test results, analysis of airline cruise data, analysis of airline test cell data resulting from testing of refurbished engines, and inspection of engine hardware.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Lewis Res. Center Aircraft Engine Diagnostics; p 1-17
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  • 62
    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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  • 63
    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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  • 64
    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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  • 65
    facet.materialart.
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    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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  • 66
    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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  • 67
    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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  • 68
    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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  • 69
    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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  • 70
    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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  • 71
    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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  • 72
    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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  • 73
    facet.materialart.
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    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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  • 74
    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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  • 75
    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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  • 76
    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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  • 77
    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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  • 78
    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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  • 79
    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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  • 80
    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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  • 81
    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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  • 82
    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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  • 83
    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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  • 84
    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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  • 85
    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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  • 86
    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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  • 87
    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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  • 88
    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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  • 89
    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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  • 90
    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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  • 91
    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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  • 92
    Publication Date: 2017-10-02
    Description: Advanced materials, coatings, and cooling technology is assessed in terms of improved aircraft turbine engine performance. High cycle operating temperatures, lighter structural components, and adequate resistance to the various environmental factors associated with aircraft gas turbine engines are among the factors considered. Emphasis is placed on progress in development of high temperature materials for coating protection against oxidation, hot corrosion and erosion, and in turbine cooling technology. Specific topics discussed include metal matrix composites, superalloys, directionally solidified eutectics, and ceramics.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AGARD High Temp. Probl. in Gas Turbine Eng.; 31 p
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  • 93
    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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  • 94
    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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  • 95
    Publication Date: 2016-06-07
    Description: The hardware and software development of the A-10/TF34 turbine engine monitoring system (TEMS) is described. The operation and interfaces of the A-10/TF34 TEMS hardware are discussed with particular emphasis on function, capabilities, and limitations. The TEMS data types are defined and the various data acquisition modes are explained. Potential data products are also discussed.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Lewis Res. Center Aircraft Engine Diagnostics; p 271-283
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  • 96
    Publication Date: 2016-06-07
    Description: In order to evaluate the potential effectiveness of coatings in limiting erosive damage to compressor airfoils, an effort was initiated to evaluate candidate coatings for substrate alloys typically used in commercial engine high compressor blades. Laboratory and rig erosion testing of plasma deposited and diffusion coatings described in this paper have shown the potential of a two to four fold improvement in erosion life. The selective application of these coatings to approximately the outer third of the airfoil avoids coating the fatigue critical region of the blade, thus providing erosion resistance potentially without compromising the fatigue strength of the blade. Both the plasma and the diffusion coatings also offer the advantage of low initial cost and a multi-source production base.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Lewis Res. Center Aircraft Engine Diagnostics; p 109-117
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  • 97
    Publication Date: 2016-06-07
    Description: The on condition program is described in terms of its effectiveness as a maintenance tool both at the line station as well as at home base by the early detection of engine faults, erroneous instrumentation signals and by verification of engine health. The system encompasses all known methods from manual procedures to the fully automated airborne integrated data system.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Lewis Res. Center Aircraft Engine Diagnostics; p 341-356
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  • 98
    facet.materialart.
    Unknown
    In:  CASI
    Publication Date: 2016-06-07
    Description: The operation and implementation of the aircraft integrated data system AIDS are described. The system is described as an engineering tool with strong emphasis on analysis of recorded information. The AIDS is primarily directed to the monitoring of parameters related to: the safety of the flight; the performance of the aircraft; the performance of the flight guidance system; and the performance and condition of the engines. The system provide short term trend analysis on a trend chart that is updated by the flight engineer on every flight that lasts more than 4 flight hours. Engine data prints are automatically presented during take-off and in the case of limit excedance, e.g., the print shows an automatically reported impending hotstarts on engine nr. 1. Other significant features are reported.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Lewis Res. Center Aircraft Engine Diagnostics; p 285-310
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  • 99
    facet.materialart.
    Unknown
    In:  CASI
    Publication Date: 2016-06-07
    Description: An engine diagnostic system, proposed for the F100 engine, was tested in five specially modified Tactical Air Command F-15 aircraft during a 16-month flight evaluation. After more than 3300 engine operating hours encompassing almost 900 flights during the flight evaluation, these aircraft provided a data base, still being analyzed, that has shown successful demonstration of the original functional characteristics. Four general design requirements, recording engine operating time/low cycle fatigue event detection, engine trim, and trend and performance data collection were demonstrated. Also, validation of maintenance actions taken and indicated needed maintenance were successfully demonstrated.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Lewis Res. Center Aircraft Engine Diagnostics; p 225-242
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  • 100
    Publication Date: 2016-06-07
    Description: An overview of research to develop and improve the accuracy of current analysis methods so that increased durability can be designed into future engines is presented. Emphasis is placed on improved accuracy in life prediction. Component design, including description of the thermal and aerodynamic environments, the material's mechanical response, the interactions between environmental and structural response, and high temperature instrumentation capable of measuring near-engine environment effects are addressed. Component tests, improved modeling of the physical phenomena, and tests to verify the proved models are also discussed.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Aircraft Engine Diagnostics; p 153-173
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