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  • Life and Medical Sciences  (3,185)
  • AIRCRAFT PROPULSION AND POWER  (1,219)
  • MASERS
  • 1975-1979  (3,070)
  • 1955-1959  (674)
  • 1950-1954  (661)
Collection
Keywords
Publisher
Years
Year
  • 101
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    Quiet powered-lift propulsion (1979)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Latest results of programs exploring new propulsion technology for powered-lift aircraft systems are presented. Topics discussed include results from the 'quiet clean short-haul experimental engine' program and progress reports on the 'quiet short-haul research aircraft' and 'tilt-rotor research aircraft' programs. In addition to these NASA programs, the Air Force AMST YC 14 and YC 15 programs were reviewed.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CP-2077 , E-9906 , Nov 14, 1978 - Nov 15, 1978; Cleveland, OH; United States
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    NASA TECHNICAL REPORTS
  • 102
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    Experimental studies of the formation/deposition of sodium sulfate in/from combustion gases (1979)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: An optical polarization (ellipsometric) technique was developed for measuring rapidly growing and evaporating transparent liquid condensate films (e.g., boric oxide) on solid surfaces exposed to combustion product gases. Results for the B2O3 deposition rate from BCl3-seeded propane/air flames are shown to agree well with the results of earlier interference measurements, and also with theoretical CVD predictions. Evaporation rates (from platinum ribbons into seeded propane air flames) are estimated using the polarization technique. It appears that, compared with the interference method, the polarization technique places less stringent requirements on surface quality, which may justify the added optical components needed for such measurements. It is concluded that the complementary optical methods of polarization (ellipsometry) and interference hold considerable promise for application to the rapid measurement of condensation and evaporation rates in high temperature (e.g., combustion product) environments.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-159753 , SAR-4
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    NASA TECHNICAL REPORTS
  • 103
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    JT8D and JT9D jet engine performance improvement program. Task 1: Feasibility analysis (1979)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: JT8D and JT9D component performance improvement concepts which have a high probability of incorporation into production engines were identified and ranked. An evaluation method based on airline payback period was developed for the purpose of identifying the most promising concepts. The method used available test data and analytical models along with conceptual/preliminary designs to predict the performance improvements, weight, installation characteristics, cost for new production and retrofit, maintenance cost, and qualitative characteristics of candidate concepts. These results were used to arrive at the concept payback period, which is the time required for an airline to recover the investment cost of concept implementation.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-159449 , PWA-5518-38
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    NASA TECHNICAL REPORTS
  • 104
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    The analysis of propellers including interaction effects (1979)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Analytical and experimental studies were undertaken on propellers operating in the unsteady flow field produced by interaction effects due to the fuselage, wing, and nacelles. Methods were developed and verified experimentally for determining the velocity field in which a propeller operates as well as its aerodynamic and dynamic response to this unsteady environment. Methods are presented for predicting and net thrust of a propeller-wing-body combination as well as the unsteady thrust and torque acting on the propeller. Sample calculations as well as wind tunnel and flight test results are presented which illustrate the sensitivity of a propeller to the flow field in which it is operating.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-158111 , SAE Business Aircraft Meeting; Apr 03, 1979 - Apr 06, 1979; Wichita, KS; United States
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    NASA TECHNICAL REPORTS
  • 105
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    Analysis of radiation patterns of interaction tones generated by inlet rods in the JT15D engine (1979)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Interaction tones were intentionally generated by circumferential arrays of equally spaced rods that protrude radially from the inlet wall near the face of the 28-blade fan. Arrays of 28 and 41 rods, selected to give specific far field radiation properties, were tested. The expected properties were readily apparent in the measured radiation patterns. A more detailed analysis of the test data showed both the precision and limitations of the applied acoustic theory. Rods protruding 23 percent of the radius predominantly generated only lowest radial order modes, as expected. Measured and predicted radiation patterns were generally in good agreement. The agreement, however, depended on a significant degree of implied refraction due to inlet velocity gradients. Refraction, if present, would impact static-flight noise comparisons.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-79074 , E-9891 , Aeroacoustics Conf.; Mar 12, 1978 - Mar 14, 1978; Seattle, WA; United States
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    NASA TECHNICAL REPORTS
  • 106
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    Effect of forward velocity and crosswind on the reverse-thrust performance of a variable-pitch fan engine (1979)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Variable-pitch-fan engines may be attractive for future short-haul aircraft if sufficient reverse thrust is available for aircraft deceleration after touchdown. Thrust reversal is obtained in these engines by changing fan blade pitch about 90 deg, which causes the fan airflow to enter the fan duct nozzle and exhaust through the fan inlet. This capability would eliminate the heavy and costly thrust reverser system required for current fixed-pitch turbofan engines. NASA has, therefore, supported the development of advanced technology for a quiet, clean, high-bypass-ratio turbofan engine for future short-haul aircraft. In connection with this program, tests were conducted to determine the effect of forward velocity and angle of attack on steady-state reverse-thrust performance. Other objectives of the tests were related to the determination of the effect of forward velocity on forward-to-reverse thrust transient performance and the determination of the effectiveness of an overshoot blade angle technique to establish reverse thrust during a transient. The results of the tests are discussed.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 79-0105 , American Institute of Aeronautics and Astronautics, Aerospace Sciences Meeting; Jan 15, 1979 - Jan 17, 1979; New Orleans, LA
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    NASA TECHNICAL REPORTS
  • 107
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    An analysis of thermal stress and gas bending effects on vibrations of compressor rotor stages (1979)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: A preliminary study conducted by Kerrebrock et al. (1976) has shown that the torsional rigidity of untwisted thin blades of a transonic compressor can be reduced significantly by transient thermal stresses. The aerodynamic loads have various effects on blade vibration. One effect is that gas bending loads may result in a bending-torsion coupling which may change the characteristics of the torsion and bending vibration of the blade. For a general study of transient-temperature distribution within a rotor stage, a finite-element heat-conduction analysis was developed. The blade and shroud are divided into annular elements. With a temperature distribution obtained from the heat-conduction analysis and a prescribed gas bending load distribution along the blade span, the static deformation and moment distributions of the blade can be solved iteratively using the finite-element method. The reduction of the torsional rigidity of pretwisted blades caused by the thermal stress effect is then computed. The dynamic behavior of the blade is studied by a modified Galerkin's method.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 79-0045 , American Institute of Aeronautics and Astronautics, Aerospace Sciences Meeting; Jan 15, 1979 - Jan 17, 1979; New Orleans, LA
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    NASA TECHNICAL REPORTS
  • 108
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    Alternatives for jet engine control (1979)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The research is classified in two categories: (1) the use of modern multivariable frequency domain methods for control of engine models in the neighborhood of a set-point, and (2) the use of nonlinear modelling and optimization techniques for control of engine models over a more extensive part of the flight envelope. Progress in the first category included the extension of CARDIAD (Complex Acceptability Region for Diagonal Dominance) methods developed with the help of the grant to the case of engine models with four inputs and four outputs. A suitable bounding procedure for the dominance function was determined. Progress in the second category had its principal focus on automatic nonlinear model generation. Simulations of models produced satisfactory results where compared with the NASA DYNGEN digital engine deck.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-158390
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    NASA TECHNICAL REPORTS
  • 109
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    Emission characteristics of a premix combustor fueled with a simulated partial-oxidation product gas (1979)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: A two-stage gas turbine combustor concept employing a very fuel-rich partial oxidation stage is being explored for broadening the combustion margin between ultralow emissions and the lean stability limit. Combustion and emission results are presented for a series of experiments where a simulated partial oxidation product gas was used in a premix combustor operated with inlet air state conditions typical of cruise power for high-performance aviation engines (12 atm and 850 F). Ultralow NOx, CO, and HC emissions and an extended lean burning limit were achieved simultaneously.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 79-1322 , AIAA, SAE, and ASME, Joint Propulsion Conference; Jun 18, 1979 - Jun 20, 1979; Las Vegas, NV
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    NASA TECHNICAL REPORTS
  • 110
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    A summary of NASA/Air Force Full Scale Engine Research programs using the F100 engine (1979)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: This paper summarizes a joint NASA/Air Force Full Scale Engine Research (FSER) program conducted with the F100 engine during the period 1974 through 1979. The program mechanism is described and the F100 test vehicles utilized are illustrated. Technology items which have been addressed in the areas of swirl augmentation, flutter phenomenon, advanced electronic control logic theory, strain gage technology, and distortion sensitivity are identified and the associated test programs conducted at the NASA-Lewis Research Center are described. Results presented show that the FSER approach, which utilizes existing state-of-the-art engine hardware to evaluate advanced technology concepts and problem areas, can contribute a significant data base for future system applications. Aerodynamic phenomenon previously not considered by current design systems have been identified and incorporated into current industry design tools.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 79-1308 , AIAA, SAE, and ASME, Joint Propulsion Conference; Jun 18, 1979 - Jun 20, 1979; Las Vegas, NV
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    NASA TECHNICAL REPORTS
  • 111
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    Test verification of a turbofan partial swirl afterburner (1979)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Flamespreading velocities exceeding conventional turbulent flamespreading values were demonstrated in a strong centrifugal flow field. This centrifugal flow field flamespreading concept was integrated into an F100 turbofan engine afterburner by introducing swirling airflow into the afterburner. Successful tests were conducted on F100 Engine P072 at sea level and at altitude conditions in a test chamber. This paper summarizes the design approach, engine design verification tests and performance data. Engine tests showed the swirl afterburner increased fuel-air capability improving combustion stability at adverse conditions for combustion in the engine flight envelope. No engine performance or durability degradation was observed.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 79-1199 , AIAA, SAE, and ASME, Joint Propulsion Conference; Jun 18, 1979 - Jun 20, 1979; Las Vegas, NV
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    NASA TECHNICAL REPORTS
  • 112
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    Application of digital controls on the quiet clean short haul experimental engines (1979)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The digital control systems for the Under-the-Wing (UTW) and Over-the-Wing (OTW) engines developed on the NASA/General Electric Quiet Clean Shorthaul Experimental Engine (QCSEE) program are described. The system to control engine variables includes three major functional parts: system sensors, digital control and system actuators. One of the primary control system functions is to prevent the engine from exceeding speed or temperature limits. The UTW control system also provides fault detection and condition monitoring. The control system requirements for the OTW engine are essentially the same as the UTW engine, however the inlet Mach number control requirement is eliminated, and failure indication and corrective action and full authority digital control are added. The digital controls scheduled the engine variables and maintained engine operation within all physical limits throughout the test program of approximately 200 hours of operation and provided stable and accurate control of both engines.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 79-1203 , AIAA, SAE, and ASME, Joint Propulsion Conference; Jun 18, 1979 - Jun 20, 1979; Las Vegas, NV
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    NASA TECHNICAL REPORTS
  • 113
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    Effect of shocks on film cooling of a full scale turbojet exhaust nozzle having an external expansion surface (1979)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Cooling is one of the critical technologies for efficient design of exhaust nozzles, especially for the developing technology of nonaxisymmetric (2D) nozzles for future aircraft applications. Several promising 2D nozzle designs have external expansion surfaces which need to be cooled. Engine data are scarce, however, on nozzle cooling effectiveness in the supersonic flow environment (with shocks) that exists along external expansion surfaces. This paper will present experimental film cooling data obtained during exploratory testing with an axisymmetric plug nozzle having external expansion and installed on an afterburning turbojet engine in an altitude test facility. The data obtained shows that the shocks and local hot gas stream conditions have a marked effect on film cooling effectiveness. An existing film cooling correlation is adequate at some operating conditions but inadequate at other conditions such as in separated flow regions resulting from shock-boundary-layer interactions.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 79-1170 , AIAA, SAE, and ASME, Joint Propulsion Conference; Jun 18, 1979 - Jun 20, 1979; Las Vegas, NV
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    NASA TECHNICAL REPORTS
  • 114
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    General aviation turbine engine /GATE/ concepts (1979)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The paper deals with only a portion of the work done by Williams Research Corporation for NASA. It provides a look at possible new-generation powerplants that offer the potential for remarkable airplane performance gains with attendant safety, utility, productivity and life cycle cost benefits. Attention is given to a turboprop engine concept and applications. A turbofan engine having core components in common with the turboprop is also discussed and an airplane application shown. Some of the more important findings are presented.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 79-1157 , AIAA, SAE, and ASME, Joint Propulsion Conference; Jun 18, 1979 - Jun 20, 1979; Las Vegas, NV
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    NASA TECHNICAL REPORTS
  • 115
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    Multivariable control altitude demonstration on the F100 turbofan engine (1979)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The F100 Multivariable control synthesis (MVCS) program, was aimed at demonstrating the benefits of LGR synthesis theory in the design of a multivariable engine control system for operation throughout the flight envelope. The advantages of such procedures include: (1) enhanced performance from cross-coupled controls, (2) maximum use of engine variable geometry, and (3) a systematic design procedure that can be applied efficiently to new engine systems. The control system designed, under the MVCS program, for the Pratt & Whitney F100 turbofan engine is described. Basic components of the control include: (1) a reference value generator for deriving a desired equilibrium state and an approximate control vector, (2) a transition model to produce compatible reference point trajectories during gross transients, (3) gain schedules for producing feedback terms appropriate to the flight condition, and (4) integral switching logic to produce acceptable steady-state performance without engine operating limit exceedance.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-79183 , E-050 , Joint Propulsion Conf.; Jun 18, 1979 - Jun 20, 1979; Las Vegas, NV; United States
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    NASA TECHNICAL REPORTS
  • 116
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    Full-scale wind tunnel study of nacelle shape on cooling drag (1979)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Tests were made in the NASA-Ames 40- by 80 Foot Wind Tunnel of a wing semispan with a nacelle (no propeller) from a typical, general aviation twin-engine aircraft. Measurements were made of the effect on drag of the cooling air flow through the nacelle. Internal and external nacelle pressures were measured. It was found that the cooling flow accounts for about 13% of the estimated airplane drag and about 42% of the cooling flow drag is associated with the internal flow. It was concluded that improvements could be made by relocating both the inlet and the outlet of the cooling air.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 79-1820 , American Institute of Aeronautics and Astronautics, Aircraft Systems and Technology Meeting; Aug 20, 1979 - Aug 22, 1979; New York, NY
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    NASA TECHNICAL REPORTS
  • 117
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    Numerical investigation of the perpendicular injector flow field in a hydrogen fueled scramjet (1979)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: A computer program has been developed which numerically solves the full (elliptic) two-dimensional Navier-Stokes and specie equations near a slotted perpendicular hydrogen fuel injector in a scramjet engine. The program currently predicts the turbulent mixing of injected hydrogen fuel and air without reaction, and allows the study of separated regions of flow immediately preceding and following the injector as well as the complex shock-expansion structure produced by the injector in this region of the engine. Results are presented that describe the size of the separated regions near the injector as well as locations where ignition is likely to occur.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 79-1482 , American Institute of Aeronautics and Astronautics, Fluid and Plasma Dynamics Conference; Jul 23, 1979 - Jul 25, 1979; Williamsburg, VA
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    NASA TECHNICAL REPORTS
  • 118
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    Lean stability augmentation for premixing, prevaporizing combustors (1979)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: An experimental program was conducted to investigate techniques for improving the lean combustion limits of premixing, prevaporizing combustors applicable to gas turbine engine main burners. Augmented flameholders employing recessed perforated plates, catalyzed tube bundles, and configurations in which pilot fuel was injected into the wakes of V-gutters or perforated plates were designed and tested. Stable operation of the piloted designs was achieved at equivalence ratios as low as 0.25; NOx emissions of less than 1.0 g/kg at simulated turbine engine cruise conditions were obtained. A piloted perforated plate employing four percent pilot fuel flow produced the best performance while meeting severe NOx constraints.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 79-1319 , AIAA, SAE, and ASME, Joint Propulsion Conference; Jun 18, 1979 - Jun 20, 1979; Las Vegas, NV
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    NASA TECHNICAL REPORTS
  • 119
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    LDV measurements on propellers (1979)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Laser Doppler velocimeter (LDV) measurements of the flow velocity around high-efficiency propeller blades for high disk loading turboprop propulsion systems are reported. The wind-tunnel flow around sets of eight straight and swept propeller blades with the same twist and chord distributions was measured using a conventional two-color dual scatter LDV system. The measurements of the axial flow velocities a small distance in front of the propeller blade, between the blade row, and downstream of the propeller are shown to provide information necessary for the determination of overall performance, swirl angle distribution, blade loading distributions, local lift and drag coefficients, interference effects, shock location, local induced velocities, wake characteristics and stall pattern.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Laser velocimetry and particle sizing; Third International Workshop; Jul 11, 1978 - Jul 13, 1978; West Lafayette, IN
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    NASA TECHNICAL REPORTS
  • 120
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    The selection of materials technologies for full-scale development (1979)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: Candidate material technologies offering the largest application payoff for the least development costs and the least risk should be selected for full-scale development funding. A cost/benefit methodology is developed to rate candidate material and process opportunities for future aircraft engine applications. A development cost estimate and risk analysis is compared with the economic benefit to establish a ranking of the candidate advanced technologies. Also included are examples of this methodology as applied to high-strength HIP turbine disks, advanced oxide dispersion strengthened burner liners, and ceramic first-stage high-pressure turbine vanes.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 79-1152 , AIAA, SAE, and ASME, Joint Propulsion Conference; Jun 18, 1979 - Jun 20, 1979; Las Vegas, NV
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    NASA TECHNICAL REPORTS
  • 121
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    Design and performance of the propulsion system for the quiet short-haul research aircraft /QSRA/ (1979)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: This paper describes the design and performance of the Quiet Short-Haul Research Aircraft (QSRA) propulsion system. A discussion of the mixed-flow boundary layer control (BLC) system, which uses high and low pressure engine bleed air, is included. This system seriously affected propulsion system performance, particularly engine acceleration characteristics, requiring an integration of BLC system and powerplant controls. Funding limitations for the QSRA Project prevented extensive full-scale testing and systems mockups, resulting in a high reliance on small-scale tests and analytical techniques. Ground tests of the actual aircraft systems showed that the extrapolation of small-scale tests and analytical techniques were in good agreement with measured full-scale results.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 79-1313 , AIAA, SAE, and ASME, Joint Propulsion Conference; Jun 18, 1979 - Jun 20, 1979; Las Vegas, NV
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    NASA TECHNICAL REPORTS
  • 122
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    Causes of high pressure compressor deterioration in service (1979)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The high mechanical reliability and low deterioration rate of the JT9D high-pressure compressor results in long utilization without exceeding engine operational limits. The increasing cost and decreasing supply of fuel have focused attention on the fuel burned implications of such high time use without refurbishment. The paper presents the results of JT9D high pressure compressor studies. The mechanical deterioration of the JT9D high-pressure compressor gaspath parts versus increasing service usage, documented from inspection of service parts, is presented and discussed including changes in airfoil roughness, blade length, airfoil contour and outer air seal trench characteristics. An estimate of the performance loss versus usage is related to each type of damage. The combined estimated high-pressure compressor performance loss for all mechanisms determined from part inspection is compared to historical engine test data to establish the validity of the predicted loss levels. The effect of cold section refurbishment on engine fuel consumption recovery and the results of an optimization study to determine the appropriate interval for high pressure compressor refurbishment are also reported.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 79-1234 , AIAA, SAE, and ASME, Joint Propulsion Conference; Jun 18, 1979 - Jun 20, 1979; Las Vegas, NV
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    NASA TECHNICAL REPORTS
  • 123
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    Autoignition of hydrogen injected transverse to a supersonic airstream (1979)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: A parametric study of autoignition characteristics of transverse fuel injector patterns for a hydrogen-fueled, supersonic-combustion ramjet was conducted in direct-connect tests over a range of simulated hypersonic flight conditions. Autoignition limits, defined directly by visual observations and indirectly by measured wall pressure and temperature, are compared with a semi-empirical ignition limit model which accounts for first order effects on autoignition. It is shown that to initiate combustion in the immediate region of the fuel injector, ignition must occur in the separation region ahead of the fuel jet. Autoignition within this separation zone exhibits strong dependence on flow pressure and temperature, injector diameter, local boundary layer energy thickness, wall temperature, and on fluid dynamic interactions with adjacent downstream facing steps (such as inlet isolation steps). Secondary effects are also discussed. The empirical model is used to define limits of test temperature, pressure, and scale required for autoignition in a current subscale engine test program.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 79-1239 , AIAA, SAE, and ASME, Joint Propulsion Conference; Jun 18, 1979 - Jun 20, 1979; Las Vegas, NV
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    NASA TECHNICAL REPORTS
  • 124
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    Materials and structural aspects of advanced gas-turbine helicopter engines (1979)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Advances in materials, coatings, turbine cooling technology, structural and design concepts, and component-life prediction of helicopter gas-turbine-engine components are presented. Stationary parts including the inlet particle separator, the front frame, rotor tip seals, vanes and combustors and rotating components - compressor blades, disks, and turbine blades - are discussed. Advanced composite materials are considered for the front frame and compressor blades, prealloyed powder superalloys will increase strength and reduce costs of disks, the oxide dispersion strengthened alloys will have 100C higher use temperature in combustors and vanes than conventional superalloys, ceramics will provide the highest use temperature of 1400C for stator vanes and 1370C for turbine blades, and directionally solidified eutectics will afford up to 50C temperature advantage at turbine blade operating conditions. Coatings for surface protection at higher surface temperatures and design trends in turbine cooling technology are discussed. New analytical methods of life prediction such as strain gage partitioning for high temperature prediction, fatigue life, computerized prediction of oxidation resistance, and advanced techniques for estimating coating life are described.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Association Aeronautique et Astronautique de France, International Congress in Aeronautics; Jun 06, 1979 - Jun 08, 1979; Paris; France
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    NASA TECHNICAL REPORTS
  • 125
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    Evaluation of two inflow control devices for flight simulation of fan noise using a JT15D engine (1979)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The program was developed to accurately simulate flight fan noise on ground static test stands. The results generally indicated that both the induct and external ICD's were effective in reducing the inflow turbulence and the fan blade passing frequency tone generated by the turbulence. The external ICD was essentially transparent to the propagating fan tone but the induct ICD caused attenuation under most conditions.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-79072 , E-9889 , Aeroacoustics Conf.; Mar 12, 1978 - Mar 14, 1978; Seattle, WA; United States
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    NASA TECHNICAL REPORTS
  • 126
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    The gate studies: Assessing the potential of future small general aviation turbine engines (1979)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Four studies were completed that explore the opportunities for future General Aviation turbine engines (GATE) in the 150-1000 SHP class. These studies forecasted the potential impact of advanced technology turbine engines in the post-1988 market, identified important aircraft and missions, desirable engine sizes, engine performance, and cost goals. Parametric evaluations of various engine cycles, configurations, design features, and advanced technology elements defined baseline conceptual engines for each of the important missions identified by the market analysis. Both fixed-wing and helicopter aircraft, and turboshaft, turboprop, and turbofan engines were considered. Sizable performance gains (e.g., 20% SFC decrease), and large engine cost reductions of sufficient magnitude to challenge the reciprocating engine in the 300-500 SHP class were predicted.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-79075 , E-9892 , Intern. Ann. Gas Turbine Conf.; Mar 11, 1979 - Mar 15, 1979; San Diego, CA; United States
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    Measured and predicted noise of the Avco-Lycoming YF-102 turbofan noise (1979)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Acoustic testing of the AVCO-Lycoming YF-102 turbofan engine was done on a static test stand in support of the quiet short-haul research aircraft acoustic design. Overall noise levels were dominated by the fan noise emanating from the exhaust duct, except at high power settings when combination tones were generated in the fan inlet. Component noise levels, calculated by noise prediction methods were in reasonable agreement with the measured results. Far-field microphones placed at ground level were found superior to those at engine centerline height, even at high frequencies.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-79069 , E-9885 , AIAA PAPER 79-0641 , Aeroacoustics Conf.; Mar 12, 1979 - Mar 14, 1979; Seattle, WA; United States
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  • 128
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    Preliminary QCGAT program test results (1979)
    In:  CASI
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    Publication Date: 2019-07-13
    Description: NASA Lewis Research Center is conducting a program to demonstrate that large commercial engine technology can be applied to general aviation engines to reduce noise, emissions and fuel consumption and to develop new technology where required. The overall engine program, design, and technology incorporated into the QCGAT engines are described. In addition, preliminary engine test results are presented and compared to the technical requirements the engines were designed to meet.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-79013 , E-9802 , Business Aircraft Meeting; Apr 03, 1979 - Apr 06, 1979; Wichita, KS; United States
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    The advanced low-emissions catalytic-combuster program. Phase 1: Description and status (1979)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: An overview of the ongoing program is presented. Objectives, plan, schedule, pollution and performance goals, catalyst advantages, present problems, and the present status of identified combustor concepts are discussed. The possible increase in upper atmosphere oxides of nitrogen (NOx) levels due to aircraft number density increases was predicted to adversely decrease ozone concentration levels. A technique for achieving low NOx emission levels was experimentally demonstrated with a lean, premixing prevaporizing flame-tube combustor.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-79049 , E-9853 , Ann. Intern. Gas Turbine Conf. and 1st Solar Energy Conf.; Mar 11, 1979 - Mar 15, 1979; San Diego, CA; United States
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  • 130
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    Identification of a STOL propulsion plant model from flight data (1979)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: Accurate dynamic models for propulsion system behavior are critical to successful synthesis of STOL autothrottle/autoland control systems. This paper describes the development of a nonlinear dynamic model for the response of a STOL aircraft in the landing/approach configuration. The model is based upon an analysis of the throttle, governor, and turbofan engine components. Model parameters are directly identified from data acquired during a flight of the NASA Augmentor Wing Jet STOL research aircraft. The accuracy of the model and a comparison of results for two engines are described. Various approaches to modeling propulsion system response for complex systems representative of current and near-term aircraft are discussed.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Journal of Guidance and Control; 2; May-June
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  • 131
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    Influence of coolant tube curvature on film cooling effectiveness as detected by infrared imagery (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Thermal film cooling footprints observed by infrared imagery from straight, curved, and looped coolant tube geometries are compared. It was hypothesized that the differences in secondary flow and in the turbulence structure of flow through these three tubes should influence the mixing properties between the coolant and the main stream. A flow visualization tunnel, an infrared camera and detector, and a Hilsch tube were employed to test the hypothesis.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TP-1546 , E-066
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  • 132
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    VSCE technology definition study (1979)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: Refined design definition of the variable stream control engine (VSCE) concept for advanced supersonic transports is presented. Operating and performance features of the VSCE are discussed, including the engine components, thrust specific fuel consumption, weight, noise, and emission system. A preliminary engine design is presented.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-159730 , PWA-5630-11
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  • 133
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    Ceramic regenerator systems development program (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-159541 , DOE/NASA/0008-79/6
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  • 134
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    Effects of diffusion factor, aspect ratio and solidity on overall performance of 14 compressor middle stages (1979)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: A series of high hub tip radius ratio compressor stages representative of the middle and latter stages of axial flow compressors is discussed. The effects of aspect ratio, diffusion factor, and solidity on rotor and stage performance are determined. Fourteen middle stages are tested to study the effects on performance of varying both diffusion through the rotor and stator blades and blade aspect ratio. The design parameters in the streamline analysis program, the blade geometry program, and the blade coordinate program are presented.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TP-1523 , E-9943
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  • 135
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    CF6 jet engine performance improvement program. Short core exhaust nozzle performance improvement concept (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The short core exhaust nozzle was evaluated in CF6-50 engine ground tests including performance, acoustic, and endurance tests. The test results verified the performance predictions from scale model tests. The short core exhaust nozzle provides an internal cruise sfc reduction of 0.9 percent without an increase in engine noise. The nozzle hardware successfully completed 1000 flight cycles of endurance testing without any signs of distress.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-159564
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  • 136
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    Analytical evaluation of the impact of broad specification fuels on high bypass turbofan engine combustors (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Six conceptual combustor designs for the CF6-50 high bypass turbofan engine and six conceptual combustor designs for the NASA/GE E3 high bypass turbofan engine were analyzed to provide an assessment of the major problems anticipated in using broad specification fuels in these aircraft engine combustion systems. Each of the conceptual combustor designs, which are representative of both state-of-the-art and advanced state-of-the-art combustion systems, was analyzed to estimate combustor performance, durability, and pollutant emissions when using commercial Jet A aviation fuel and when using experimental referee board specification fuel. Results indicate that lean burning, low emissions double annular combustor concepts can accommodate a wide range of fuel properties without a serious deterioration of performance or durability. However, rich burning, single annular concepts would be less tolerant to a relaxation of fuel properties. As the fuel specifications are relaxed, autoignition delay time becomes much smaller which presents a serious design and development problem for premixing-prevaporizing combustion system concepts.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-159641 , R79AEG504
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  • 137
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    Standalone engine simulator (SAES), Engine Dynamics simulator (EDS) Xerox Sigma 5 interface hardware manual (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The ESS-EDS and EDS-Sigma interfaces within the standalone engine simulator are described. The operation of these interfaces, including the definition and use of special function signals and data flow paths within them during data transfers, is presented along with detailed schematics and circuit layouts of the described equipment.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-161301 , REPT-78-113
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  • 138
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    Flow in nonrotating passages of radial inflow turbines (1979)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: The analysis of irrotational incompressible flow field in the stator unit of a radial inflow turbine is presented. The solution in the combined scroll-nozzle assembly is complicated by the domain geometry and by its multiconnectivity. This model is necessary, however, in order to provide a better understanding of the mutual interaction effects of these two components on the flow field. The finite element method is used in the solution which is limited to the two dimensional case. A substructuring technique is adopted in the computational procedure and results in considerable savings in both computer time and core storage requirements. The results are presented for the flow velocity magnitude and direction in the scroll and through the various nozzles, for two nozzle blade geometries. In addition, the mass flow rates in the different nozzles are computed and their deviations from the mean value determined.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-159679
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  • 139
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    Acoustic analysis of the propfan (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A review of propeller noise prediction technology is presented. Two methods for the prediction of the noise from conventional and advanced propellers in forward flight are described. These methods are based on different time domain formulations. Brief descriptions of the computer algorithms based on these formulations are given. The output of the programs (the acoustic pressure signature) was Fourier analyzed to get the acoustic pressure spectrum. The main difference between the two programs is that one can handle propellers with supersonic tip speed while the other is for subsonic tip speed propellers. Comparisons of the calculated and measured acoustic data for a conventional and an advanced propeller show good agreement in general.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-162312
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  • 140
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    Lean, premixed, prevaporized fuel combustor conceptual design study (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Four combustor concepts, designed for the energy efficient engine, utilize variable geometry or other flow modulation techniques to control the equivalence ratio of the initial burning zone. Lean conditions are maintained at high power to control oxides of nitrogen while near stoichometric conditions are maintained at low power for low CO and THC emissions. Each concept was analyzed and ranked for its potential in meeting the goals of the program. Although the primary goal of the program is a low level of nitric oxide emissions at stratospheric cruise conditions, both the ground level EPA emission standards and combustor performance and operational requirements typical of advanced subsonic aircraft engines are retained as goals as well. Based on the analytical projections made, two of the concepts offer the potential of achieving the emission goals; however, the projected operational characteristics and reliability of any concept to perform satisfactorily over an entire aircraft flight envelope would require extensive experimental substantiation before engine adaptation can be considered.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-159647 , PWA-5626-12
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  • 141
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    Conceptual study of a turbojet/ramjet inlet (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: An inlet concept for separate turbojet and ramjet engines was defined and compared with an equivalent inlet for a wraparound turboramjet engine. The comparison was made for a typical high altitude hypersonic cruise vehicle where the turbojet inlet capture area was required to be half as large as the ramjet inlet capture area at cruise. The use of a shorter nacelle having substantially lower cooling requirements at cruise for the inlet concept for separate turbojet and ramjet engines is suggested. The separate engine concept better isolates the turbojet from the ramjet, requires no special close off mechanisms within the turbojet, and avoids the circumferential heat load imposed by a wraparound ramjet. A more variable geometry is required.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-80141 , L-13036
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  • 142
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    Aerodynamic performance of axial-flow fan stage operated at nine inlet guide vane angles (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The overall performance of a fan stage with nine inlet guide vane angle settings is presented. These data were obtained over the stable flow range at speeds from 60 to 120 percent of design for vane setting angles from -25 to 42.5 degrees. At design speed and design inlet guide vane angle, the stage has a peak efficiency of 0.892 at a pressure ratio of 1.322 and a flow of 25.31 kg/s. The stall margin based on peak efficiency and stall was 20 percent. Based on an operating line passing through the peak efficiency point at the design setting angle, the useful operating range of the stage at design speed is limited by stall at the positive setting angles and by choke at the negative angles. At design the calculated static thrust along the operating line varied from 68 to 114 percent of that obtained at design setting angle.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TP-1510 , E-9714
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  • 143
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    Aerodynamic performance of 1.38-pressure-ratio, variable-pitch fan stage (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The performance of a variable pitch fan stage tested over a range of blade setting angles, speeds, and flows is presented. The fan was designed for a tip speed of 289.6 m/sec and a flow of 29.6 kg/sec. The measured performance agreed reasonably well with the design point. The stall margin was only 5 percent. Static thrust values along an operating line ranged from less than 15 to over 115 percent of that at design angle as the blade setting angle was varied from 25 degrees (closed) to -8 degrees (opened). The use of casing treatment increased the stall margin to 20.6 percent but decreased efficiency by 4 percentage points.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TP-1502 , E-9700
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  • 144
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    JT9D-70/59 Improved High Pressure Turbine Active Clearance Control System (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The JT9D-70/59 high pressure turbine active clearance control system was modified to provide reduction of blade tip clearance when the system is activated during cruise operation. The modification increased the flow capacity and air impingement effectiveness of the cooling air manifold to augment turbine case shrinkage capability, and increased responsiveness of the airseal clearance to case shrinkage. The simulated altitude engine testing indicated a significant improvement in specific fuel consumption with the modified system. A 1000 cycle engine endurance test showed no unusual wear or performance deterioration effects on the engine or the clearance control system. Rig tests indicated that the air impingement and seal support configurations used in the engine tests are near optimum.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-159661 , PWA-5515-87C
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  • 145
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    Aerodynamic and acoustic investigation of inverted velocity profile coannular exhaust nozzle models and development of aerodynamic and acoustic prediction procedures (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Five co-annular nozzle models, covering a systematic variation of nozzle geometry, were tested statically over a range of exhaust conditions including inverted velocity profile (IVP) (fan to primary stream velocity ratio 1) and non IVP profiles. Fan nozzle pressure ratio (FNPR) was varied from 1.3 to 4.1 at primary nozzle pressure ratios (PNPR) of 1.53 and 2.0. Fan stream temperatures of 700 K (1260 deg R) and 1089 K(1960 deg R) were tested with primary stream temperatures of 700 K (1260 deg R), 811 K (1460 deg R), and 1089 K (1960 deg R). At fan and primary stream velocities of 610 and 427 m/sec (2000 and 1400 ft/sec), respectively, increasing fan radius ratio from 0.69 to 0.83 reduced peak perceived noise level (PNL) 3 dB, and an increase in primary radius ratio from 0 to 0.81 (fan radius ratio constant at 0.83) reduced peak PNL an additional 1.0 dB. There were no noise reductions at a fan stream velocity of 853 m/sec (2800 ft/sec). Increasing fan radius ratio from 0.69 to 0.83 reduced nozzle thrust coefficient 1.2 to 1.5% at a PNPR of 1.53, and 1.7 to 2.0% at a PNPR of 2.0. The developed acoustic prediction procedure collapsed the existing data with standard deviation varying from + or - 8 dB to + or - 7 dB. The aerodynamic performance prediction procedure collapsed thrust coefficient measurements to within + or - .004 at a FNPR of 4.0 and a PNPR of 2.0.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-3168 , PWA-5550-8
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    Experimental Clean Combustor Program (ECCP), phase 3 (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A double annular advanced technology combustor with low pollutant emission levels was evaluated in a series of CF6-50 engine tests. Engine lightoff was readily obtained and no difficulties were encountered with combustor staging. Engine acceleration and deceleration were smooth, responsive and essentially the same as those obtainable with the CF6-50 combustor. The emission reductions obtained in carbon monoxide, hydrocarbons, and nitrogen oxide levels were 55, 95, and 30 percent, respectively, at an idle power setting of 3.3 percent of takeoff power on an EPA parameter basis. Acceptable smoke levels were also obtained. The exit temperature distribution of the combustor was found to be its major performance deficiency. In all other important combustion system performance aspects, the combustor was found to be generally satisfactory.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-135384 , R79AEG410
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  • 147
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    Criteria for self-ignition of supersonic hydrogen-air mixtures (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A correlation of available self ignition data for supersonic hydrogen-air mixtures in configurations representative of scramjet combustors was made. The correlation was examined in light of simplified ignition-limit models. The data and model included cases of injection from transverse fuel jets on walls, transverse jets behind swept and unswept steps, and transverse injection ahead of swept and unswept steps and strut bases. The results provide useful guidance for predicting self ignition in a variety of applications. The likely regions for self ignition in a combustor are given in order of merit.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TP-1457 , L-12678
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  • 148
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    NASA CF6 jet engine diagnostics program: Long-term CF6-6D low-pressure turbine deterioration (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Back-to-back performance tests were run on seven airline low pressure turbine (LPT) modules and four new CF6-6D modules. Back-to-back test cell runs, in which an airline LPT module was directly compared to a new production module, were included. The resulting change, measured in fuel burn, equaled the level of LPT module deterioration. Three of the LPT modules were analytically inspected followed by a back-to-back test cell run to evaluate current refurbishment techniques.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-159618 , R79AEG356
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  • 149
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    Engine Rotor Burst Containment/Control Studies (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Investigations on the impact-interaction of both complex engine rotor fragments and simple fragments with various types of single-layer and multilayer containment structures were reviewed. The resulting data were used (1) to develop empirical design rules and (2) to evaluate proposed theoretical methods for predicting the impact induced responses of containment structures. Examples of typical numerical methods for predicting the large deflection, elastic-plastic transient structural responses of simple two dimensional and three dimensional containment shields were illustrated.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AGARD Stresses, Vibrations, Struct. Integration and Eng. Integrity (Including Aeroelasticity and Flutter); 30 p
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  • 150
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    Evaluation of a simplified gross thrust calculation technique using two prototype F100 turbofan engines in an altitude facility (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The technique which relies on afterburner duct pressure measurements and empirical corrections to an ideal one dimensional flow analysis to determine thrust is presented. A comparison of the calculated and facility measured thrust values is reported. The simplified model with the engine manufacturer's gas generator model are compared. The evaluation was conducted over a range of Mach numbers from 0.80 to 2.00 and at altitudes from 4020 meters to 15,240 meters. The effects of variations in inlet total temperature from standard day conditions were explored. Engine conditions were varied from those normally scheduled for flight. The technique was found to be accurate to a twice standard deviation of 2.89 percent, with accuracy a strong function of afterburner duct pressure difference.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TP-1482 , H-1061
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  • 151
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    Rotor redesign for a highly loaded 1800 ft/sec tip speed fan. 1: Aerodynamic and mechanical design report (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A quasi three dimensional design system and multiple-circular-arc airfoil sections were used to design a fan rotor. An axisymmetric intrablade flow field calculation modeled the shroud of an isolated splitter and radial distribution. The structural analysis indicates that the design is satisfactory for evaluation of aerodynamic performance of the fan stage in a test facility.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-159596 , PWA-5523-42
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  • 152
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    Thrust and mass flow characteristics of four 36 inch diameter tip turbine fan thrust vectoring systems in and out of ground effect (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The calibration tests carried out on the propulsion system components of a 70 percent scale, powered model of a NASA 3-fan V/STOL aircraft configuration are described. The three X3/6B/T58 turbotip fan units used in the large scale powered model were tested on an isolated basis over a range of ground heights from H/D of 1.02 to infinity. A higher pressure ratio LF336/J85 fan unit was tested over a range of ground heights from 1.55 to infinity. The results of the test program demonstrated that: (1) the thrust and mass flow performance of the X376B/T58 nose lift unit is essentially constant for H/D variations down to 1.55; at H/D 1.02 back pressurization of the fan exit occurs and is accompanied by an increase in thrust of five percent; (2) a change in nose fan exit hub shape from flat plate to hemispherical produces no significant difference in louvered lift nozzle performance for height variations from H/D = 1.02 to infinity; (3) operation of the nose lift nozzle at the higher fan pressure ratio generated by the LF336/J85 fan system causes no significant change in ground proximity performance down to an H/D of 1.55, the lowest height tested with this unit; and (4) the performance of the left and right X376B/T58 lift/cruise units in the vertical lift mode remains unchanged, within plus or minus two percent for the range of ground heights from H/D = 1.02 to infinity.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-152239 , MDC-A5704
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    Interference effects of aircraft components on the local blade angle of attack of a wing-mounted propeller (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The aerodynamic interference effects on a propeller operating in the presence of different wing-body-nacelle combinations was studied. The unsteady blade angle of attack variation with azimuth angle by varying the pitch and yaw of the nacelle was minimized. Results indicate for the particular configuration of interest the minimum blade angle of attack variation occurred with the nacelle pitched downward 4.5 deg and yawed inward 3.0 deg.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-78587 , A-7812
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  • 154
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    Operating condition and geometry effects on low-frequency afterburner combustion instability in a turbofan at altitude (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Three afterburner configurations were tested in a low-bypass-ratio turbofan engine to determine the effect of various fuel distributions, inlet conditions, flameholder geometry, and fuel injection location on combustion instability. Tests were conducted at simulated flight conditions of Mach 0.75 and 1.3 at altitudes from 11,580 to 14,020 m (38,000 to 46,000 ft). In these tests combustion instability with frequency from 28 to 90 Hz and peak-to-peak pressure amplitude up to 46.5 percent of the afterburner inlet total pressure level was encountered. Combustion instability was suppressed in these tests by varying the fuel distribution in the afterburner.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TP-1475 , E-9886
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  • 155
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    Design study and performance analysis of a high-speed multistage variable-geometry fan for a variable cycle engine (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A design technology study was performed to identify a high speed, multistage, variable geometry fan configuration capable of achieving wide flow modulation with near optimum efficiency at the important operating condition. A parametric screening study of the front and rear block fans was conducted in which the influence of major fan design features on weight and efficiency was determined. Key design parameters were varied systematically to determine the fan configuration most suited for a double bypass, variable cycle engine. Two and three stage fans were considered for the front block. A single stage, core driven fan was studied for the rear block. Variable geometry concepts were evaluated to provide near optimum off design performance. A detailed aerodynamic design and a preliminary mechanical design were carried out for the selected fan configuration. Performance predictions were made for the front and rear block fans.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-159545
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  • 156
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    Time optimal control of a jet engine using a quasi-Hermite interpolation model (1979)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: This work made preliminary efforts to generate nonlinear numerical models of a two-spooled turbofan jet engine, and subject these models to a known method of generating global, nonlinear, time optimal control laws. The models were derived numerically, directly from empirical data, as a first step in developing an automatic modelling procedure.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-158711 , EE-791
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  • 157
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    Advanced General Aviation Turbine Engine (GATE) concepts (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Concepts are discussed that project turbine engine cost savings through use of geometrically constrained components designed for low rotational speeds and low stress to permit manufacturing economies. Aerodynamic development of geometrically constrained components is recommended to maximize component efficiency. Conceptual engines, airplane applications, airplane performance, engine cost, and engine-related life cycle costs are presented. The powerplants proposed offer encouragement with respect to fuel efficiency and life cycle costs, and make possible remarkable airplane performance gains.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-159603 , WRC-78-113-15
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  • 158
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    Modelling turbulent flame ignition and blowout (1979)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: A statistical mixing model incorporating an overall rate equation to describe the fuel oxidation process was developed for studies of ignition and blowout in a combustor primary zone. This zone is treated as a partially stirred reactor whose composition is described by a statistical ensemble of equal mass fluid elements. This ensemble experiences mixing interactions, which represent the turbulent mixing process, at time intervals governed by an empirically determined mixing frequency. Each mixing interaction is computed by ramdomly selecting two different elements which are then allowed to mix completely so that they reach a mean composition depending on their thermodynamic states prior to mixing. The two elements then separate, and the chemical kinetics proceed depending on their new composition and temperature.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Lewis Res. Center Premixed Prevaporized Combustor Technol. Forum; p 179-186
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  • 159
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    Effect of fuel sprays on emissions (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A research gas turbine combustor was operated under realistic conditions such that the influence of individual variables (in particular, fuel spray characteristics) on emissions could be determined. The special combustor allows independent control over drop size, fuel-air ratio, air inlet temperature, pressure, reference velocity, and residence time. Also, it lends itself to theoretical modeling and turbulent intensity measurements through use of laser velocimetry. Emission results for a range of operations are presented. A number of graphs show which show the variations of emissions levels with one variable at a time are included. In every case, the fuel is jet A, the pressure is atmospheric, and combustion is limited to a primary zone.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Lewis Res. Center Premixed Prevaporized Combustor Technol. Forum; p 67-84
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  • 160
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    Theory of low frequency noise transmission through turbines (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Improvements of the existing theory of low frequency noise transmission through turbines and development of a working prediction tool are described. The existing actuator-disk model and a new finite-chord model were utilized in an analytical study. The interactive effect of adjacent blade rows, higher order spinning modes, blade-passage shocks, and duct area variations were considered separately. The improved theory was validated using the data acquired in an earlier NASA program. Computer programs incorporating the improved theory were produced for transmission loss prediction purposes. The programs were exercised parametrically and charts constructed to define approximately the low frequency noise transfer through turbines. The loss through the exhaust nozzle and flow(s) was also considered.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-159457 , R77AEG570
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  • 161
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    Parametric performance of a turbojet engine combustor using jet A and A diesel fuel (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The performance of a single-can JT8D combustor was evaluated with Jet A and a high-aromatic diesel fuel over a parametric range of combustor-inlet conditions. Performance parameters investigated were combustion efficiency, emissions of CO, unburned hydrocarbons, and NOx, as well as liner temperatures and smoke. At all conditions the use of diesel fuel instead of Jet A resulted in increases in smoke numbers and liner temperatures; gaseous emissions, on the other hand, did not differ significantly between the two fuels.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-79089 , E-9913
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  • 162
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    Advanced General Aviation Turbine Engine (GATE) study (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The small engine technology requirements suitable for general aviation service in the 1987 to 1988 time frame were defined. The market analysis showed potential United States engines sales of 31,500 per year providing that the turbine engine sales price approaches current reciprocating engine prices. An optimum engine design was prepared for four categories of fixed wing aircraft and for rotary wing applications. A common core approach was derived from the optimum engines that maximizes engine commonality over the power spectrum with a projected price competitive with reciprocating piston engines. The advanced technology features reduced engine cost, approximately 50 percent compared with current technology.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-159624 , TELEDYNE-CAE-1600
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  • 163
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    Effect of rotor meridional velocity ratio on response to inlet radial and circumferential distortion (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Three single transonic fan stages, each having a different meridional velocity ratio across its rotor, were tested with two magnitudes of tip radial distortion and with a 90 deg circumferential distortion imposed on the inlet flow. The rotor with the lowest meridional velocity ratio (less than 0.9 at the tip) demonstrated the least degradation of performance due to these distortions. Loss and deviation angle data (as needed for performance prediction with radial distortion) calculated along actual streamlines for radially distorted flow and correlated against diffusion factor, showed consistent agreement with data calculated along design streamlines for undistorted flow.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TP-1278 , E-8987
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  • 164
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    Effect of steady-state pressure distortion on flow characteristics entering a turbofan engine (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Flow angle, static-pressure, and total-pressure distributions were measured in the passage ahead of a turbofan engine operating with inlet pressure distortion. Distortions were generated with five screen configurations and one solid plate configuration. The screens and solid plate were circumferential and mounted on a rotatable assembly. Reynolds Number Index upstream of the distortion device was maintained at 0.5, 0.35, or 0.2, and engine corrected low-rotor speeds were held at 6000 rpm and 8600 rpm. Near the engine inlet, flow angle was largest at the hub and increased as flow approached the engine. The magnitude of static-pressure distortion measured along the inlet-duct and extended bullet nose walls increased exponentially as the flow approached the engine. Wall static-pressure distortion was also a function of distortion harmonic.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-79134 , E-9982 , AVRADCOM-TR-79-19
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  • 165
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    JT8D revised high-pressure turbine cooling and other outer air seal program (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The JT8D high pressure turbine was revised to reduce leakage between the blade tip shrouds and the outer air seal, and engine testing was performed to determine the effect on performance. The addition of a second knife-edge on the blade tip shroud, the extension of the honeycomb seal land to cover the added knife-edge and an existing spoiler on the shroud, and a material substitution in the seal support ring to improve thermal growth characteristics are included. A relocation of the blade cooling air discharge to insure adequate cooling flow is required. Significant specific fuel consumption and exhaust gas temperature improvements were demonstrated with the revised turbine in sea level and simulated altitude engine tests. Inspection of the revised seal hardware after these tests showed no unusual wear or degradation.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-159551 , PWA-5515-77
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  • 166
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    Effect of casing treatment on performance of a two-stage high-pressure-ratio fan (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A two-stage fan, previously tested with a solid casing, was tested with a casing with circumferential grooves over the tips of both rotors (casing treatment). Tests were conducted at 80 and 100 percent of design speed with uniform flow. The casing treatment improved the flow range and stall margin significantly without changing the characteristics overall performance curves of total-pressure and efficiency as functions of weight flow, other than extending them to lower weight flows.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TP-1409 , E-8997
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  • 167
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    Turbine engine altitude chamber and flight testing with liquid hydrogen (1979)
    In:  Other Sources
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    Publication Date: 2019-07-27
    Description: In the late fifties the Lewis Research Center evaluated experimentally the use of hydrogen using three different turbojet engines in altitude test chambers. One of these engines was later flown experimentally using liquid hydrogen fuel. This paper is a brief overview of the significant aspects of this exploratory research and gives a few implications of the results to modern turbine engines. A subsequent contract dealing with a positive displacement pump operating on liquid hydrogen is discussed and some aspects of liquid hydrogen propellant systems, reflected by rocket booster experience are treated briefly. Areas requiring further research and technology effort are delineated.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: International Symposium on Hydrogen in Air Transportation; Sept. 11-14, 1979; Stuttgart
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  • 168
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    Identification and dual adaptive control of a turbojet engine (1979)
    In:  Other Sources
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    Publication Date: 2019-07-27
    Description: The objective of this paper is to utilize the design methods of modern control theory to realize a 'dual-adaptive' feedback control unit for a highly non-linear single spool airbreathing turbojet engine. Using a very detailed and accurate simulation of the non-linear engine as the data source, linear operating point models of unspecified dimension are identified. Feedback control laws are designed at each operating point for a prespecified set of sampling rates using sampled-data output regulator theory. The control system sampling rate is determined by an adaptive sampling algorithm in correspondence with turbojet engine performance. The result is a 'dual-adpative' control law that is functionally dependent upon the sampling rate selected and environmental operating conditions. Simulation transients demonstrate the utility of the dual-adaptive design to improve on-board computer utilization while maintaining acceptable levels of engine performance.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Symposium on Identification and System Parameter Estimation; Sept. 24-28, 1979; Darmstadt
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  • 169
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    Structural analysis of hollow blades: Torsional stress analysis of hollow fan blades for aircraft jet engines (1979)
    In:  CASI
    Details
    Publication Date: 2019-08-27
    Description: A torsional stress analysis of hollow fans blades by the finite element method is presented. The fans are considered to be double circular arc blades, hollowed 30 percent, and twisted by a component of the centrifugal force by the rated revolution. The effects of blade hollowing on strength and rigidity are discussed. The effects of reinforcing webs, placed in the hollowed section in varying numbers and locations, on torsional rigidity and the convergence of stresses, are reported. A forecast of the 30 percent hollowing against torsional loadings is discussed.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-75718 , NAL-TR-533
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  • 170
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    Investigation of air stream from combustor-liner air entry holes, 3 (1979)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: Jets flowing from air entry holes of the combustor liner of a gas turbine were investigated. Cold air was supplied through the air entry holes into the primary hot gas flows. The mass flow of the primary hot gas and issuing jets was measured, and the behavior of the air jets was studied by the measurement of the temperature distribution of the gas mixture. The air jets flowing from three circular air entry holes, single streamwise long holes, and two opposing circular holes, parallel to the primary flow were studied along with the effects of jet and gas stream velocities, and of gas temperature. The discharge coefficient, the maximum penetration of the jets, the jet flow path, the mixing of the jets, and temperature distribution across the jets were investigated. Empirical expressions which describe the characteristics of the jets under the conditions of the experiments were formulated.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-75430 , NAL-TR-369
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  • 171
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    Rotor fragment protection program: Statistics on aircraft gas turbine engine rotor failures that occurred in U.S. commercial aviation during 1977 (1979)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-165388 , AD-A102609 , NAPC-PE-23
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  • 172
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    Laser anemometer measurements at the exit of a T63 combustor (1979)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: In the first practical application of laser anemometry to an actual gas turbine engine combustor, the mean velocity and turbulent intensity profiles were measured in a steady-flow combustion rig across an annulus simulating a turbine inlet; to establish a basis for comparison with similar measurements to be made in an operating engine and to confirm current turbine aerodynamics and heat transfer design assumptions. It was necessary to develop a new experimental technique for traversing the annulus due to differential thermal expansion of the cantilevered combustion rig and a new computer-graphics analysis technique for analyzing the velocity histograms due to the high background light intensity. The axial mean velocity and turbulent intensity were uniform across the annulus under all operating conditions and the flow had little or no swirl component. The isothermal mean velocity was doubled by the burning of fuel, however, the isothermal turbulent intensity was relatively unaffected.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Flow in primary, non-rotating passages in turbomachines; Dec 02, 1979 - Dec 07, 1979; New York, NY
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  • 173
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    Preliminary studies of a turbofan engine and fuel system for use with liquid hydrogen (1979)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: A study of design concepts for the application of the properties of LH2 in a turbofan engine for air transport is presented. The study showed the benefits from the reduction of aircraft direct operating cost. Design concepts for the engine fuel delivery and control system, including the engine high pressure fuel pump, were developed and general concept feasibility was demonstrated. Recommendations were made for the advanced development required for design application for both the engine, the fuel delivery, and the control system.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Hydrogen in air transportation; Sep 11, 1979 - Sep 14, 1979; Stuttgart
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  • 174
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    The evaluation of ceramic turbine stators (1979)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: A ceramic turbine stator evaluation program administered by the NASA Lewis Research Center and supported by the Department of Energy is outlined. The objectives of the program are to evaluate the durability of ceramic stators over a highly dynamic automotive gas turbine duty cycle and to assess the capability of current ceramic design methodology to predict the durability of the stators over the selected duty cycle for times in excess of 200 hours. The program also provides an assessment of the ability of the ceramic industry to fabricate complex geometry monolithic stators by near-net-shape forming processes. A summary of results obtained to date is presented and future plans are discussed.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Army Materials Technology Conference; Jul 10, 1979 - Jul 13, 1979; Orcas Island, WA
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  • 175
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    Procedure for pressure contact on high-power semiconductor devices free of thermal fatigue (1979)
    In:  CASI
    Details
    Publication Date: 2019-08-27
    Description: To eliminate thermal fatigue, a procedure for manufacturing semiconductor power devices with pure pressure contact without solid binding was developed. Pressure contact without the use of a solid binding to avoid a limitation of the maximum surface in the contact was examined. A silicon wafer covered with a relatively thick metal layer is imbedded with the aid of a soft silver foil between two identically sized hard contact discs (molybdenum or tungsten) which are rotationally symmetrical. The advantages of this concept are shown for large diameters. The pressure contact was tested successfully in many devices in a large variety of applications.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-75733 , BMFT-FB-T-78-02
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  • 176
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    Effect of forward velocity and crosswind on the reverse-thrust performance of a variable-pitch fan engine (1979)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A full-size variable-pitch fan engine was tested in the Ames 40 by 80 foot wind tunnel to determine the effect of forward velocity and crosswind on reverse-thrust performance. Two flight-type inlet configurations were tested, and a flared fan nozzle was installed as an inlet for reverse-thrust operation. Steady-state reverse-thrust performance was obtained up to 54 m/s (105 knots). An abrupt decrease in reverse thrust occurred at about 30 m/s (60 knots). Reverse thrust was established following forward-to-reverse thrust transients both statically and with forward velocities only up to 30 m/s.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-79059 , E-9873 , AIAA PAPER 79-0105 , Aerospace, Sci. Meeting; Jan 15, 1979 - Jan 17, 1979; New Orleans, LA; United States
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  • 177
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    Applications of velocity potential function to acoustic duct propagation and radiation from inlets using finite element theory (1979)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A finite element velocity potential program was developed to study acoustic wave propagation in complex geometries. For irrotational flows, relatively low sound frequencies, and plane wave input, the finite element solutions showed significant effects of inlet curvature and flow gradients on the attenuation of a given acoustic liner in a realistic variable area turbofan inlet. The velocity potential approach can not be used to estimate the effects of rotational flow on acoustic propagation, since the potential acoustic disturbances propagate at the speed of the media in sheared flow. Approaches are discussed that are being considered for extending the finite element solution to include the far field, as well as the internal portion of the duct. A new matrix partitioning approach is presented that can be incorporated in previously developed programs to allow the finite element calculation to be marched into the far field. The partitioning approach provided a large reduction in computer storage and running times.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-79071 , E-9888 , Aeroacoustics Conf.; Mar 12, 1979 - Mar 14, 1979; Seattle, WA; United States
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  • 178
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    The effect of throttling on forward radiated fan noise (1979)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: A study was undertaken to evaluate the effect of operating line throttling on inlet-arc noise from high speed fans. Experimental measurements on a 1/4-scale fan stage tested in an anechoic chamber, with and without inlet turbulence control devices, were utilized to assess the effect of constant speed throttling on the forward arc radiated noise characteristics. Different effects were observed in different speed ranges with different types of inflow turbulence control. These effects were correlated with some of the current theories on fan noise generation mechanisms, and partial success was achieved in attempting to relate the various theoretical models to the observed trends. The results of this study have an important bearing on estimating the noise characteristics of new fan designs from scaling the measured characteristics of previously tested fans.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 79-0640 , American Institute of Aeronautics and Astronautics, Aeroacoustics Conference; Mar 12, 1979 - Mar 14, 1979; Seattle, WA
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  • 179
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    Performance characteristics of nonaxisymmetric nozzles installed on the F-18 aircraft (1979)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: The Langley Research Center has conducted an experimental program on a model of the F-18 airplane to determine the performance of nonaxisymmetric nozzles relative to the aircraft's baseline axisymmetric nozzle. The performance of a single expansion ramp (ADEN) and two-dimensional convergent-divergent (2-D C-D) nozzle were compared to the baseline axisymmetric nozzles. The effects of vectoring and reversing were also studied. Performance of a modified YF-17 airplane with the ADEN nozzle was also estimated. The results of this investigation indicate that nonaxisymmetric nozzles can be installed on a twin engine fighter airplane with equal or better performance than axisymmetric nozzles. The nonaxisymmetric nozzles also offer potential for innovative and improved aircraft maneuver through thrust vectoring and reversing. The YF-17/ADEN flown as a technology demonstrator would have reduced performance compared to an unmodified YF-17. However, on an equal aircraft weight basis, performance would essentially be equivalent. This study also showed that the YF-17 can serve as a testbed to validate nonaxisymmetric nozzle technology.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 79-0101 , American Institute of Aeronautics and Astronautics, Aerospace Sciences Meeting; Jan 15, 1979 - Jan 17, 1979; New Orleans, LA
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  • 180
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    Lean combustion limits of a confined premixed-prevaporized propane jet (1979)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: An experimental study was carried out to determine the effects of jet velocity and confinement on lean premixed-prevaporized propane/air blowout limits. The combustor consisted of a single hole flameholder within a quartz liner. Five flameholder plates and two quartz liners were used. Lean stability limits were mapped for confined propane jet in cylindrical combustor. Three zones of flame stability were observed depending on the liner and jet Reynolds number and the combustor geometry. At low Reynolds number the combustor was jet stabilized. As the Reynolds number was increased the combustor became either recirculation zone stabilized, or for small recirculation zone step sizes, the combustor was wall stabilized. The factors affecting stability seem to be the Reynolds numbers of the liner and inlet jet along with the flameholder step size. Stability was achieved at both laminar and turbulent conditions.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 79-0538 , American Institute of Aeronautics and Astronautics, Annual Meeting and Technical Display; Feb 06, 1979 - Feb 08, 1979; Washington, DC
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  • 181
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    Calculation of the three-dimensional flow field in supersonic inlets at angle of attack using a bicharacteristic method with discrete shock wave fitting (1979)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: An analysis is presented for calculating the flow field in supersonic mixed-compression aircraft inlets operating at angle of attack. The flow field is computed by a steady three-dimensional bicharacteristic method. The bow shock wave and the reflected internal shock wave system are computed by a three-dimensional discrete shock wave fitting procedure. Viscous and thermal diffusion may be included as source terms in the bicharacteristic method. A production type computer program capable of determining the flow field in a variety of axisymmetric mixed-compression supersonic inlets is available. The results of the present analysis agree well with those produced by the two-dimensional method of characteristics when axisymmetric flow fields are computed. For three-dimensional flow fields, the results of the present analysis agree well with experimental data except in regions of high viscous interaction and boundary layer removal. The present analysis does not compute the boundary layer, nor does it account for boundary layer bleed.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 79-0379 , American Institute of Aeronautics and Astronautics, Aerospace Sciences Meeting; Jan 15, 1979 - Jan 17, 1979; New Orleans, LA
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  • 182
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    A numerical study of jet entrainment effects on the subsonic flow over nozzle afterbodies (1979)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: A viscous-inviscid interaction model has been developed which accounts for jet entrainment effects in the prediction of the subsonic flow over nozzle afterbodies. The jet entrainment model is based on the concept of a weakly interacting shear layer in which the local streamline deflections due to entrainment are accounted for by a displacement-thickness type correction to the inviscid plume boundary. The entire flowfield is solved in an iterative manner to account for the effects on the inviscid external flow of the turbulent boundary layer, turbulent mixing and chemical reactions in the shear layer, and the inviscid jet exhaust flow. The individual components of the computational model are described and numerical results are presented which illustrate the interactive effects of entrainment on the overall flow structure. The validity of the interactive model is assessed by comparisons with data obtained from flowfield measurements on cold-air jet exhausts. Numerical results and experimental data are also given which show the entrainment effects on nozzle boattail drag under various jet exhaust and freestream flow conditions.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 79-0135 , American Institute of Aeronautics and Astronautics, Aerospace Sciences Meeting; Jan 15, 1979 - Jan 17, 1979; New Orleans, LA
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  • 183
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    A summary of NASA/Air Force full scale engine research programs using the F100 engine (1979)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A full scale engine research (FSER) program conducted with the F100 engine is presented. The program mechanism is described and the F100 test vehicles utilized are illustrated. Technology items were addressed in the areas of swirl augmentation, flutter phenomenon, advanced electronic control logic theory, strain gage technology and distortion sensitivity. The associated test programs are described. The FSER approach utilizes existing state of the art engine hardware to evaluate advanced technology concepts and problem areas. Aerodynamic phenomenon previously not considered by design systems were identified and incorporated into industry design tools.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-79267 , E-183 , Joint Propulsion Conf.; Jun 18, 1979 - Jun 20, 1979; Las Vegas, NV; United States
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  • 184
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    Energy efficient aircraft engines (1979)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: The three engine programs that constitute the propulsion portion of NASA's Aircraft Energy Efficiency Program are described, their status indicated, and anticipated improvements in SFC discussed. The three engine programs are: (1) engine component improvement, directed at current engines, (2) energy efficient engine, directed at new turbofan engines, and (3) advanced turboprops, directed at technology for advanced turboprop-powered aircraft with cruise speeds to Mach 0.8. Unique propulsion system interactive ties to the airframe resulting from engine design features to reduce fuel consumption are discussed. Emphasis is placed on the advanced turboprop since it offers the largest potential fuel savings of the three propulsion programs and also has the strongest interactive ties to the airframe.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 79-1861 , American Institute of Aeronautics and Astronautics, Aircraft Systems and Technology Meeting; Aug 20, 1979 - Aug 22, 1979; New York, NY
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  • 185
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    Progress on Variable Cycle Engines (1979)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: Progress in the development and future requirements of the Variable Stream Control Engine (VSCE) are presented. The two most critical components of this advanced system for future supersonic transports, the high performance duct burner for thrust augmentation, and the low jet coannular nozzle were studied. Nozzle model tests substantiated the jet noise benefit associated with the unique velocity profile possible with a coannular nozzle system on a VSCE. Additional nozzle model performance tests have established high thrust efficiency levels only at takeoff and supersonic cruise for this nozzle system. An experimental program involving both isolated component and complete engine tests has been conducted for the high performance, low emissions duct burner with good results and large scale testing of these two components is being conducted using a F100 engine as the testbed for simulating the VSCE. Future work includes application of computer programs for supersonic flow fields to coannular nozzle geometries, further experimental testing with the duct burner segment rig, and the use of the Variable Cycle Engine (VCE) Testbed Program for evaluating the VSCE duct burner and coannular nozzle technologies.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 79-1312 , AIAA, SAE, and ASME, Joint Propulsion Conference; Jun 18, 1979 - Jun 20, 1979; Las Vegas, NV
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  • 186
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    Multivariable control altitude demonstration on the F100 turbofan engine (1979)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: The control system designed under the Multivariable Control Synthesis (MVCS) program for the F100 turbofan engine is described. The MVCS program, applied the linear quadratic regulator (LQR) synthesis methods in the design of a multivariable engine control system to obtain enhanced performance from cross-coupled controls, maximum use of engine variable geometry, and a systematic design procedure that can be applied efficiently to new engine systems. Basic components of the control system, a reference value generator for deriving a desired equilibrium state and an approximate control vector, a transition model to produce compatible reference point trajectories during gross transients, gain schedules for producing feedback terms appropriate to the flight condition, and integral switching logic to produce acceptable steady-state performance without engine operating limit exceedance are described and the details of the F100 implementation presented. The engine altitude test phase of the MVCS program, and engine responses in a variety of test operating points and power transitions are presented.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 79-1204 , AIAA, SAE, and ASME, Joint Propulsion Conference; Jun 18, 1979 - Jun 20, 1979; Las Vegas, NV
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  • 187
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    Laser-optical blade tip clearance measurement system (1979)
    In:  CASI
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    Publication Date: 2019-07-13
    Description: A laser-optical measurement system was developed to measure single blade tip clearances and average blade tip clearances between a rotor and its gas path seal in rotating component rigs and complete engines. The system is applicable to fan, compressor and turbine blade tip clearance measurements. The engine mounted probe is particularly suitable for operation in the extreme turbine environment. The measurement system consists of an optical subsystem, an electronic subsystem and a computing and graphic terminal. Bench tests and environmental tests were conducted to confirm operation at temperatures, pressures, and vibration levels typically encountered in an operating gas turbine engine.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-81376 , Ann. Intern. Gas Turbine Conf.; Mar 09, 1980 - Mar 13, 1980; New Orleans
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  • 188
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    NASA broad-specification fuels combustion technology program: Status and description (1979)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The program presented is a contracted effort to evolve and demonstrate the technology required to utilize broad-specification fuels in current and next generation commercial Conventional Takeoff and Landing aircraft engines, and to verify this technology in full-scale engine tests in 1983. The program consists of three phases: Combustor Concept Screening, Combustor Optimization Testing, and Engine Verification Testing. The development and screening of the combustion system designs for the CF6-80 engine and the JT9D-7 engine, respectively, in high-pressure sector test rigs are reported.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-79315 , E-272 , Ann. Intern. Gas Turbine Conf.; Mar 09, 1980 - Mar 13, 1980; New Orleans
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  • 189
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    Engine component improvement program: Performance improvement (1979)
    In:  CASI
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    Publication Date: 2019-07-13
    Description: Fuel consumption of commercial aircraft is considered. Fuel saving and retention components for new production and retrofit of JT9D, JT8D, and CF6 engines are reviewed. The manner in which the performance improvement concepts were selected for development and a summary of the current status of each of the 16 selected concepts are discussed.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-79304 , E-256 , Aerospace Sci. Meeting; Jan 14, 1980 - Jan 16, 1980; Pasadena, CA; United States
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  • 190
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    Aeropropulsion 1979 (1979)
    In:  CASI
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    Publication Date: 2019-07-13
    Description: State of the art technology in aeronautical propulsion is assessed. Noise and air pollution control techniques, advances in supersonic propulsion for transport aircraft, and composite materials and structures for reliable engine components are covered along with engine design for improved fuel consumption.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CP-2092 , E-079 , May 15, 1979 - May 16, 1979; Cleveland
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  • 191
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    An overview of NASA research on positive displacement type general aviation engines (1979)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: The paper surveys the current status of the aviation positive displacement engine programs underway at the NASA Lewis Research Center. The program encompasses conventional, lightweight diesel, and rotary combustion engines. Attention is given to topics such as current production type engine improvement, cooling drag reduction, fuel injection, and experimental and theoretical combustion studies. It is shown that the program's two major technical thrusts are directed toward lean operation of current production type spark ignition engines and advanced alternative engine concepts. Finally, an Otto cycle computer model is also covered.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 79-1824 , American Institute of Aeronautics and Astronautics, Aircraft Systems and Technology Meeting; Aug 20, 1979 - Aug 22, 1979; New York, NY
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  • 192
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    Combustor modelling for scramjet engines (1979)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: A system of computer programs is being developed to analyse and predict the complex flow fields found in hydrogen-fueled scramjet combustors. Each program is designed to solve the governing equation system for the type of flow present in a particular combustor region. A two-dimensional parabolic program has been found to be valuable in the development and experimental evaluation of turbulence and chemistry models for supersonic flow, and in the development of a program to model supersonic flow downstream of the fuel injection struts by means of solutions to the three-dimensional parabolic Navier-Stokes equations and species equations. A partially elliptic code has been derived to account for local subsonic flow regions, and fully elliptic programs have been developed by the consideration of streamwise diffusion effects for the recirculating flow fields near transverse fuel injectors. The programs are currently being applied to problems of scramjet engine development.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NATO, AGARD, Specialists'' Meeting on Combustor Modelling; Oct 03, 1979 - Oct 05, 1979; Cologne
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  • 193
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    The effect of fuel sprays on emissions from a gas turbine combustor (1979)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: A research gas turbine combustor which allows for independent control of drop size, fuel/air ratio, air inlet temperature, pressure, reference velocity, and residence time has been used to study the influence of fuel spray characteristics on primary zone emissions. Local concentrations of oxides of nitrogen, carbon monoxide and unburned hydrocarbons at various locations in the flow, local gas temperature, gas velocity, and the turbulence intensity (measured with laser velocimetry) are obtained. A comprehensive data analysis program to compute the local fuel/air ratio and the sum of the mole fractions of the species present confirms the validity of the emissions data. Increasing drop size is correlated with an increase in unburned hydrocarbons, while increasing residence time is associated with sharp decreases in hydrocarbons and carbon monoxide and an increase in oxides of nitrogen.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 79-1321 , AIAA, SAE, and ASME, Joint Propulsion Conference; Jun 18, 1979 - Jun 20, 1979; Las Vegas, NV
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  • 194
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    Lean, premixed, prevaporized combustion for aircraft gas turbine engines (1979)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: The application of lean, premixed, prevaporized combustion to aircraft gas turbine engine systems can result in benefits in terms of superior combustion performance, improved combustor and turbine durability, and environmentally acceptable pollutant emissions. Lean, premixed, prevaporized combustion is particularly attractive for reducing the oxides of nitrogen emissions during high altitude cruise. The NASA Stratospheric Cruise Emission Reduction Program will evolve and demonstrate lean, premixed, prevaporized combustion technology for aircraft engines. This multiphased program is described. In addition, the various elements of the Fundamental Studies Phase of the program are reviewed, and results to date of many of these studies are summarized.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 79-1318 , AIAA, SAE, and ASME, Joint Propulsion Conference; Jun 18, 1979 - Jun 20, 1979; Las Vegas, NV
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  • 195
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    Static test of a large scale swivel nozzle thrust deflector (1979)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: Experimental results from a swivel nozzle thrust deflector test program are presented. The deflector was installed behind a 36-inch fan with a tip turbine hot gas drive. The maximum nozzle pressure ratio was 1.2. Nozzle thrust and flow coefficients are presented for a range of vectoring angles. The results are also compared to small scale cold flow test results. The comparison suggests a need for accurate simulation of nozzle entry pressure and temperature profiles on model tests.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 79-1285 , AIAA, SAE, and ASME, Joint Propulsion Conference; Jun 18, 1979 - Jun 20, 1979; Las Vegas, NV
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  • 196
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    Combined pressure and temperature distortion effects on internal flow of a turbofan engine (1979)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: The flow characteristics obtained experimentally for the compression of a 2-spool TF30-P-3 turbofan engine operating with 180 grad combined pressure and temperature distortion in the inlet flow are presented. The analytical model (Mazzawy and Banks, 1976), 'tuned' during Lewis testing, was used for pretest predictions of the effects that these distortions would have on the engine flow characteristics and the limiting distortion values. The effect of inlet flow distortion on the performance of the engine is discussed, including: (1) the flow between a screen mounted in the inlet duct and the inlet guide vanes; (2) the flow through the compression system; and (3) the effects of the combined distortion and its orientation on the compressor stability limits. It is concluded that the model used in this program was capable of predicting the effects of total pressure, total temperature and combined total pressure-total temperature distortions in terms of flow profiles, inlet flow angles and attenuation of the distortions through the compressor system. It was also capable of predicting the trends of the limiting values experienced with various orientations of the combined distortions.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 79-1309 , AIAA, SAE, and ASME, Joint Propulsion Conference; Jun 18, 1979 - Jun 20, 1979; Las Vegas, NV
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  • 197
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    Effects of air injection on a turbocharged Teledyne Continental Motors TSIO-360-C engine (1979)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: Results are presented for tests performed to assess the effects of exhaust manifold injection air flow rate on emissions and on exhaust gas temperature and turbine inlet temperature for a range of engine operating conditions (speed, torque, and fuel-air ratios) of a fuel-injected turbocharged six-cylinder air-cooled Teledyne Continental Motors TSIO-360-C engine. Air injection into the exhaust gas at 80 F resulted in a decrease in hydrocarbons and carbon monoxide while exceeding the maximum recommended turbine inlet temperature of 1650 F at the full rich mixture of the engine. The EPA standards could be met within present turbine inlet temperature limits using commercially available air pumps, provided that the fuel-air ratios were leaned in the taxi, climb, and approach modes.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: SAE PAPER 790607 , Society of Automotive Engineers, Business Aircraft Meeting and Exposition; Apr 03, 1979 - Apr 06, 1979; Wichita, KS
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  • 198
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    Wind tunnel performance of four energy efficient propellers designed for Mach 0.8 cruise (1979)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: For the advanced turboprop to be competitive with proposed advanced turbofan-powered aircraft, it must have high propulsive efficiency at Mach 0.8 cruise above 9.144-km altitude with an acceptable cabin noise environment. Four 8-bladed propeller models are designed employing various concepts to reduce compressibility losses. Wind tunnel tests are conducted at zero model incidence to the free-stream flow. Aerodynamic and acoustic test results are presented and discussed. It is shown that the aeroacoustically designed configuration (SR-3) with 45 deg of tip sweep and an area-ruled spinner yields the highest propulsive efficiency (78.7% at Mach 0.8, 3.06 advance ratio, and 1.7 power coefficient), with an improvement of about 3% over the straight bladed configuration (SR-2, with zero-degree sweep). The phase-interference concept for noise reduction used in SR-3 yields about 5-6 dB reduction as compared to SR-2.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: SAE PAPER 790573 , Society of Automotive Engineers, Business Aircraft Meeting and Exposition; Apr 03, 1979 - Apr 06, 1979; Wichita, KS
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  • 199
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    A review of Curtiss-Wright rotary engine developments with respect to general aviation potential (1979)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: Aviation related rotary (Wankel-type) engine tests, possible growth directions and relevant developments at Curtiss-Wright have been reviewed. Automotive rotary engines including stratified charge are described and flight test results of rotary aircraft engines are presented. The current 300 HP engine prototype shows basic durability and competitive performance potential. Recent parallel developments have separately confirmed the geometric advantages of the rotary engine for direct injected unthrottled stratified charge. Specific fuel consumption equal to or better than pre- or swirl-chamber diesels, low emission and multi-fuel capability have been shown by rig tests of similar rotary engine.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: SAE PAPER 790621 , Society of Automotive Engineers, Business Aircraft Meeting and Exposition; Apr 03, 1979 - Apr 06, 1979; Wichita, KS
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  • 200
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    Determination of cooling air mass flow for a horizontally-opposed aircraft engine installation (1979)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: The relationship between the amount of cooling air flow and the corresponding flow pressure difference across an aircraft engine was investigated in flight and on the ground. The flight test results were consistent with theory, but indicated a significant installation leakage problem. A ground test blower system was used to identify and reduce the leakage. The correlation between ground test cell determined engine orifice characteristics and flight measurements showed good agreement if the engine pressure difference was based on total pressure rather than static pressure.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: SAE PAPER 790609 , Society of Automotive Engineers, Business Aircraft Meeting and Exposition; Apr 03, 1979 - Apr 06, 1979; Wichita, KS
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