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  • 1
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    Cooling Duct Analysis for Transpiration/Film Cooled Liquid Propellant Rocket Engines (1996)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The development of a low cost space transportation system requires that the propulsion system be reusable, have long life, with good performance and use low cost propellants. Improved performance can be achieved by operating the engine at higher pressure and temperature levels than previous designs. Increasing the chamber pressure and temperature, however, will increase wall heating rates. This necessitates the need for active cooling methods such as film cooling or transpiration cooling. But active cooling can reduce the net thrust of the engine and add considerably to the design complexity. Recently, a metal drawing process has been patented where it is possible to fabricate plates with very small holes with high uniformity with a closely specified porosity. Such a metal plate could be used for an inexpensive transpiration/film cooled liner to meet the demands of advanced reusable rocket engines, if coolant mass flow rates could be controlled to satisfy wall cooling requirements and performance. The present study investigates the possibility of controlling the coolant mass flow rate through the porous material by simple non-active fluid dynamic means. The coolant will be supplied to the porous material by series of constant geometry slots machined on the exterior of the engine.
    Keywords: Spacecraft Propulsion and Power
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 2
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    Effects of nozzle lip geometry on spray atomization and emissions advanced gas turbine combustors (1991)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A parametric study is conducted to investigate the effect of nozzle lip geometry on nozzle fuel distribution, emissions and temperature distribution for a rich burn section of a rich burn/quick quench/lean burn combustor. It is seen that the nozzle lip geometry greatly affects the fuel distribution, emissions and temperature distribution. It is determined that at an equivalence ratio of 1.6 the NO concentration could be lowered by a factor greater than three by changing the nozzle lip geometry.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 91-2201
    Format: text
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    NASA TECHNICAL REPORTS
  • 3
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    Effect of vane twist on the performance of dome swirlers for gas turbine airblast atomizers (1990)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: For advanced gas turbine engines, two combustor systems, the lean premixed/prevaporized (LPP) and the rich burn/quick quench/lean burn (RQL) offer great potential for reducing NO(x) emissions. An important consideration for either concept is the development of an advanced fuel injection system that will provide a stable, efficient, and very uniform combustion system over a wide operating range. High-shear airblast fuel injectors for gas turbine combustors have exhibited superior atomization and mixing compared with pressure-atomizing fuel injectors. This improved mixing has lowered NO(x) emissions and the pattern factor, and has enabled combustors to alternate fuels while maintaining a stable, efficient combustion system. The performance of high-shear airblast fuel injectors is highly dependent on the design of the dome swirl vanes. The type of swirl vanes most widely used in gas turbine combustors are usually flat for ease of manufacture, but vanes with curvature will, in general, give superior aerodynamic performance. The design and performance of high-turning, low-loss curved dome swirl vanes with twist along the span are investigated. The twist induces a secondary vortex flow pattern which will improve the atomization of the fuel, thereby producing a more uniform fuel-air distribution. This uniform distribution will increase combustion efficiency while lowering NO(x) emissions. A systematic swirl vane design system is presented based on one-, two-, and three-dimensional flowfield calculations, with variations in vane-turning angle, rate of turning, vane solidity, and vane twist as design parameters.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA PAPER 90-1955
    Format: text
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    NASA TECHNICAL REPORTS
  • 4
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    Emissions reduction by varying the swirler airflow split in advanced gas turbine combustors (1992)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: A rich burn/quick mix/lean burn (RQL) combustor concept for reducing pollutant emissions is currently under investigation at the NASA Lewis Research Center. The current study investigates the effect of varying the mass flow rate split between the swirler passages for an equivalance ratio of 2.0 on fuel distribution, temperature distribution, and emissions for the fuel nozzle/rich burn section of an RQL combustor. It is seen that optimizing these parameters can substantially improve combustor performance and reduce combustor emissions. The optimal mass flow rate split for reducing NO(x) emissions based on the numerical study was the same as found by experiment.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: ASME PAPER 92-GT-110 , ; 8 p.|ASME, International Gas Turbine and Aeroengine Congress and Exposition; Jun 01, 1992 - Jun 04, 1992; Cologne; Germany
    Format: text
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    NASA TECHNICAL REPORTS
  • 5
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    Effect of vane twist on the performance of dome swirlers for gas turbine airblast atomizers (1990)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: For advanced gas turbine engines, two combustor systems, the lean premixed/prevaporized (LPP) and the rich burn/quick quench/lean burn (RQL) offer great potential for reducing NO(x) emissions. An important consideration for either concept is the development of an advanced fuel injection system that will provide a stable, efficient, and very uniform combustion system over a wide operating range. High-shear airblast fuel injectors for gas turbine combustors have exhibited superior atomization and mixing compared with pressure-atomizing fuel injectors. This improved mixing has lowered NO(x) emissions and the pattern factor, and has enabled combustors to alternate fuels while maintaining a stable, efficient combustion system. The performance of high-shear airblast fuel injectors is highly dependent on the design of the dome swirl vanes. The type of swirl vanes most widely used in gas turbine combustors are usually flat for ease of manufacture, but vanes with curvature will, in general, give superior aerodynamic performance. The design and performance of high-turning, low-loss curved dome swirl vanes with twist along the span are investigated. The twist induces a secondary vortex flow pattern which will improve the atomization of the fuel, thereby producing a more uniform fuel-air distribution. This uniform distribution will increase combustion efficiency while lowering NO(x) emissions. A systematic swirl vane design system is presented based on one-, two-, and three-dimensional flowfield calculations, with variations in vane-turning angle, rate of turning, vane solidity, and vane twist as design parameters.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-TM-103195 , E-5589 , NAS 1.15:103195 , AIAA PAPER 90-1955 , Joint Propulsion Conference; Jul 16, 1990 - Jul 18, 1990; Orlando, FL; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 6
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    Twisted Vanes Would Enhance Fuel/Air Mixing In Turbines (1994)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Computations of flow show performance of high-shear airblast fuel injector in gas-turbine engine enhanced by use of appropriately proportioned twisted (instead of flat) dome swirl vanes. Resultant more nearly uniform fuel/air mixture burns more efficiently, emitting smaller amounts of nitrogen oxides. Twisted-vane high-shear airblast injectors also incorporated into paint sprayers, providing advantages of low pressure drop characteristic of airblast injectors in general and finer atomization of advanced twisted-blade design.
    Keywords: MECHANICS
    Type: LEW-15392 , NASA Tech Briefs (ISSN 0145-319X); 18; 4; P. 64
    Format: text
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    NASA TECHNICAL REPORTS
  • 7
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    Computation of the flow field in an annular gas turbine combustor (1993)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The KIVA-II code was modified to calculate the 3D flow field in a typical annular gas turbine combustor. The airblast fuel nozzle, cooling baffle, cooling slots, primary and dilution jets, and effusion cooling (bleed) pads were accounted for in this calculation. The turbulence and combustion were modeled using the k-epsilon model and laminar Arrhenius kinetics, respectively. The fuel was modeled as an evaporating liquid spray. The results illustrate the complicated flow fields present in such combustors. From the results obtained to date it appears that the modified KIVA-II code can be used to study the effects of different annular combustor designs and operating conditions.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 93-2074 , AIAA, SAE, ASME, and ASEE, Joint Propulsion Conference and Exhibit; Jun 28, 1993 - Jun 30, 1993; Monterey, CA; United States|; 13 p.
    Format: text
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