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  • Aircraft Propulsion and Power
  • 1995-1999  (13)
  • 1950-1954
  • 1945-1949
  • 1930-1934
  • 1996  (13)
Collection
Keywords
Years
  • 1995-1999  (13)
  • 1950-1954
  • 1945-1949
  • 1930-1934
Year
  • 1
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    Flow Coupling Effects in Jet-in-Crossflow Flowfields (1996)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The combustor designer is typically required to design liner orifices that effectively mix air jets with crossflow effluent. CFD combustor analysis is typically used in the design process; however the jets are usually assumed to enter the combustor with a uniform velocity and turbulence profile. The jet-mainstream flow coupling is usually neglected because of the computational expense. This CFD study was performed to understand the effect of jet-mainstream flow coupling, and to assess the accuracy of jet boundary conditions that are commonly used in combustor internal calculations. A case representative of a plenum-fed quick-mix section of a Rich Burn/Quick Mix/Lean Burn combustor (i.e. a jet-mainstream mass-flow ratio of about 3 and a jet-mainstream momentum-flux ratio of about 30) was investigated. This case showed that the jet velocity entering the combustor was very non-uniform, with a low normal velocity at the leading edge of the orifice and a high normal velocity at the trailing edge of the orifice. Three different combustor-only cases were analyzed with uniform inlet jet profile. None of the cases matched the plenum-fed calculations. To assess liner thickness effects, a thin-walled case was also analyzed. The CFD analysis showed the thin-walled jets had more penetration than the thick-walled jets.
    Keywords: Aircraft Propulsion and Power
    Type: NASA-TM-107257 , NAS 1.15:107257 , AIAA Paper 96-2762 , E-10318 , AIAA/ASME/SAE/ASEE Joint Propulsion Conference; Jul 01, 1996 - Jul 03, 1996; Lake Buena Vista, FL; United States
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    NASA TECHNICAL REPORTS
  • 2
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    Effects of Inlet Flow Conditions on Crossflow Jet Mixing (1996)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: An experimental investigation of the effects of mainstream turbulence, mainstream swirl and non-symmetric mass addition has been conducted for the isothermal mixing of multiple jets injected into a confined rectangular crossflow. Jet penetration and mixing in the near field was studied using planar Mie scattering to measure time-averaged mixture fraction distributions. Orifice configurations were used that were optimized for mixing performance based on previous experimental and computational results for a homogeneous approach flow. Mixing effectiveness, determined using a spatial unmixedness parameter based on the variance of the mean jet concentration distributions, was found to be minimally affected by free-stream turbulence but significantly influenced by the addition of swirl to the mainstream. The results for non-symmetric mass addition indicate that the concentration distribution of the flowfield can be tailored if desired.
    Keywords: Aircraft Propulsion and Power
    Type: NASA-TM-107258 , NAS 1.15:107258 , AIAA Paper 96-2881 , E-10319 , Joint Propulsion Conference; Jul 01, 1996 - Jul 03, 1996; Lake Buena Vista, FL; United States
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    NASA TECHNICAL REPORTS
  • 3
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    Flight and Static Exhaust Flow Properties of an F110-GE-129 Engine in an F-16XL Airplane During Acoustic Tests (1996)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The exhaust flow properties (mass flow, pressure, temperature, velocity, and Mach number) of the F110-GE-129 engine in an F-16XL airplane were determined from a series of flight tests flown at NASA Dryden Flight Research Center, Edwards, California. These tests were performed in conjunction with NASA Langley Research Center, Hampton, Virginia (LARC) as part of a study to investigate the acoustic characteristics of jet engines operating at high nozzle pressure conditions. The range of interest for both objectives was from Mach 0.3 to Mach 0.9. NASA Dryden flew the airplane and acquired and analyzed the engine data to determine the exhaust characteristics. NASA Langley collected the flyover acoustic measurements and correlated these results with their current predictive codes. This paper describes the airplane, tests, and methods used to determine the exhaust flow properties and presents the exhaust flow properties. No acoustics results are presented.
    Keywords: Aircraft Propulsion and Power
    Type: NASA-TM-104326 , H-2122 , NAS 1.15:104326
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  • 4
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    Development of an Intelligent Monitoring and Control System for a Heterogeneous Numerical Propulsion System Simulation (1996)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The NASA Numerical Propulsion System Simulation (NPSS) project is exploring the use of computer simulation to facilitate the design of new jet engines. Several key issues raised in this research are being examined in an NPSS-related research project: zooming, monitoring and control, and support for heterogeneity. The design of a simulation executive that addresses each of these issues is described. In this work, the strategy of zooming, which allows codes that model at different levels of fidelity to be integrated within a single simulation, is applied to the fan component of a turbofan propulsion system. A prototype monitoring and control system has been designed for this simulation to support experimentation with expert system techniques for active control of the simulation. An interconnection system provides a transparent means of connecting the heterogeneous systems that comprise the prototype.
    Keywords: Aircraft Propulsion and Power
    Type: NASA-CR-202435 , NAS 1.26:202435
    Format: application/pdf
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  • 5
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    High-speed engine/component performance assessment using exergy and thrust-based methods (1996)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: This investigation summarizes a comparative study of two high-speed engine performance assessment techniques based on energy (available work) and thrust-potential (thrust availability). Simple flow-fields utilizing Rayleigh heat addition and one-dimensional flow with friction are used to demonstrate the fundamental inability of conventional energy techniques to predict engine component performance, aid in component design, or accurately assess flow losses. The use of the thrust-based method on these same examples demonstrates its ability to yield useful information in all these categories. Energy and thrust are related and discussed from the stand-point of their fundamental thermodynamic and fluid dynamic definitions in order to explain the differences in information obtained using the two methods. The conventional definition of energy is shown to include work which is inherently unavailable to an aerospace Brayton engine. An engine-based energy is then developed which accurately accounts for this inherently unavailable work; performance parameters based on this quantity are then shown to yield design and loss information equivalent to the thrust-based method.
    Keywords: Aircraft Propulsion and Power
    Type: NASA-CR-198271 , NAS 1.26:198271
    Format: application/pdf
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  • 6
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    Task 7: Endwall treatment inlet flow distortion analysis (1996)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The overall objective of this study was to develop a 3-D numerical analysis for compressor casing treatment flowfields, and to perform a series of detailed numerical predictions to assess the effectiveness of various endwall treatments for enhancing the efficiency and stall margin of modern high speed fan rotors. Particular attention was given to examining the effectiveness of endwall treatments to counter the undesirable effects of inflow distortion. Calculations were performed using three different gridding techniques based on the type of casing treatment being tested and the level of complexity desired in the analysis. In each case, the casing treatment itself is modeled as a discrete object in the overall analysis, and the flow through the casing treatment is determined as part of the solution. A series of calculations were performed for both treated and untreated modern fan rotors both with and without inflow distortion. The effectiveness of the various treatments were quantified, and several physical mechanisms by which the effectiveness of endwall treatments is achieved are discussed.
    Keywords: Aircraft Propulsion and Power
    Type: NASA-CR-195468 , NAS 1.26:195468 , E-9647
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  • 7
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    Mixed composition materials suitable for vacuum web sputter coating (1996)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Ion beam sputter deposition techniques were used to investigate simultaneous sputter etching of two component targets so as to produce mixed composition films. Although sputter deposition has been largely confined to metals and metal oxides, at least one polymeric material, poly-tetra-fluorethylene, has been demonstrated to produce sputtered fragments which repolymerize upon deposition to produce a highly cross-linked fluoropolymer resembling that of the parent target Fluoropolymer-filled silicon dioxide and fluoropolymer-filled aluminum oxide coatings have been deposited by means of ion beam sputter coat deposition resulting in films having material properties suitable for aerospace and commercial applications. The addition of fluoropolymer to silicon dioxide films was found to increase the hydrophobicity of the resulting mixed films; however, adding fluoropolymer to aluminum oxide films resulted in a reduction in hydrophobicity, thought to be caused by aluminum fluoride formation.
    Keywords: Aircraft Propulsion and Power
    Type: NASA-TM-107264 , NAS 1.15:107264 , E-10329 , Annual Technical Conference; May 08, 1996 - May 10, 1996; Philadelphia, PA; United States
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  • 8
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    High Stability Engine Control (HISTEC) (1996)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Future aircraft turbine engines, both commercial and military, must be able to successfully accommodate expected increased levels of steady-state and dynamic engine-face distortion. The current approach of incorporating a sufficient component design stall margin to tolerate these increased levels of distortion would significantly reduce performance. The objective of the High Stability Engine Control (HISTEC) program is to design, develop, and flight demonstrate an advanced, high-stability, integrated engine control system that uses measurement-based, real-time estimates of distortion to enhance engine stability. The resulting distortion tolerant control reduces the required design stall margin, with a corresponding increase in performance and decrease in fuel burn. The HISTEC concept, consisting of a Distortion Estimation System and a Stability Management Control, has been designed and developed. The Distortion Estimation System uses a small number of high-response pressure sensors at the engine face to calculate indicators of the type and extent of distortion in real time. The Stability Management Control, through direct control of the fan and compressor pressure ratio, accommodates the distortion by transiently increasing the amount of stall margin available based on information from the Distortion Estimation System. Simulation studies have shown the HISTEC distortion tolerant control is able to successfully estimate and accommodate time-varying distortion. Currently, hardware and software systems necessary for flight demonstration of the HISTEC concept are being designed and developed. The HISTEC concept will be flight tested in early 1997.
    Keywords: Aircraft Propulsion and Power
    Type: NASA-TM-107272 , E-10339 , NAS 1.15:107272 , AIAA Paper 96-2586 , Joint Propulsion Conference; Jul 01, 1996 - Jul 03, 1996; Lake Buena Vista, FL; United States
    Format: application/pdf
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  • 9
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    Mixing of Multiple Jets with a Confined Subsonic Crossflow in a Cylindrical Duct (1996)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: This paper summarizes NASA-supported experimental and computational results on the mixing of a row of jets with a confined subsonic crossflow in a cylindrical duct. The studies from which these results were derived investigated flow and geometric variations typical of the complex 3-D flowfield in the combustion chambers in gas turbine engines. The principal observations were that the momentum-flux ratio and the number of orifices were significant variables. Jet penetration was critical, and jet penetration decreased as either the number of orifices increased or the momentum-flux ratio decreased. It also appeared that jet penetration remained similar with variations in orifice size, shape, spacing, and momentum-flux ratio when the number of orifices was proportional to the square-root of the momentum-flux ratio. In the cylindrical geometry, planar variances are very sensitive to events in the near wall region, so planar averages must be considered in context with the distributions. The mass-flow ratios and orifices investigated were often very large (mass-flow ratio greater than 1 and ratio of orifice area-to-mainstream cross-sectional area up to 0.5), and the axial planes of interest were sometimes near the orifice trailing edge. Three-dimensional flow was a key part of efficient mixing and was observed for all configurations. The results shown also seem to indicate that non-reacting dimensionless scalar profiles can emulate the reacting flow equivalence ratio distribution reasonably well. The results cited suggest that further study may not necessarily lead to a universal 'rule of thumb' for mixer design for lowest emissions, because optimization will likely require an assessment for a specific application.
    Keywords: Aircraft Propulsion and Power
    Type: NASA-TM-107185 , NAS 1.15:107185 , ASME-96-GT-482 , E-9996 , Gas Turbine and Aeroengine Congress; Jun 10, 1996 - Jun 13, 1996; Birmingham; United Kingdom
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  • 10
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    Seals Code Development Workshop (1996)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Seals Workshop of 1995 industrial code (INDSEAL) release include ICYL, GCYLT, IFACE, GFACE, SPIRALG, SPIRALI, DYSEAL, and KTK. The scientific code (SCISEAL) release includes conjugate heat transfer and multidomain with rotordynamic capability. Several seals and bearings codes (e.g., HYDROFLEX, HYDROTRAN, HYDROB3D, FLOWCON1, FLOWCON2) are presented and results compared. Current computational and experimental emphasis includes multiple connected cavity flows with goals of reducing parasitic losses and gas ingestion. Labyrinth seals continue to play a significant role in sealing with face, honeycomb, and new sealing concepts under investigation for advanced engine concepts in view of strict environmental constraints. The clean sheet approach to engine design is advocated with program directions and anticipated percentage SFC reductions cited. Future activities center on engine applications with coupled seal/power/secondary flow streams.
    Keywords: Aircraft Propulsion and Power
    Type: NASA-CP-10181 , E-9945 , NAS 1.55:10181 , Seals Code Development Workshop; Jun 14, 1995 - Jun 15, 1995; Cleveland, OH; United States
    Format: application/pdf
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