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  • Aircraft Propulsion and Power
  • 1995-1999  (51)
  • 1950-1954  (3)
  • 1945-1949  (7)
  • 1930-1934  (1)
  • 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
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 2
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    An Evaluation of Aircraft Emissions Inventory Methodology by Comparisons with Reported Airline Data (1999)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: This report provides results of work done to evaluate the calculation methodology used in generating aircraft emissions inventories. Results from the inventory calculation methodology are compared to actual fuel consumption data. Results are also presented that show the sensitivity of calculated emissions to aircraft payload factors. Comparisons of departures made, ground track miles flown and total fuel consumed by selected air carriers were made between U.S. Dept. of Transportation (DOT) Form 41 data reported for 1992 and results of simplified aircraft emissions inventory calculations. These comparisons provide an indication of the magnitude of error that may be present in aircraft emissions inventories. To determine some of the factors responsible for the errors quantified in the DOT Form 41 analysis, a comparative study of in-flight fuel flow data for a specific operator's 747-400 fleet was conducted. Fuel consumption differences between the studied aircraft and the inventory calculation results may be attributable to several factors. Among these are longer flight times, greater actual aircraft weight and performance deterioration effects for the in-service aircraft. Results of a parametric study on the variation in fuel use and NOx emissions as a function of aircraft payload for different aircraft types are also presented.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/CR-1999-209480 , Rept-99B00077 , NAS 1.26:209480
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    NASA TECHNICAL REPORTS
  • 3
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    XV-15 Tiltrotor Low Noise Approach Operations (1999)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Acoustic data have been acquired for the XV-15 tiltrotor aircraft performing approach operations for a variety of different approach profile configurations. This flight test program was conducted jointly by NASA, the U.S. Army, and Bell Helicopter Textron, Inc. (BHTI) in June 1997. The XV-15 was flown over a large area microphone array, which was deployed to directly measure the noise footprint produced during actual approach operations. The XV-15 flew realistic approach profiles that culminated in IGE hover over a landing pad. Aircraft tracking and pilot guidance was provided by a Differential Global Positioning System (DGPS) and a flight director system developed at BHTI. Approach profile designs emphasized noise reduction while maintaining handling qualities sufficient for tiltrotor commercial passenger ride comfort and flight safety under Instrument Flight Rules (IFR) conditions. A discussion of the approach profile design philosophy is provided. Five different approach profiles are discussed in detail -- 3 deg., 6 deg., and 9 deg. approaches, and two very different 3 deg. to 9 deg. segmented approaches. The approach profile characteristics are discussed in detail, followed by the noise footprints and handling qualities. Sound exposure levels are also presented on an averaged basis and as a function of the sideline distance for a number of up-range distances from the landing point. A comparison of the noise contour areas is also provided. The results document the variation in tiltrotor noise due to changes in operating condition, and indicate the potential for significant noise reduction using the unique tiltrotor capability of nacelle tilt.
    Keywords: Aircraft Propulsion and Power
    Type: American Helicopter Society 55th Annual Forum; May 25, 1999 - May 27, 1999; Montreal, Quebec; Canada
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  • 4
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    Multistage Simulations of the GE90 Turbine (1999)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The average passage approach has been used to analyze three multistage configurations of the GE90 turbine. These are a high pressure turbine rig, a low pressure turbine rig and a full turbine configuration comprising 18 blade rows of the GE90 engine at takeoff conditions. Cooling flows in the high pressure turbine have been simulated using source terms. This is the first time a dual-spool cooled turbine has been analyzed in 3D using a multistage approach. There is good agreement between the simulations and experimental results. Multistage and component interaction effects are also presented. The parallel efficiency of the code is excellent at 87.3% using 121 processors on an SGI Origin for the 18 blade row configuration. The accuracy and efficiency of the calculation now allow it to be effectively used in a design environment so that multistage effects can be accounted for in turbine design.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/CR-1999-209311 , E-11880 , NAS 1.26:209311 , Gas Turbine and Aeroengine Congress; Jun 07, 1999 - Jun 10, 1999; Indianapolis, IN; United States
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  • 5
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    Effects of Initial Conditions on a Single Jet in Crossflow (1995)
    In:  CASI
    Details
    Publication Date: 2019-08-15
    Description: An experimental investigation of the effects of jet inlet flow conditions has been conducted for the isothermal mixing of a single jet injected into a crossflow. Jet penetration and mixing was studied using planar Mie scattering to measure time-averaged jet mixture fraction distributions. The effects of 'passive' control methods such as jet 'tabs' and jet swirl are reported. Mixing effectiveness, determined using a spatial unmixedness parameter based on the variance of the mean jet concentration distributions, was compared to a baseline case of a round jet injected into a uniform crossflow. All results are compared at a jet-to-mainstream momentum-flux ratio of 8.5. In the near-field, the mixing rates are similar to, or less than, the baseline configuration using this measure of mixedness. None of the tested configurations appear to significantly augment mixing within a downstream distance of 3 diameters of an equivalent-area round orifice.
    Keywords: Aircraft Propulsion and Power
    Type: NASA-TM-107002 , AIAA Paper 95-2998 , E-9782 , NAS 1.15:107002 , Joint Propulsion Conference and Exhibit; Jul 10, 1995 - Jul 12, 1995; San Diego, CA; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 6
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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
  • 7
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    Numerical Simulation of Multi-Stage Turbomachinery Flows (1999)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: A comprehensive assessment is made of the predictive capability of the average passage flow model as applied to multi-stage axial flow compressors. The average passage flow model describes the time average flow field within a typical passage of a blade row embedded in a multi-stage configuration. In this work data taken within a four and one-half stage large low speed compressor will be used to assess the weakness and strengths of the predictive capabilities of the average passage flow model. The low speed compressor blading is of modern design and employs stators with end-bends. Measurements were made with slow and high response instrumentation. The high response measurements revealed the velocity components of both the rotor and stator wakes. Based on the measured wake profiles it will be argued that blade boundary layer transition is playing an important role in setting compressor performance. A model which mimics the effects of blade boundary layer transition within the frame work of the average passage model will be presented. Simulations which incorporated this model showed a dramatic improvement in agreement with data.
    Keywords: Aircraft Propulsion and Power
    Type: Design Principles and Methods for Aircraft Gas Turbine Engines; 21-1 - 21-25; RTO-MP-8
    Format: text
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    NASA TECHNICAL REPORTS
  • 8
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    Pratt & Whitney Two Dimensional HSR Nozzle Test in the NASA Lewis 9- By 15- Foot Low Speed Wind Tunnel: Aerodynamic Results (1999)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: This paper discusses a test that was conducted jointly by Pratt & Whitney Aircraft Engines and NASA Lewis Research Center. The test was conducted in NASA's 9- by 15-Foot Low Speed Wind Tunnel (9x15 LSWT). The test setup, methods, and aerodynamic results of this test are discussed. Acoustical results are discussed in a separate paper by J. Bridges and J. Marino.
    Keywords: Aircraft Propulsion and Power
    Type: First NASA/Industry High Speed Research Program Nozzle Symposium; 6-1 - 6-19; NASA/CP-1999-209423
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  • 9
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    Development of Field Measurement Systems for Flight Vehicle Noise (1999)
    In:  CASI
    Details
    Publication Date: 2018-06-05
    Description: Field measurement of noise radiated from flight vehicles is an important element of aircraft noise research programs. At NASA Langley, a dedicated effort that spans over two decades was devoted to the development of acoustic measurement systems to support the NASA noise research programs. The new challenge for vehicle operational noise reduction through varying glide slope and flight path require noise measurement to be made over a very large area under the vehicle flight path. Such a challenge can be met through the digital remote system currently under final development at NASA Langley.
    Keywords: Aircraft Propulsion and Power
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  • 10
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    A Three-Dimensional Linearized Unsteady Euler Analysis for Turbomachinery Blade Rows (1997)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A three-dimensional, linearized, Euler analysis is being developed to provide an efficient unsteady aerodynamic analysis that can be used to predict the aeroelastic and aeroacoustic responses of axial-flow turbo-machinery blading.The field equations and boundary conditions needed to describe nonlinear and linearized inviscid unsteady flows through a blade row operating within a cylindrical annular duct are presented. A numerical model for linearized inviscid unsteady flows, which couples a near-field, implicit, wave-split, finite volume analysis to a far-field eigenanalysis, is also described. The linearized aerodynamic and numerical models have been implemented into a three-dimensional linearized unsteady flow code, called LINFLUX. This code has been applied to selected, benchmark, unsteady, subsonic flows to establish its accuracy and to demonstrate its current capabilities. The unsteady flows considered, have been chosen to allow convenient comparisons between the LINFLUX results and those of well-known, two-dimensional, unsteady flow codes. Detailed numerical results for a helical fan and a three-dimensional version of the 10th Standard Cascade indicate that important progress has been made towards the development of a reliable and useful, three-dimensional, prediction capability that can be used in aeroelastic and aeroacoustic design studies.
    Keywords: Aircraft Propulsion and Power
    Type: NASA-CR-4770 , NAS 1.26:4770 , E-10670
    Format: application/pdf
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