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  • 1
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    Modeling of premixing-prevaporizing fuel-air mixing passages (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The development of a computer program for the analytical prediction of the distribution of liquid and vapor fuel in the premixing-prevaporizing passage by the direct injection method is described. The technical approach adopted for this program is to separate the problem into three parts each with its own computer code. These three parts are: calculation of the two-dimensional or axisymmetric air flow; calculation of the three-dimensional fuel droplet evaporation; and calculation of the fuel vapor diffusion. This method of approach is justified because premixing passages operate at lean equivalence ratios. Hence, a weak interaction assumption can be made wherein the airflow can affect the fuel droplet behavior but the fuel droplet behavior does not affect the airflow.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Lewis Res. Center Premixed Prevaporized Combustor Technol. Forum; p 57-65
    Format: application/pdf
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  • 2
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    Lean Stability augmentation study (1979)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: An analytical and experimental program was conducted to investigate techniques and develop technology for improving the lean combustion limits of premixing, prevaporizing combustors applicable to gas turbine engine main burners. Three concepts for improving lean stability limits were selected for experimental evaluation among twelve approaches considered. Concepts were selected on the basis of the potential for improving stability limits and achieving emission goals, the technological risks associated with development of practical burners employing the concepts, and the penalties to airline direct operating costs resulting from decreased combustor performance, increased engine cost, increased maintenance cost and increased engine weight associated with implementation of the concepts. Tests of flameholders embodying the selected concepts were conducted.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Lewis Res. Center Premixed Prevaporized Combustor Technol. Forum; p 163-177
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    NASA TECHNICAL REPORTS
  • 3
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    Longitudinal Mode Aeroengine Combustion Instability: Model and Experiment (2001)
    In:  CASI
    Details
    Publication Date: 2017-09-27
    Description: Combustion instabilities in gas turbine engines are most frequently encountered during the late phases of engine development, at which point they are difficult and expensive to fix. The ability to replicate an engine-traceable combustion instability in a laboratory-scale experiment offers the opportunity to economically diagnose the problem more completely (to determine the root cause), and to investigate solutions to the problem, such as active control. The development and validation of active combustion instability control requires that the casual dynamic processes be reproduced in experimental test facilities which can be used as a test bed for control system evaluation. This paper discusses the process through which a laboratory-scale experiment and be designed to replicate an instability observed in a developmental engine. The scaling process used physically-based analyses to preserve the relevant geometric, acoustic, and thermo-fluid features, ensuring that results achieved in the single-nozzle experiment will be scalable to the engine.
    Keywords: Inorganic, Organic and Physical Chemistry
    Type: Active Control Technology for Enhanced Performance Operational Capabilities of Military Aircraft, Land Vehicles and Sea Vehicles; 5-1 - 5-9; RTO-MP-051
    Format: text
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    NASA TECHNICAL REPORTS
  • 4
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    Analytical modeling of operating characteristics of premixing-prevaporizing fuel-air mixing passages. Volume 2: User's manual (1982)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A user's manual describing the operation of three computer codes (ADD code, PTRAK code, and VAPDIF code) is presented. The general features of the computer codes, the input/output formats, run streams, and sample input cases are described.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-167990-VOL-2 , NAS 1.26:167990-V0L-2 , R82-915362-40-VOL-2
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  • 5
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    Analytical modeling of operating characteristics of premixing-prevaporizing fuel-air mixing passages. Volume 1: Analysis and results (1982)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A model for predicting the distribution of liquid fuel droplets and fuel vapor in premixing-prevaporizing fuel-air mixing passages of the direct injection type is reported. This model consists of three computer programs; a calculation of the two dimensional or axisymmetric air flow field neglecting the effects of fuel; a calculation of the three dimensional fuel droplet trajectories and evaporation rates in a known, moving air flow; a calculation of fuel vapor diffusing into a moving three dimensional air flow with source terms dependent on the droplet evaporation rates. The fuel droplets are treated as individual particle classes each satisfying Newton's law, a heat transfer, and a mass transfer equation. This fuel droplet model treats multicomponent fuels and incorporates the physics required for the treatment of elastic droplet collisions, droplet shattering, droplet coalescence and droplet wall interactions. The vapor diffusion calculation treats three dimensional, gas phase, turbulent diffusion processes. The analysis includes a model for the autoignition of the fuel air mixture based upon the rate of formation of an important intermediate chemical species during the preignition period.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-167990-VOL-1 , NAS 1.26:167990-VOL-1 , R82-915362-40-VOL-1
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  • 6
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    Lean stability augmentation study (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: An analytical conceptual design study and an experimental test program were conducted to investigate techniques and develop technology for improving the lean combustion limits of premixing, prevaporizing combustors applicable to gas turbine engine main burners. The use of hot gas pilots, catalyzed flameholder elements, and heat recirculation to augment lean stability limits was considered in the conceptual design study. Tests of flameholders embodying selected concepts were conducted at a pressure of 10 arm and over a range of entrance temperatures simulating conditions to be encountered during stratospheric cruise. The tests were performed using an axisymmetric flametube test rig having a nominal diameter of 10.2 cm. A total of sixteen test configurations were examined in which lean blowout limits, pollutant emission characteristics, and combustor performance were evaluated. The use of a piloted perforated plate flameholder employing a pilot fuel flow rate equivalent to 4 percent of the total fuel flow at a simulated cruise condition resulted in a lean blowout equivalence ratio of less than 0.25 with a design point (T sub zero = 600k, Phi = 0.6) NOx emission index of less than 1.0 g/kg.
    Keywords: INORGANIC AND PHYSICAL CHEMISTRY
    Type: NASA-CR-159536 , UTRC/R79-914104-18
    Format: application/pdf
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  • 7
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    Fuel-injector/air-swirl characterization (1985)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The objectives of this program are to establish an experimental data base documenting the behavior of gas turbine engine fuel injector sprays as the spray interacts with the swirling gas flow existing in the combustor dome, and to conduct an assessment of the validity of current analytical techniques for predicting fuel spray behavior. Emphasis is placed on the acquisition of data using injector/swirler components which closely resemble components currently in use in advanced aircraft gas turbine engines, conducting tests under conditions that closely simulate or closely approximate those developed in actual combustors, and conducting a well-controlled experimental effort which will comprise using a combination of low-risk experiments and experiments requiring the use of state-of-the-art diagnostic instrumentation. Analysis of the data is to be conducted using an existing, TEACH-type code which employs a stochastic analysis of the motion of the dispersed phase in the turbulent continuum flow field.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Lewis Research Center, Turbine Engine Hot Section Technology, 1985; p 109-117
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  • 8
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    Fuel-injector/air-swirl characterization (1988)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Experimental data on the characteristics of the spray produced by a gas-turbine engine airblast fuel injector are reported. The data acquired include the mass-flux distribution measured by use of a high-resolution spray patternator; the gas-phase velocity field measured by use of a two-component laser Doppler velocimeter, and the liquid droplet size and velocity distributions measured by use of a single-component phase-Doppler anemometer. The data are intended for use in assessments of two-phase flow computational methods as applied to combustor design procedures.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-180864 , NAS 1.26:180864
    Format: application/pdf
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  • 9
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    Mechanism of instabilities of exothermic hypersonic blunt-body flows (1971)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Exothermic hypersonic blunt body flow periodic instability mechanism, using ballistic range with schlieren photographic equipment
    Keywords: THERMODYNAMICS AND COMBUSTION
    Type: ; ADEMIE DES SCIENCES
    Format: text
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  • 10
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    Experimental Replication of an Aeroengine Combustion Instability (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Combustion instabilities in gas turbine engines are most frequently encountered during the late phases of engine development, at which point they are difficult and expensive to fix. The ability to replicate an engine-traceable combustion instability in a laboratory-scale experiment offers the opportunity to economically diagnose the problem (to determine the root cause), and to investigate solutions to the problem, such as active control. The development and validation of active combustion instability control requires that the causal dynamic processes be reproduced in experimental test facilities which can be used as a test bed for control system evaluation. This paper discusses the process through which a laboratory-scale experiment was designed to replicate an instability observed in a developmental engine. The scaling process used physically-based analyses to preserve the relevant geometric, acoustic and thermo-fluid features. The process increases the probability that results achieved in the single-nozzle experiment will be scalable to the engine.
    Keywords: Aeronautics (General)
    Type: NASA/TM-2000-210250 , E-12370 , NAS 1.15:210250 , International Gas Turbine and Aeroengine Technical Congress; May 08, 2000 - May 11, 2000; Munich; Germany
    Format: application/pdf
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