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  • 11
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    F-16XL Hybrid Reynolds-Averaged NavierStokes/Large Eddy Simulation on Unstructured Grids (2017)
    In:  CASI
    Details
    Publication Date: 2019-06-13
    Description: The Cranked-Arrow Wing Aerodynamics Project International investigation is continued with the FUN3D and USM3D flow solvers to fuse flight test, wind-tunnel test, and simulation of swept-wing aerodynamic features. Simulations of a low-speed, high-angle-of-attack condition are compared: detached-eddy simulation, modified delayed detached-eddy simulation, and the SpalartAllmaras Reynolds-averaged NavierStokes model. Isosurfaces of Q criterion show the development of coherent primary and secondary vortices on the upper surface of the wing that spiral, burst, and commingle. Mean detached-eddy simulation and modified delayed detached-eddy simulation pressures better predict the flight-test measurements than SpalartAllmaras model predictions, especially on the outer-wing section. The USM3D simulations predicted many sharp tones in volume point pressure spectra with low broadband noise, and the FUN3D simulations predicted more broadband noise with weaker tones. Spectra of the volume points near the outer-wing leading edge were primarily broadband for both codes. Time-averaged forces are very similar between FUN3D simulations and between USM3D simulations, but FUN3D predicts slightly higher lift and lower drag than USM3D. There is more variation in the pitching moment predictions. Spectra of the unsteady forces and moment are mostly broadband for FUN3D and tonal for USM3D simulations.
    Keywords: Aerodynamics
    Type: NF1676L-30239 , Journal of Aircraft (ISSN 0021-8669) (e-ISSN 1533-3868); 54; 6; 2027-2049
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 12
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    Experimental Sonic Boom Measurements on a Mach 1.6 Cruise Low-Boom Configuration (2012)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: A wind tunnel test has been conducted by Gulfstream Aerospace Corporation (GAC) to measure the sonic boom pressure signature of a low boom Mach 1.6 cruise business jet in the Langley Unitary Plan Wind Tunnel at Mach numbers 1.60 and 1.80. Through a cooperative agreement between GAC and the National Aeronautics and Space Administration (NASA), GAC provided NASA access to some of the experimental data and NASA is publishing these data for the sonic boom research community. On-track and off-track near field sonic boom pressure signatures were acquired at three separation distances (0.5, 1.2, and 1.7 reference body lengths) and three angles of attack (-0.26deg, 0.26deg, and 0.68deg). The model was blade mounted to minimize the sting effects on the sonic boom signatures. Although no extensive data analysis is provided, selected data are plotted to illustrate salient features of the data. All of the experimental sonic boom pressure data are tabulated. Schlieren images of the configuration are also included.
    Keywords: Aerodynamics
    Type: NASA/TM-2012-217598 , L-20103 , NF1676L-13939
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 13
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    Active Aircraft Pylon Noise Control System (2015)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: An active pylon noise control system for an aircraft includes a pylon structure connecting an engine system with an airframe surface of the aircraft and having at least one aperture to supply a gas or fluid therethrough, an intake portion attached to the pylon structure to intake a gas or fluid, a regulator connected with the intake portion via a plurality of pipes, to regulate a pressure of the gas or fluid, a plenum chamber formed within the pylon structure and connected with the regulator, and configured to receive the gas or fluid as regulated by the regulator, and a plurality of injectors in communication with the plenum chamber to actively inject the gas or fluid through the plurality of apertures of the pylon structure.
    Keywords: Aircraft Design, Testing and Performance; Acoustics
    Format: application/pdf
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  • 14
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    Computational and Experimental Flow Field Analyses of Separate Flow Chevron Nozzles and Pylon Interaction (2003)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A computational and experimental flow field analyses of separate flow chevron nozzles is presented. The goal of this study is to identify important flow physics and modeling issues required to provide highly accurate flow field data which will later serve as input to the Jet3D acoustic prediction code. Four configurations are considered: a baseline round nozzle with and without a pylon, and a chevron core nozzle with and without a pylon. The flow is simulated by solving the asymptotically steady, compressible, Reynolds-averaged Navier-Stokes equations using an implicit, up-wind, flux-difference splitting finite volume scheme and standard two-equation kappa-epsilon turbulence model with a linear stress representation and the addition of a eddy viscosity dependence on total temperature gradient normalized by local turbulence length scale. The current CFD results are seen to be in excellent agreement with Jet Noise Lab data and show great improvement over previous computations which did not compensate for enhanced mixing due to high temperature gradients.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: AIAA Paper 2003-3212 , 9th AIAA/CEAS Aeroacoustics Conference and Exhibition; May 12, 2003 - May 14, 2003; Hilton Head, SC; United States
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  • 15
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    Computational Analysis of the Flow and Acoustic Effects of Jet-Pylon Interaction (2005)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Computational simulation and prediction tools were used to understand the jet-pylon interaction effect in a set of bypass-ratio five core/fan nozzles. Results suggest that the pylon acts as a large scale mixing vane that perturbs the jet flow and jump starts the jet mixing process. The enhanced mixing and associated secondary flows from the pylon result in a net increase of noise in the first 10 diameters of the jet s development, but there is a sustained reduction in noise from that point downstream. This is likely the reason the pylon nozzle is quieter overall than the baseline round nozzle in this case. The present work suggests that focused pylon design could lead to advanced pylon shapes and nozzle configurations that take advantage of propulsion-airframe integration to provide additional noise reduction capabilities.
    Keywords: Acoustics
    Type: AIAA Paper 2005-3083 , 11th AIAA/CEAS Aeroacoustics Conference; May 23, 2005 - May 25, 2005; Monterey, CA; United States
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  • 16
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    Preliminary Computational Study for Future Tests in the NASA Ames 9 foot' x 7 foot Wind Tunnel (2016)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The NASA Advanced Air Vehicles Program, Commercial Supersonics Technology Project seeks to advance tools and techniques to make over-land supersonic flight feasible. In this study, preliminary computational results are presented for future tests in the NASA Ames 9 foot x 7 foot supersonic wind tunnel to be conducted in early 2016. Shock-plume interactions and their effect on pressure signature are examined for six model geometries. Near- field pressure signatures are assessed using the CFD code USM3D to model the proposed test geometries in free-air. Additionally, results obtained using the commercial grid generation software Pointwise Reigistered Trademark are compared to results using VGRID, the NASA Langley Research Center in-house mesh generation program.
    Keywords: Aerodynamics
    Type: NF1676L-21734 , AIAA Aerospace Sciences Meeting; Jan 04, 2016 - Jan 08, 2016; San Diego, CA; United States
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    NASA TECHNICAL REPORTS
  • 17
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    Active Aircraft Pylon Noise Control System (2017)
    In:  CASI
    Details
    Publication Date: 2019-08-27
    Description: An active pylon noise control system for an aircraft includes a pylon structure connecting an engine system with an airframe surface of the aircraft and having at least one aperture to supply a gas or fluid therethrough, an intake portion attached to the pylon structure to intake a gas or fluid, a regulator connected with the intake portion via a plurality of pipes, to regulate a pressure of the gas or fluid, a plenum chamber formed within the pylon structure and connected with the regulator, and configured to receive the gas or fluid as regulated by the regulator, and a plurality of injectors in communication with the plenum chamber to actively inject the gas or fluid through the plurality of apertures of the pylon structure.
    Keywords: Acoustics; Aircraft Design, Testing and Performance
    Format: application/pdf
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  • 18
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    Computational and Experimental Study of Supersonic Nozzle Flow and Aft-Deck Interactions (2016)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: NASA has been conducting research into reducing sonic boom and changing FAA regulations to allow for supersonic commercial transport over land in the United States. This particular study looks at a plume passing through a shock generated from an aft deck on a nacelle; the aft deck is meant to represent the trailing edge of a wing. NASA Langley Research Center USM3D CFD code results are compared to the experimental data taken at the NASA Glenn Research Center 1-foot by 1-foot Supersonic Wind Tunnel. This study included examining two turbulence models along with different volume sourcing methods for grid generation. The results show that using the k-epsilon turbulence model within USM3D produced shock signatures that closely follow the experimental data at a variety of nozzle pressure ratio settings.
    Keywords: Aerodynamics; Fluid Mechanics and Thermodynamics
    Type: NF1676L-21552 , AIAA Aerospace Sciences Meeting; Jan 04, 2016 - Jan 08, 2016; San Diego, CA; United States
    Format: application/pdf
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  • 19
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    USM3D Predictions of Supersonic Nozzle Flow (2014)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: This study focused on the NASA Tetrahedral Unstructured Software System CFD code (USM3D) capability to predict supersonic plume flow. Previous studies, published in 2004 and 2009, investigated USM3D's results versus historical experimental data. This current study continued that comparison however focusing on the use of the volume souring to capture the shear layers and internal shock structure of the plume. This study was conducted using two benchmark axisymmetric supersonic jet experimental data sets. The study showed that with the use of volume sourcing, USM3D was able to capture and model a jet plume's shear layer and internal shock structure.
    Keywords: Fluid Mechanics and Thermodynamics; Aerodynamics
    Type: AIAA Paper 2014-2270 , NF1676L-18893 , AIAA Applied Aerodynamics Conference; Jun 16, 2014 - Jun 20, 2014; Atlanta, GA; United States|AIAA Aviation and Aeronautics Forum and Exposition (AVIATION 2014); Jun 16, 2014 - Jun 20, 2014; Atlanta, GA; United States
    Format: application/pdf
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  • 20
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    Numerical Investigation of a Fuselage Boundary Layer Ingestion Propulsion Concept (2013)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: In the present study, a numerical assessment of the performance of fuselage boundary layer ingestion (BLI) propulsion techniques was conducted. This study is an initial investigation into coupling the aerodynamics of the fuselage with a BLI propulsion system to determine if there is sufficient potential to warrant further investigation of this concept. Numerical simulations of flow around baseline, Boundary Layer Controlled (BLC), and propelled boundary layer controlled airships were performed. Computed results showed good agreement with wind tunnel data and previous numerical studies. Numerical simulations and sensitivity analysis were then conducted on four BLI configurations. The two design variables selected for the parametric study of the new configurations were the inlet area and the inlet to exit area ratio. Current results show that BLI propulsors may offer power savings of up to 85% over the baseline configuration. These interim results include the simplifying assumption that inlet ram drag is negligible and therefore likely overstate the reduction in power. It has been found that inlet ram drag is not negligible and should be included in future analysis.
    Keywords: Aerodynamics
    Type: AIAA Paper 2013-4402 , NF1676L-17000 , AIAA Aviation Technology, Integration, and Operations (ATIO) Conference; Aug 12, 2013 - Aug 14, 2013; Los Angeles, CA; United States
    Format: application/pdf
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