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  • Other Sources  (1,052)
  • AIRCRAFT PROPULSION AND POWER  (1,052)
  • 1980-1984  (1,052)
  • 1
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    Fuel property effects on USN gas turbine combustors (1984)
    In:  CASI
    Details
    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
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    Influence of fuel chemical properties on gas turbine combustors (1984)
    In:  CASI
    Details
    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
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    Optimization applications in aircraft engine design and test (1984)
    In:  CASI
    Details
    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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    Analytical fuel property effects: Small combustors (1984)
    In:  CASI
    Details
    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
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    Fuel property effects on USAF gas turbine engine combustors and afterburners (1984)
    In:  CASI
    Details
    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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    V/STOL propulsion control technology (1984)
    In:  Other Sources
    Details
    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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  • 7
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    Blade tip geometry - A factor in abrading sintered seal material (1984)
    In:  Other Sources
    Details
    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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  • 8
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    Tone generation by rotor-downstream strut interaction (1984)
    In:  Other Sources
    Details
    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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  • 9
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    Lateral jet injection into typical combustor flowfields (1984)
    In:  CASI
    Details
    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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  • 10
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    Aerothermal modeling program, phase 2 (1984)
    In:  CASI
    Details
    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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  • 11
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    STAEBL: Structural tailoring of engine blades, phase 2 (1984)
    In:  CASI
    Details
    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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  • 12
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    Liner environment effects study (1984)
    In:  CASI
    Details
    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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  • 13
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    Real-time Pegasus propulsion system model V/STOL-piloted simulation evaluation (1984)
    In:  Other Sources
    Details
    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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  • 14
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    Design and flight test of a Kevlar acoustic liner (1984)
    In:  Other Sources
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    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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  • 15
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    Flight effects on fan noise with static and wind-tunnel comparisons (1984)
    In:  Other Sources
    Details
    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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  • 16
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    The all-electric aircraft - A systems view and proposed NASA research Programs (1984)
    In:  Other Sources
    Details
    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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  • 17
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    Identification of multivariable high-performance turbofan engine dynamics from closed-loop data (1984)
    In:  Other Sources
    Details
    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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  • 18
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    The role of modern control theory in the design of controls for aircraft turbine engines (1984)
    In:  Other Sources
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    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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  • 19
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    Powerplant design for one-engine-inoperative operation (1984)
    In:  Other Sources
    Details
    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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  • 20
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    Investigation of mixing in a turbofan exhaust duct. II Computer code application and verification (1984)
    In:  Other Sources
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    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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  • 21
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    The coupled response of turbomachinery blading to aerodynamic excitations (1984)
    In:  Other Sources
    Details
    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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  • 22
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    Component specific modeling (1984)
    In:  CASI
    Details
    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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  • 23
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    Burner liner thermal/structural load modelling (1984)
    In:  CASI
    Details
    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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  • 24
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    Identification of multivariable high-performance turbofan engine dynamics from closed loop data (1984)
    In:  CASI
    Details
    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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  • 25
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    Engine cyclic durability by analysis and material testing (1984)
    In:  CASI
    Details
    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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  • 26
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    Simplified analytical procedures for representing material cyclic response (1984)
    In:  Other Sources
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    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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  • 27
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    Control technology for future aircraft propulsion systems (1984)
    In:  CASI
    Details
    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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  • 28
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    Airstart performance of a digital electronic engine control system on an F100 engine (1984)
    In:  CASI
    Details
    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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  • 29
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    The dynamics of a flexible bladed disc on a flexible rotor in a two-rotor system (1984)
    In:  Other Sources
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    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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  • 30
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    Aeroelastic formulations for turbomachines and propellers (1984)
    In:  Other Sources
    Details
    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.
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    Real-time in-flight thrust calculation on a digital electronic engine control-equipped F100 engine in an F-15 airplane (1984)
    In:  CASI
    Details
    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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  • 32
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    Augmentor transient capability of an F100 engine equipped with a digital electronic engine control (1984)
    In:  CASI
    Details
    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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  • 33
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    Digital electronic engine control fault detection and accommodation flight evaluation (1984)
    In:  CASI
    Details
    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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  • 34
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    Flight testing the digital electronic engine control in the F-15 airplane (1984)
    In:  CASI
    Details
    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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  • 35
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    Investigation of a nozzle instability on an F100 engine equipped with a digital electronic engine control (1984)
    In:  CASI
    Details
    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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  • 36
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    Effects of inlet distortion on a static pressure probe mounted on the engine hub in an F-15 airplane (1984)
    In:  CASI
    Details
    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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  • 37
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    F-15 digital electronic engine control system description (1984)
    In:  CASI
    Details
    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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  • 38
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    Digital electronic engine control history (1984)
    In:  CASI
    Details
    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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  • 39
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    Advanced turboprop vibratory characteristics (1984)
    In:  CASI
    Details
    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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  • 40
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    Low-cost single-crystal turbine blades, volume 2 (1984)
    In:  CASI
    Details
    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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  • 41
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    On optimal design for the blade-root/hub interface in jet engines (1984)
    In:  CASI
    Details
    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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  • 42
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    Optimization of cascade blade mistuning under flutter and forced response constraints (1984)
    In:  CASI
    Details
    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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  • 43
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    Mechanical behavior of thermal barrier coatings for gas turbine blades (1984)
    In:  CASI
    Details
    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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  • 44
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    Turbine Airfoil Deposition Models (1984)
    In:  CASI
    Details
    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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  • 45
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    Response of a small-turboshaft-engine compression system to inlet temperature distortion (1984)
    In:  CASI
    Details
    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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  • 46
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    Channel flow modeling of impingement cooling of a rotating turbine blade (1984)
    In:  CASI
    Details
    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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  • 47
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    Digital electronic engine control F-15 overview (1984)
    In:  CASI
    Details
    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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  • 48
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    Backup control airstart performance on a digital electronic engine control-equipped F100-engine (1984)
    In:  CASI
    Details
    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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  • 49
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    Flight evaluation of a hydromechanical backup control for the digital electronic engine control system in an F100 engine (1984)
    In:  CASI
    Details
    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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  • 50
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    NASA Lewis F100 engine testing (1984)
    In:  CASI
    Details
    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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    Energy Efficient Engine (E3) combustion system component technology performance report (1984)
    In:  CASI
    Details
    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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  • 52
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    Energy Efficient Engine combustor test hardware detailed design report (1984)
    In:  CASI
    Details
    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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  • 53
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    Energy Efficient Engine high pressure turbine component test performance report (1984)
    In:  CASI
    Details
    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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    Energy Efficient Engine exhaust mixer model technology report addendum; phase 3 test program (1984)
    In:  CASI
    Details
    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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  • 55
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    Constitutive modeling for isotropic materials (HOST) (1984)
    In:  CASI
    Details
    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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  • 56
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    Propulsion control technology (1984)
    In:  CASI
    Details
    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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  • 57
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    Application of advanced control techniques to aircraft propulsion systems (1984)
    In:  CASI
    Details
    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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    Dilution jet experiments in compact combustor configurations (1984)
    In:  CASI
    Details
    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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    A theoretical and experimental study of turbulent evaporating sprays (1984)
    In:  CASI
    Details
    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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  • 60
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    JT15D simulated flight data evaluation (1984)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The noise characteristics of the JT15D turbofan engine was analyzed with the objectives of: (1) assessing the state-of-art ability to simulate flight acoustic data using test results acquired in wind tunnel and outdoor (turbulence controlled) environments; and (2) predicting the farfield noise directivity of the blade passage frequency (BPF) tonal components using results from rotor blade mounted dynamic pressure instrumentation. Engine rotor tip speeds at subsonic, transonic, and supersonic conditions were evaluated. The ability to simulate flight results was generally within 2-3 dB for both outdoor and wind tunnel acoustic results. Some differences did occur in the broadband noise level and in the multiple-pure-tone harmonics at supersonic tip speeds. The prediction of blade passage frequency tone directivity from dynamic pressure measurements was accomplished for the three tip speed conditions. Predictions were made of the random and periodic components of the tone directivity. The technique for estimating the random tone component used hot wire data to establish a correlation between dynamic pressure and turbulence intensity. This prediction overestimated the tone level by typically 10 dB with the greatest overestimates occurring at supersonic conditions.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-172322 , NAS 1.26:172322
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  • 61
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    Effect of control logic modifications on airstart performance of F100 engine model derivative engines in an F-15 airplane (1984)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A series of airstarts were conducted in an F-15 airplane with two prototype Pratt and Whitney F100 Engine Model Derivative engines equipped with Digital Electronic Engine Control (DEEC) systems. The airstart envelope and the time required for airstarts were defined. Comparisons were made between the original airstart logic, and modified logic which was designed to improve the airstart capability. Spooldown airstarts with the modified logic were more successful at lower altitudes than were those with the original logic. Spooldown airstart times ranged from 33 seconds at 250 knots to 83 seconds at 175 knots. The modified logic improved the airstart time from 31% to 53%, with the most improved times at slower airspeeds. Jet fuel starter (JFS)-assisted airstarts were conducted at 7000 m and airstart times were significantly faster than unassisted airstarts. The effect of altitude on airstart times was small.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-85900 , H-1243 , NAS 1.15:85900
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  • 62
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    A theoretical and experimental study of turbulent nonevaporating sprays (1984)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Measurements and analysis limited to the dilute portions of turbulent nonevaporating 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 homogenous 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. 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. Some effects of drops on turbulence properties were observed near the dense regions of the sprays.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-174668 , NAS 1.26:174668
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  • 63
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    Detailed flow measurements in casing boundary layer of 429-meter-per-second-tip-speed two-stage fan (1984)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Detailed flow measurements between all blade rows were taken in the outer 30 percent of passage height of a two stage fan. Tabulations of the detailed flow measurements are included. Results of these measurements revealed the steep axial velocity profiles near the casing. The axial velocity profile near the casing at the rotor exists was much steeper than at the stator exits. The data also show overturning of the flow at the tip at the stator exits. The effect of mixing is shown by the redistribution of the first stage rotor exit total temperature profile as it passes through the following stator.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TP-2052 , E-219 , NAS 1.60:2052 , AVRADCOM-TR-81-C-28
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  • 64
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    Dilution jets in accelerated cross flows (1984)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Results of flow visualization experiments and measurements of the temperature field produced by a single jet and a row of dilution jets issued into a reverse flow combustor are presented. The flow in such combustors is typified by transverse and longitudinal acceleration during the passage through its bending section. The flow visualization experiments are designed to examine the separate effects of longitudinal and transverse acceleration on the jet trajectory and spreading rate. A model describing a dense single jet in a lighter accelerating cross flow is developed. The model is based on integral conservation equations, including the pressure terms appropriate to accelerating flows. It uses a modified entrainment correlation obtained from previous experiments of a jet in a cross stream. The flow visualization results are compared with the model calculations in terms of trajectories and spreading rates. Each experiment is typified by a set of three parameters: momentum ratio, density ratio and the densimetric Froude number.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-174717 , NAS 1.26:174717
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  • 65
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    Preliminary flight evaluation of F100 engine model derivative airstart capability in an F-15 airplane (1984)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A series of airstarts was conducted in an F-15 airplane with two prototype F100 engine model derivative (EMD) engines equipped with digital electronic engine control (DEEC) systems. The airstart envelope and time required for airstarts were defined. The success of an airstart is most heavily dependent on airspeed. Spooldown airstarts at 200 knots and higher were all successful. Spooldown airstart times ranged from 53 sec at 250 knots to 170 sec at 175 knots. Jet fuel starter (JFS) assisted airstarts were conducted at 175 knots at two altitudes, and airstart times were 50 and 60 sec, significantly faster than unassisted airstart. The effect of altitude on airstarts was small. In addition, the airstart characteristics of the two test engines were found to closely resemble each other. The F100 EMD airstart characteristics were very similar to the DEEC equipped F100 engine tested previously. Finally, the time required to spool down from intermediate power compressor rotor speed to a given compressor rotor speed was found to be a strong function of altitude and a weaker function of airspeed.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-86031 , H-1200 , NAS 1.15:86031
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  • 66
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    High altitude aerodynamic platform concept evaluation and prototype engine testing (1984)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A design concept has been developed for maintaining a 150-pound payload at 60,000 feet altitude for about 50 hours. A 600-pound liftoff weight aerodynamic vehicle is used which operates at sufficient speeds to withstand prevailing winds. It is powered by a turbocharged four-stoke cycle gasoline fueled engine. Endurance time of 100 hours or more appears to be feasible with hydrogen fuel and a lighter payload. A prototype engine has been tested to 40,000 feet simulated altitude. Mismatch of the engine and the turbocharger system flow and problems with fuel/air mixture ratio control characteristics prohibited operation beyond 40,000 feet. But there seems to be no reason why the concept cannot be developed to function as analytically predicted.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-58256 , S-530 , NAS 1.15:58256
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  • 67
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    Comparison of full-scale engine and subscale model performance of a mixed flow exhaust system for an energy efficient engine (E3) propulsion system (1984)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A full scale engine test of the NASA/General Electric Company (GE) Energy Efficient Engine (E3) was conducted to demonstrate the E3 engine concept and evaluate its performance. The test program, performed at the GE outdoor engine test facilities in Peebles, OH, included a detailed evaluation of the total pressure and temperature profiles at the exit of the mixed flow exhaust system to determine its mixing effectiveness. Subscale model tests of the same mixed flow exhaust system had been previously conducted at FluiDyne Engineering Corporation in Minneapolis, Minnesota as part of the GE E3 mixer aerodynamic technology development program. The scale model and full scale engine nozzle exit survey data and the calculated mixing effectiveness are compared and discussed. Results indicate the full scale engine mixing effectiveness to be five percent higher than the scale model as a result of a geometric difference and higher turbulence levels in the engne exhaust flowfield.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 84-0283
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  • 68
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    Real-time hybrid computer simulation of a small turboshaft engine and control system (1984)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The development of an analytical model of a small turboshaft engine designed for helicopter propulsion systems is described. The model equations were implemented on a hybrid computer system to provide a real time nonlinear simulation of the engine performance over a wide operating range. The real time hybrid simulation of the engine was used to evaluate a microprocessor based digital control module. This digital control module was developed as part of an advanced rotorcraft control program. After tests with the hybrid engine simulation the digital control module was used to control a real engine in an experimental program. A hybrid simulation of the engine's electrical hydromechanical control system was developed. This allowed to vary the fuel flow and torque load inputs to the hybrid engine simulation for simulating transient operation. A steady-state data and the experimental tests are compared. Analytical model equations, analog computer diagrams, and a digital computer flow chart are included.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-83579 , E-1968 , NAS 1.15:83579
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  • 69
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    Formulation of blade-flutter spectral analyses in stationary reference frame (1984)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Analytic representations are developed for the discrete blade deflection and the continuous tip static pressure fields in a stationary reference frame. Considered are the sampling rates equal to the rotational frequency, equal to blade passing frequency, and for the pressure, equal to a multiple of the blade passing frequency. For the last two rates the expressions for determining the nodal diameters from the spectra are included. A procedure is presented for transforming the complete unsteady pressure field into a rotating frame of reference. The determination of the true flutter frequency by using two sensors is described. To illustrate their use, the developed procedures are used to interpret selected experimental results.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TP-2296 , E-1888 , NAS 1.60:2296
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  • 70
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    Error reduction program: A progress report (1984)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Five finite differences schemes were evaluated for minimum numerical diffusion in an effort to identify and incorporate the best error reduction scheme into a 3D combustor performance code. Based on this evaluated, two finite volume method schemes were selected for further study. Both the quadratic upstream differencing scheme (QUDS) and the bounded skew upstream differencing scheme two (BSUDS2) were coded into a two dimensional computer code and their accuracy and stability determined by running several test cases. It was found that BSUDS2 was more stable than QUDS. It was also found that the accuracy of both schemes is dependent on the angle that the streamline make with the mesh with QUDS being more accurate at smaller angles and BSUDS2 more accurate at larger angles. The BSUDS2 scheme was selected for extension into three dimensions.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Lewis Research Center Combust. Fundamentals Res.; p 83-95
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  • 71
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    Parallel processor engine model program (1984)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The Parallel Processor Engine Model Program is a generalized engineering tool intended to aid in the design of parallel processing real-time simulations of turbofan engines. It is written in the FORTRAN programming language and executes as a subset of the SOAPP simulation system. Input/output and execution control are provided by SOAPP; however, the analysis, emulation and simulation functions are completely self-contained. A framework in which a wide variety of parallel processing architectures could be evaluated and tools with which the parallel implementation of a real-time simulation technique could be assessed are provided.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-174641 , NAS 1.26:174641 , PWA-5896-21
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  • 72
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    Turbine blade testing methods (1984)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Testing procedures which could be used to model test turbine blades are developed. The methods studied were methods which used and extended current modal testing procedures. An acoustical impacting testing method was perfected for testing small turbine blades.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-170982 , NAS 1.26:170982
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  • 73
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    Secondary flow spanwise deviation model for the stators of NASA middle compressor stages (1984)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A model of the spanwise variation of deviation for stator blades is presented. Deviation is defined as the difference between the passage mean flow angle and the metal angle at the outlet of a blade element of an axial compressor stage. The variation of deviation is taken as the difference above or below that predicted by blade element, (i.e., two-dimensional) theory at any spanwise location. The variation of deviation is dependent upon the blade camber, solidity and inlet boundary layer thickness at the hub or tip end-wall, and the blade channel aspect ratio. If these parameters are known or can be calculated, the model provides a reasonable approximation of the spanwise variation of deviation for most compressor middle stage stators operating at subsonic inlet Mach numbers.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-173360 , NAS 1.26:173360
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  • 74
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    HYTESS: A hypothetical turbofan engine simplified simulation (1984)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A users manual for a hypothetical turbofan engine simplified simulation is presented. This digital simulation exists as FORTRAN source code. The program is self-contained and was developed to offer those interested in engine dynamics and controls research an efficient, realistic, and easily used engine simulation. The engine is modeled using a state space formulation. Matrix elements within the linear state space structure are nonlinear functions of various engine variables.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-83561 , E-1940 , NAS 1.15:83561
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  • 75
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    An interactive computer code for calculation of gas-phase chemical equilibrium (EQLBRM) (1984)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A user friendly, menu driven, interactive computer program known as EQLBRM which calculates the adiabatic equilibrium temperature and product composition resulting from the combustion of hydrocarbon fuels with air, at specified constant pressure and enthalpy is discussed. The program is developed primarily as an instructional tool to be run on small computers to allow the user to economically and efficiency explore the effects of varying fuel type, air/fuel ratio, inlet air and/or fuel temperature, and operating pressure on the performance of continuous combustion devices such as gas turbine combustors, Stirling engine burners, and power generation furnaces.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-168337 , NAS 1.26:168337
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  • 76
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    CREKID: A computer code for transient, gas-phase combustion of kinetics (1984)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A new algorithm was developed for fast, automatic integration of chemical kinetic rate equations describing homogeneous, gas-phase combustion at constant pressure. Particular attention is paid to the distinguishing physical and computational characteristics of the induction, heat-release and equilibration regimes. The two-part predictor-corrector algorithm, based on an exponentially-fitted trapezoidal rule, includes filtering of ill-posed initial conditions, automatic selection of Newton-Jacobi or Newton iteration for convergence to achieve maximum computational efficiency while observing a prescribed error tolerance. The new algorithm was found to compare favorably with LSODE on two representative test problems drawn from combustion kinetics.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-83806 , E-2176 , NAS 1.15:83806
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  • 77
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    Effect of combined pressure and temperature distortion orientation on high-bypass-ratio turbofan engine stability (1984)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Total-temperature, static-pressure and total-pressure distributions were measured in the inlet duct upstream of the engine inlet and within the fan and compressor of a YTF34 turbofan engine. Free-stream and boundary layer yaw angle variations were measured between a rotable screen assembly and the engine inlet. Total pressure distortions were generated using three 180 deg extent screens and total temperature distortions were generated using a rotatable hydrogen burner. Reynolds number index upstream of the rotatable screen assembly was maintained at 0.5 (based on the undistorted sectors at station 1, the inlet flow measuring station). The engine mechanical fan speed at sea level condition was rated at 7005 rpm. The engine was tested at a corrected fan speed of 90 percent of rated condition. Yaw angle increased between the rotatable screen assembly and the engine inlet. The largest variation in free-stream and boundary layer yaw angle occurs when the combined distortions are 180 deg out-of-phase. Static-pressure distortion increased exponentially as flow approached the engine. Total-pressure distortions were attenuated between the engine inlet and the compressor exit. Total-temperature distortion persisted through the compressor for all four combined distortions investigated.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-83771 , E-2262 , NAS 1.15:83771
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  • 78
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    Analytical and experimental investigation of stator endwall countouring in a small axial-flow turbine (1984)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: An experimental and analytical investigation was conducted to determine the effect of stator endwall contouring on turbine stage performance. In this investigation three stator configurations were evaluated using a common rotor. The three stator configurations were a cylindrical endwall design and two contoured endwall designs, one having a S-shaped outer wall profile and the other having a conical-shaped outer wall profile. Experimental data were obtained over a range of equivalent speeds, total pressure ratios, and rotor tip clearances for each stator-rotor combination. Detailed analytical loss assessments were conducted to aid in the determination of the contouring effect on turbine performance.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TP-2309 , E-2050 , NAS 1.60:2309 , AVSCOM-TR-84-C-5
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    Lewis Research Center spin rig and its use in vibration analysis of rotating systems (1984)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The Lewis Research Center spin rig was constructed to provide experimental evaluation of analysis methods developed under the NASA Engine Structural Dynamics Program. Rotors up to 51 cm (20 in.) in diameter can be spun to 16,000 rpm in vacuum by an air motor. Vibration forcing functions are provided by shakers that apply oscillatory axial forces or transverse moments to the shaft, by a natural whirling of the shaft, and by an air jet. Blade vibration is detected by strain gages and optical blade-tip motion sensors. A variety of analogy and digital processing equipment is used to display and analyze the signals. Results obtained from two rotors are discussed. A 56-blade compressor disk was used to check proper operation of the entire spin rig system. A special two-blade rotor was designed and used to hold flat and twisted plates at various setting and sweep angles. Accurate Southwell coefficients have been obtained for several modes of a flat plate oriented parallel to the plane of rotation.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TP-2304 , E-1829 , NAS 1.60:2304
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  • 80
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    Investigation of the effects of pressure gradient, temperature and wall temperature ratio on the stagnation point heat transfer for circular cylinders and gas turbine vanes (1984)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Low and high pressure shock tubes were designed and constructed for the purpose of obtaining heat transfer data over a temperature range of 390 to 2500 K, pressures of 0.3 to 42 atm, and Mach numbers of 0.15 to 1.5 with and without pressure gradient. A square test section with adjustable top and bottom walls was constructed to produce the favorable and adverse pressure gradient over the flat plate with heat gages. A water cooled gas turbine nozzle cascade which is attached to the high pressure shock tube was obtained to measuse the heat flux over pressure and suction surfaces. Thin-film platinum heat gages with a response time of a few microseconds were developed and used to measure the heat flux for laminar, transition, and turbulent boundary layers. The laminar boundary heat flux on the shock tube wall agreed with Mirel's flat plate theory. Stagnation point heat transfer for circular cylinders at low temperature compared with the theoretical prediction, but for a gas temperature of 922 K the heat fluxes were higher than the predicted values. Preliminary flat plate heat transfer data were measured for laminar, transition, and turbulent boundary layers with and without pressure gradients for free-stream temperatures of 350 to 2575 K and flow Mach numbers of 0.11 to 1.9. The experimental heat flux data were correlated with the laminar and turbulent theories and the agreement was good at low temperatures which was not the case for higher temperatures.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-174667 , NAS 1.26:174667
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    Real time pressure signal system for a rotary engine (1984)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A real-time IMEP signal which is a composite of those produced in any one chamber of a three-lobed rotary engine is developed by processing the signals of four transducers positioned in a Wankel engine housing such that the rotor overlaps two of the transducers for a brief period during each cycle. During the overlap period of any two transducers, their output is compared and sampled for 10 microseconds per 0.18 degree of rotation by a sampling switch and capacitive circuit. When the switch is closed, the instantaneous difference between the value of the transducer signals is provided while with the switch open the average difference is produced. This combined signal, along with the original signal of the second transducer, is fed through a multiplexer to a pressure output terminal. Timing circuits, controlled by a crank angle encoder on the engine, determine which compared transducer signals are applied to the output terminal and when, as well as the open and closed periods of the switches.
    Keywords: AIRCRAFT PROPULSION AND POWER
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  • 82
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    Performance of a high-work low aspect ratio turbine tested with a realistic inlet radial temperature profile (1984)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Experimental results are presented for a 0.767 scale model of the first stage of a two-stage turbine designed for a high by-pass ratio engine. The turbine was tested with both uniform inlet conditions and with an inlet radial temperature profile simulating engine conditions. The inlet temperature profile was essentially mixed-out in the rotor. There was also substantial underturning of the exit flow at the mean diameter. Both of these effects were attributed to strong secondary flows in the rotor blading. There were no significant differences in the stage performance with either inlet condition when differences in tip clearance were considered. Performance was very close to design intent in both cases. Previously announced in STAR as N84-24589
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 84-1161
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  • 83
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    Heat pipe applications in aircraft propulsion (1984)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Heat pipes for improving the cycle efficiency and/or thrust-to-weight ratio of aircraft gas turbines are examined. A heat pipe employs a capillary structure, a wick, and an evacuated chamber to transfer heat between condensor and evaporator ends. Heat absorbed at the evaporator is transported to the condensor. In an aircraft, the heat pipe can be stationary or rotating, can be used for cooling stators and rotors, and is amenable to shapes such as cylinders, cones, and flat plates. Heat pipes in aircraft gas turbines can be applied for intercooling between stages, regeneration, reheat, and blade cooling. Improvements are projected in the cycle efficiency, thrust and thrust specific fuel consumption in the fanjet by using heat pipes. Consideration is also given to heat pipe heat exchangers with high axial heat transfer for stationary heat pipes and high heat transport for rotating heat pipes.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 84-1269
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  • 84
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    Determination of compressor in-stall characteristics from engine surge transients (1984)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A technique for extracting the in-stall pumping characteristics for an axial flow compressor operating in an engine system environment is developed. The technique utilzes a Hybrid computer simulation of the compressor momentum equation in which actual transient data are used to provide all terms but the desired compressor characteristic. The compressor force characteristic as a function of corrected flow and speed results from the computation. The critical problem of data filtering is addressed. Results for a compressor operating in a turbofan engine are presented and comparison is made with the conventional compressor map. The relationship of the compressor surge charcteristic with its rotating stall characteristic is explored. Initial interpretation of the measured results is presented. Previously announced in STAR as N84-22566
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 84-1206
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  • 85
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    Advanced propfan drive system characteristics and technology needs (1984)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Characteristics of a single-rotation drive system for an advanced turboprop engine are described. The gearbox is designed for a 10,000 shp three-spool, free-turbine engine and is installed in a wing-mounted nacelle. An offset gearbox from an earlier APET study provided the background for the preliminary design and benefit analysis for a 1990s advanced technology versus 1980s state-of-the-art gearbox. High efficiencies were achieved for both designs with inherently high life goals. Increases in design allowables for gears, bearings, and lubricants resulted in improvements for the 1990s design.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 84-1194
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  • 86
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    Highly integrated digital engine control system on an F-15 airplane (1984)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The highly integrated digital electronic control (HIDEC) program will demonstrate and evaluate the improvements in performance and mission effectiveness that result from integrated engine-airframe control systems. This system is being used on the F-15 airplane at the Dryden Flight Research Facility of NASA Ames Research Center. An integrated flightpath management mode and an integrated adaptive engine stall margin mode are being implemented into the system. The adaptive stall margin mode is a highly integrated mode in which the airplane flight conditions, the resulting inlet distortion, and the engine stall margin are continuously computed; the excess stall margin is used to uptrim the engine for more thrust. The integrated flightpath management mode optimizes the flightpath and throttle setting to reach a desired flight condition. The increase in thrust and the improvement in airplane performance is discussed in this paper.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 84-1259
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  • 87
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    Specification, design, and test of aircraft engine isolators for reduced interior noise (1984)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Previously cited in issue 10, p. 1377, Accession no. A83-25932
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Journal of Aircraft (ISSN 0021-8669); 21; 389-396
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  • 88
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    Identification of quasi-steady compressor characteristics from transient data (1984)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The principal goal was to demonstrate that nonlinear compressor map parameters, which govern an in-stall response, can be identified from test data using parameter identification techniques. The tasks included developing and then applying an identification procedure to data generated by NASA LeRC on a hybrid computer. Two levels of model detail were employed. First was a lumped compressor rig model; second was a simplified turbofan model. The main outputs are the tools and procedures generated to accomplish the identification.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-174685 , NAS 1.26:174685
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  • 89
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    An experimental investigation of gas jets in confined swirling air flow (1984)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The fluid dynamics of jets in confined swirling flows which is of importance to designers of turbine combustors and solid fuel ramjets used to power missiles fired from cannons were examined. The fluid dynamics of gas jets of different densities in confined swirling flows were investigated. Mean velocity and turbulence measurements are made with a one color, one component laser velocimeter operating in the forward scatter mode. It is shown that jets in confined flow with large area ratio are highly dissipative which results in both air and helium/air jet centerline velocity decays. For air jets, the jet like behavior in the tube center disappears at about 20 diameters downstream of the jet exit. This phenomenon is independent of the initial jet velocity. The turbulence field at this point also decays to that of the background swirling flow. A jet like behavior in the tube center is noticed even at 40 diameters for the helium/air jets. The subsequent flow and turbulence field depend highly on the initial jet velocity. The jets are fully turbulent, and the cause of this difference in behavior is attributed to the combined action swirl and density difference. This observation can have significant impact on the design of turbine combustors and solid fuel ramjets subject to spin.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-3832 , L-2178 , NAS 1.26:3832
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  • 90
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    Dilution jet mixing program (1984)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Parametric tests were conducted to quantify the mixing of opposed rows of jets (two-sided injection) in a confined cross flow. Results show that jet penetrations for two sided injections are less than that for single-sided injections, but the jet spreading rates are faster for a given momentum ratio and orifice plate. Flow area convergence generally enhances mixing. Mixing characteristics with asymmetric and symmetric convergence are similar. For constant momentum ratio, the optimum S/H(0) with in-line injections is one half the optimum value for single sided injections. For staggered injections, the optimum S/H(0) is twice the optimum value for single-sided injection. The correlations developed predicted the temperature distributions within first order accuracy and provide a useful tool for predicting jet trajectory and temperature profiles in the dilution zone with two-sided injections.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-174624 , NAS 1.26:174624 , GARRETT-21-4804
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  • 91
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    Fabrication development for ODS-superalloy, air-cooled turbine blades (1984)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: MA-600 is a gamma prime and oxide dispersion strengthened superalloy made by mechanical alloying. At the initiation of this program, MA-6000 was available as an experimental alloy only and did not go into production until late in the program. The objective of this program was to develop a thermal-mechanical-processing approach which would yield the necessary elongated grain structure and desirable mechanical properties after conventional press forging. Forging evaluations were performed to select optimum thermal-mechanical-processing conditions. These forging evaluations indicated that MA-6000 was extremely sensitive to die chilling. In order to conventionally hot forge the alloy, an adherent cladding, either the original extrusion can or a thick plating, was required to prevent cracking of the workpiece. Die design must reflect the requirement of cladding. MA-6000 was found to be sensitive to the forging temperature. The correct temperature required to obtain the proper grain structure after recrystallization was found to be between 1010-1065 C (1850-1950 F). The deformation level did not affect subsequent crystallization; however, sharp transition areas in tooling designs should be avoided in forming a blade shape because of the potential for grain structure discontinuities. Starting material to be used for forging should be processed so that it is capable of being zone annealed to a coarse elongated grain structure as bar stock. This conclusion means that standard processed bar materials can be used.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-174650 , NAS 1.26:174650 , ER-8162-F
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  • 92
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    Direct simulations of chemically reacting turbulent mixing layers (1984)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The report presents the results of direct numerical simulations of chemically reacting turbulent mixing layers. The work consists of two parts: (1) the development and testing of a spectral numerical computer code that treats the diffusion reaction equations; and (2) the simulation of a series of cases of chemical reactions occurring on mixing layers. The reaction considered is a binary, irreversible reaction with no heat release. The reacting species are nonpremixed. The results of the numerical tests indicate that the high accuracy of the spectral methods observed for rigid body rotation are also obtained when diffusion, reaction, and more complex flows are considered. In the simulations, the effects of vortex rollup and smaller scale turbulence on the overall reaction rates are investigated. The simulation results are found to be in approximate agreement with similarity theory. Comparisons of simulation results with certain modeling hypotheses indicate limitations in these hypotheses. The nondimensional product thickness computed from the simulations is compared with laboratory values and is found to be in reasonable agreement, especially since there are no adjustable constants in the method.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-174640 , NAS 1.26:174640 , REPT-274
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  • 93
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    Rotorcraft contingency power study (1984)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Twin helicopter engines are often sized by the power requirement of a safe mission completion after the failure of one of the two engines. This study was undertaken for NASA Lewis by General Electric Co. to evaluate the merits of special design features to provide a 2-1/2 Contingency Power rating, permitting an engine size reduction. The merits of water injection, turbine cooling airflow modulation, throttle push, and a propellant auxiliary power plant were evaluated using military Life Cycle Cost (LCC) and commercial helicopter Direct Operating Cost (DOC) merit factors in a rubber engine and a rubber aircraft scenario.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-174675 , NAS 1.26:174675 , R84AEB012
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  • 94
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    A model for reaction rates in turbulent reacting flows (1984)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: To account for the turbulent temperature and species-concentration fluctuations, a model is presented on the effects of chemical reaction rates in computer analyses of turbulent reacting flows. The model results in two parameters which multiply the terms in the reaction-rate equations. For these two parameters, graphs are presented as functions of the mean values and intensity of the turbulent fluctuations of the temperature and species concentrations. These graphs will facilitate incorporation of the model into existing computer programs which describe turbulent reacting flows. When the model was used in a two-dimensional parabolic-flow computer code to predict the behavior of an experimental, supersonic hydrogen jet burning in air, some improvement in agreement with the experimental data was obtained in the far field in the region near the jet centerline. Recommendations are included for further improvement of the model and for additional comparisons with experimental data.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-85746 , L-15679 , NAS 1.15:85746
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  • 95
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    Variable stator radial turbine (1984)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A radial turbine stage with a variable area nozzle was investigated. A high work capacity turbine design with a known high performance base was modified to accept a fixed vane stagger angle moveable sidewall nozzle. The nozzle area was varied by moving the forward and rearward sidewalls. Diffusing and accelerating rotor inlet ramps were evaluated in combinations with hub and shroud rotor exit rings. Performance of contoured sidewalls and the location of the sidewall split line with respect to the rotor inlet was compared to the baseline. Performance and rotor exit survey data are presented for 31 different geometries. Detail survey data at the nozzle exit are given in contour plot format for five configurations. A data base is provided for a variable geometry concept that is a viable alternative to the more common pivoted vane variable geometry radial turbine.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-174663 , NAS 1.26:174663 , TELEDYNE-CAE-1987
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  • 96
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    Analytical fuel property effects--small combustors (1984)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The consequences of using broad-property fuels in both conventional and advanced state-of-the-art small gas turbine combustors are assessed. Eight combustor concepts were selected for initial screening, of these, four final combustor concepts were chosen for further detailed analysis. These included the dual orifice injector baseline combustor (a current production 250-C30 engine combustor) two baseline airblast injected modifications, short and piloted prechamber combustors, and an advanced airblast injected, variable geometry air staged combustor. Final predictions employed the use of the STAC-I computer code. This quasi 2-D model includes real fuel properties, effects of injector type on atomization, detailed droplet dynamics, and multistep chemical kinetics. In general, fuel property effects on various combustor concepts can be classified as chemical or physical in nature. Predictions indicate that fuel chemistry has a significant effect on flame radiation, liner wall temperature, and smoke emission. Fuel physical properties that govern atomization quality and evaporation rates are predicted to affect ignition and lean-blowout limits, combustion efficiency, unburned hydrocarbon, and carbon monoxide emissions.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-174738 , EDR-11683 , NAS 1.26:174738 , AVSCOM-TR-84-C-14
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  • 97
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    Altitude testing of a flight weight, self-cooled, 2D thrust vectoring exhaust nozzle (1984)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The Augmented Deflector Exhaust Nozzle (ADEN) was tested in PSL-3 at NASA-Lewis Research Center using an F404 engine. The ADEN is a flight weight Single Expansion Ramp Nozzle with thrust vectoring, an internal cooling system utilizing the available engine fan flow, and a variable area throat controlled by the engine control system. Test conditions included dry and max A/B operation at nozzle pressure ratios from 2.0 to 15.0. High nozzle pressure loading was simulated to verify structural integrity at near maximum design pressure. Nozzle settings covered the full range in throat area and + or - 15 deg deflection angle. Test results demonstrated expected aerodynamic performance, cooling system effectiveness, control system stability, and mechanical integrity.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: SAE PAPER 841557
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  • 98
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    Considerations for damage analysis of gas turbine hot section components (1984)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The hot flowpath of a gas turbine engine contains static and rotating components operating in a very hostile environment. Since the reliable operation of these components is critical to the safe and efficient performance of the engine, structural life analysis of these members is carried out with great care. However, the complex nature of the strain-temperature-time cycle affecting the engine makes a general analysis procedure difficult and usually leads to separating the damage into regimes where one damage mode dominates. In particular, cycle dependent, time dependent, and thermomechanical fatigue regimes have been identified and some general considerations of each region are discussed. This discussion includes both the damage models themselves and the application of the models. Specific examples of several models are given and important factors affecting each are presented.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: ASME PAPER 84-PVP-77
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  • 99
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    Practical flight test method for determining reciprocating engine cooling requirements (1984)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: It is pointed out that efficient and effective cooling of air-cooled reciprocating aircraft engines is a continuing problem for the general aviation industry. Miley et al. (1981) have reported results of a study regarding the controlling variables for cooling and installation aerodynamics. The present investigation is concerned with experimental methods which were developed to determine cooling requirements of an instrumented prototype or production aircraft, taking into account a flight test procedure which has been refined and further verified with additional testing. It is shown that this test procedure represents a straightforward means of determining cooling requirements with minimal instrumentation. Attention is given to some background information, the development history of the NACA cooling correlation method, and the proposed modification of the NACA cooling correlation.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Journal of Aircraft (ISSN 0021-8669); 21; 936-942
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  • 100
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    Sensor failure detection for jet engines using analytical redundancy (1984)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Analytical redundant sensor failure detection, isolation and accommodation techniques for gas turbine engines are surveyed. Both the theoretical technonlogy base and demonstrated concepts are discussed. Also included is a discussion of current technology needs and angoing Government sponsored programs to meet those needs.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 84-1452
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