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  • 1
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    Experimental and Computational Investigation of Multiple Injection Ports in a Convergent-Divergent Nozzle for Fluidic Thrust Vectoring (2003)
    In:  CASI
    Details
    Publication Date: 2019-07-27
    Description: A computational and experimental study was conducted to investigate the effects of multiple injection ports in a two-dimensional, convergent-divergent nozzle, for fluidic thrust vectoring. The concept of multiple injection ports was conceived to enhance the thrust vectoring capability of a convergent-divergent nozzle over that of a single injection port without increasing the secondary mass flow rate requirements. The experimental study was conducted at static conditions in the Jet Exit Test Facility of the 16-Foot Transonic Tunnel Complex at NASA Langley Research Center. Internal nozzle performance was obtained at nozzle pressure ratios up to 10 with secondary nozzle pressure ratios up to 1 for five configurations. The computational study was conducted using the Reynolds Averaged Navier-Stokes computational fluid dynamics code PAB3D with two-equation turbulence closure and linear Reynolds stress modeling. Internal nozzle performance was predicted for nozzle pressure ratios up to 10 with a secondary nozzle pressure ratio of 0.7 for two configurations. Results from the experimental study indicate a benefit to multiple injection ports in a convergent-divergent nozzle. In general, increasing the number of injection ports from one to two increased the pitch thrust vectoring capability without any thrust performance penalties at nozzle pressure ratios less than 4 with high secondary pressure ratios. Results from the computational study are in excellent agreement with experimental results and validates PAB3D as a tool for predicting internal nozzle performance of a two dimensional, convergent-divergent nozzle with multiple injection ports.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: AIAA Paper 2003-3802 , 21st AIAA Applied Aerodynamics Conference; 23-26 Jun. 20003; Orlando, FL; United States
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  • 2
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    Experimental and Computational Investigation of Multiple Injection Ports in a Convergent-Divergent Nozzle for Fluidic Thrust Vectoring (2003)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A computational and experimental study was conducted to investigate the effects of multiple injection ports in a two-dimensional, convergent-divergent nozzle, for fluidic thrust vectoring. The concept of multiple injection ports was conceived to enhance the thrust vectoring capability of a convergent-divergent nozzle over that of a single injection port without increasing the secondary mass flow rate requirements. The experimental study was conducted at static conditions in the Jet Exit Test Facility of the 16-Foot Transonic Tunnel Complex at NASA Langley Research Center. Internal nozzle performance was obtained at nozzle pressure ratios up to 10 with secondary nozzle pressure ratios up to 1 for five configurations. The computational study was conducted using the Reynolds Averaged Navier-Stokes computational fluid dynamics code PAB3D with two-equation turbulence closure and linear Reynolds stress modeling. Internal nozzle performance was predicted for nozzle pressure ratios up to 10 with a secondary nozzle pressure ratio of 0.7 for two configurations. Results from the experimental study indicate a benefit to multiple injection ports in a convergent-divergent nozzle. In general, increasing the number of injection ports from one to two increased the pitch thrust vectoring capability without any thrust performance penalties at nozzle pressure ratios less than 4 with high secondary pressure ratios. Results from the computational study are in excellent agreement with experimental results and validates PAB3D as a tool for predicting internal nozzle performance of a two dimensional, convergent-divergent nozzle with multiple injection ports.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: AIAA Paper 2003-3802 , 21st AIAA Applied Aerodynamics Conference; Jun 23, 2003 - Jun 26, 2003; Orlando, FL; United States
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  • 3
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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
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  • 4
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    Source Term Model for an Array of Vortex Generator Vanes (2003)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: A source term model was developed for numerical simulations of an array of vortex generators. The source term models the side force created by a vortex generator being modeled. The model is obtained by introducing a side force to the momentum and energy equations that can adjust its strength automatically based on a local flow. The model was tested and calibrated by comparing data from numerical simulations and experiments of a single low-profile vortex generator vane, which is only a fraction of the boundary layer thickness, over a flat plate. The source term model allowed a grid reduction of about seventy percent when compared with the numerical simulations performed on a fully gridded vortex generator without adversely affecting the development and capture of the vortex created. The source term model was able to predict the shape and size of the stream wise vorticity and velocity contours very well when compared with both numerical simulations and experimental data.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NASA/CR-2003-212157 , NAS 1.26:212157
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  • 5
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    Source Term Model for Vortex Generator Vanes in a Navier-Stokes Computer Code (2004)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A source term model for an array of vortex generators was implemented into a non-proprietary Navier-Stokes computer code, OVERFLOW. The source term models the side force created by a vortex generator vane. The model is obtained by introducing a side force to the momentum and energy equations that can adjust its strength automatically based on the local flow. The model was tested and calibrated by comparing data from numerical simulations and experiments of a single low profile vortex generator vane on a flat plate. In addition, the model was compared to experimental data of an S-duct with 22 co-rotating, low profile vortex generators. The source term model allowed a grid reduction of about seventy percent when compared with the numerical simulations performed on a fully gridded vortex generator on a flat plate without adversely affecting the development and capture of the vortex created. The source term model was able to predict the shape and size of the stream-wise vorticity and velocity contours very well when compared with both numerical simulations and experimental data. The peak vorticity and its location were also predicted very well when compared to numerical simulations and experimental data. The circulation predicted by the source term model matches the prediction of the numerical simulation. The source term model predicted the engine fan face distortion and total pressure recovery of the S-duct with 22 co-rotating vortex generators very well. The source term model allows a researcher to quickly investigate different locations of individual or a row of vortex generators. The researcher is able to conduct a preliminary investigation with minimal grid generation and computational time.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: AIAA Paper 2004-1236 , 42nd AIAA Aerospace Sciences Meeting and Exhibit; Jan 05, 2004 - Jan 08, 2004; Reno, NV; United States
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  • 6
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    Source Term Model for Steady Micro Jets in a Navier-Stokes Computer Code (2005)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A source term model for steady micro jets was implemented into a non-proprietary Navier-Stokes computer code, OVERFLOW. The source term models the mass flow and momentum created by a steady blowing micro jet. The model is obtained by adding the momentum and mass flow created by the jet to the Navier-Stokes equations. The model was tested by comparing with data from numerical simulations of a single, steady micro jet on a flat plate in two and three dimensions. The source term model predicted the velocity distribution well compared to the two-dimensional plate using a steady mass flow boundary condition, which was used to simulate a steady micro jet. The model was also compared to two three-dimensional flat plate cases using a steady mass flow boundary condition to simulate a steady micro jet. The three-dimensional comparison included a case with a grid generated to capture the circular shape of the jet and a case without a grid generated for the micro jet. The case without the jet grid mimics the application of the source term. The source term model compared well with both of the three-dimensional cases. Comparisons of velocity distribution were made before and after the jet and Mach and vorticity contours were examined. The source term model allows a researcher to quickly investigate different locations of individual or several steady micro jets. The researcher is able to conduct a preliminary investigation with minimal grid generation and computational time.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: AIAA Paper 2005-1401 , 43rd AIAA Aerospace Sciences Meeting and Exhibit; Jan 10, 2005 - Jan 13, 2005; Reno, NV; United States
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  • 7
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    Efficient Unstructured Grid Adaptation Methods for Sonic Boom Prediction (2008)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: This paper examines the use of two grid adaptation methods to improve the accuracy of the near-to-mid field pressure signature prediction of supersonic aircraft computed using the USM3D unstructured grid flow solver. The first method (ADV) is an interactive adaptation process that uses grid movement rather than enrichment to more accurately resolve the expansion and compression waves. The second method (SSGRID) uses an a priori adaptation approach to stretch and shear the original unstructured grid to align the grid with the pressure waves and reduce the cell count required to achieve an accurate signature prediction at a given distance from the vehicle. Both methods initially create negative volume cells that are repaired in a module in the ADV code. While both approaches provide significant improvements in the near field signature (〈 3 body lengths) relative to a baseline grid without increasing the number of grid points, only the SSGRID approach allows the details of the signature to be accurately computed at mid-field distances (3-10 body lengths) for direct use with mid-field-to-ground boom propagation codes.
    Keywords: Acoustics
    Type: AIAA-2008-7327 , 26th AIAA Applied Aerodynamics Conference; Aug 18, 2008 - Aug 21, 2008; Honolulu, HI; United States
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  • 8
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    Preliminary Results from the QuietSpike Flight Test (2007)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: This viewgraph presentation reviews the QuietSpike flight test results. It shows the previous tests from Nearfield probes. The presentation then reviews the approach to test the QuietSpike, and shows graphics of the positions of the test vehicles. It also shows the components of the Sonic Boom Probing Noseboom. A graph of the Pressure Over- Under-shoot (Shaped Sonic Boom Demonstration (SSBD)Data) is presented. It reviews the Shock Probing Orientations, explaining that the probing plane is always behind the tail of the QuietSpike jet. Graphs of the Shock Position Geometry (SSBD Data) and the QuietSpike signature as of the test on 12/13/06, Near-Field Probing Directly Under the QuietSpike jet, and Near-Field Probing to Side, Near-Field Probing Above and to Side. Several slides review the Computational Fluid Dynamic models, and results compared to the probe tests.
    Keywords: Aircraft Design, Testing and Performance
    Type: Industry Panel Presentation at the University of Southern California; Nov 03, 2017; Los Angeles, CA; United States|Fundamental Aeronautics Program 1st Annual Meeting; Oct 30, 2007 - Nov 01, 2007; New Orleans, LA; United States
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