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  • 1
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    On a finite element CFD algorithm for compressible, viscous and turbulent aerodynamic flows (1987)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: This paper develops and analyses individual construction aspects of an efficient and accurate finite element algorithm for prediction of viscous and turbulent flow fields of impact in aerodynamics. The theoretical construction employs a Taylor weak statement (TWS) for coincident embedding of stability mechanisms within a classic Galerkin finite element formulation of semidiscrete approximation error orthogonalization. A wide variety of the stabilizing mechanisms of independently derived CFD algorithms are contained within the TWS theory. An implicit construction that meets the requirement of efficient convergence to steady state is developed. The theoretical asymptotic error estimates of the TWS finite element algorithm for supersonic and viscous boundary layer flows are verified. Application to a three-dimensional turbulent flow is cited.
    Keywords: AERODYNAMICS
    Type: International Journal for Numerical Methods in Fluids (ISSN 0271-2091); 7; 1235-125
    Format: text
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  • 2
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    Navier-Stokes computations of projectile base flow with and without mass injection (1985)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: AIAA Journal (ISSN 0001-1452); 23; 1348-135
    Format: text
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  • 3
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    Chemical nonequilibrium effects on flowfields for aeroassisted orbital transfer vehicles (1985)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: Journal of Spacecraft and Rockets (ISSN 0022-4650); 22; 54-59
    Format: text
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  • 4
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    Flow diagnostics and visualization in wind tunnels and flight (1986)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The Langley Research Center has a concentrated and directed effort under way to develop both conventional and non-intrusive diagnostic instrumentation. These instruments are being developed to operate over large Mach number, total temperature, and total pressure ranges. Efforts are being made to evaluate the measurements made by the various instruments to determine the most accurate and reliable instrument to be used under a given flow environment. Although only one flow visualization technique was described, there are many different types presently being used at Langley Research Center.
    Keywords: AERODYNAMICS
    Type: Langley Symposium on Aerodynamics, Volume 1; p 279-310
    Format: application/pdf
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  • 5
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    Calculation of helicopter airfoil characteristics for high tip-speed applications (1986)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: In this paper, we have applied a new aerodynamic tool to the study of helicopter airfoil characteristics. We have shown that the computed airloads reproduce completely the experimental behavior of representative airfoils across the transonic regime. In addition, the computational details of the flow fields, the surface pressure distributions, and the viscous-layer characteristics enable us to trace the evolution of the physical changes that occur as m infinity or Re increases. Descriptions of the complicated development of shock waves, shock-induced separation supplement the information that has been obtained heretofore in wind tunnels. In validating our calculations and assessing the accuracy of the results, including extensive grid-refinement studies and comparisons with data from numerous wind tunnels, we have defined the capabilities and limitations of the code ARC2D more precisely. This important aspect of the investigations can complement wind-tunnel tests, by providing flow-field details that are difficult to measure and by extending the range of low parameters beyond the capabilities of existing wind tunnels. The code has now progressed from a purely research stage to almost a production stage, where it can be run by specialists in the helicopter industry.
    Keywords: AERODYNAMICS
    Type: American Helicopter Society, Journal (ISSN 0002-8711); 31; 3-9
    Format: text
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  • 6
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    Measurements of the unsteady flow field within the stator row of a transonic axial-flow fan. Part 2: Results and discussion (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Unsteady velocity field measurements made within the stator row of a transonic axial-flow fan are presented. Measurements were obtained at midspan for two different stator blade rows using a laser anemometer. The first stator row consists of double circular-arc airfoils with a solidity of 1.68. The second features controlled-diffusion airfoils with a solidity of 0.85. Both were tested at design-speed peak efficiency conditions. In addition, the controlled-diffusion stator was also tested at near stall conditions. The procedures developed here are used to identify the rotor wake generated and unresolved unsteadiness from the velocity measurements (rotor wake generated unsteadiness refers to the unsteadiness generated by the rotor wake velocity deficit and unresolved unsteadiness refers to all remaining unsteadiness which contributes to the spread in the distribution of velocities such as vortex shedding, turbulence, etc.). Auto and cross correlations of these unsteady velocity fluctuations are presented to show their relative magnitude and spatial distributions. Amplification and attenuation of both rotor wake generated and unresolved unsteadiness are shown to occur within the stator blade passage.
    Keywords: AERODYNAMICS
    Type: NASA-TM-88946 , E-3394 , NAS 1.15:88946 , USAAVSCOM-TR-86-C-31
    Format: application/pdf
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  • 7
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    Addressing the hypersonic simulation problem (1986)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The hypersonic simulation problem is solved by the meshing of bench-marked experimental data with results from validated computational fluid dynamic codes. The example presented is for the reentry of the Space Shuttle Orbiter. Mach number effects were assessed by parametrically varying free-stream Mach number and angle of attack in a series of inviscid, perfect-gas computations carried out on a modified Orbiter geometry. Real-gas effects were determined by making calculations at specific points of the reentry trajectory using equilibrium air thermodynamics and comparing with corresponding perfect-gas computations. Viscous computations were also made for both the basic Orbiter body and control surfaces. A methodology is developed that permits the extrapolation of wind tunnel data to flight situations, providing a solution to the hypersonic simulation problem.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 86-9775
    Format: text
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  • 8
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    Measurements of the unsteady flow field within the stator row of a transonic axial-flow fan. 1: Measurement and analysis technique (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: This two-part paper presents laser anemometer measurements of the unsteady velocity field within the stator row of a transonic axial-flow fan. The objective is to provide additional insight into unsteady blade-row interactions within high speed compressors which affect stage efficiency, energy transfer, and other design considerations. Part 1 describes the measurement and analysis techniques used for resolving the unsteady flow field features. The ensemble-average and variance of the measured velocities are used to identify the rotor wake generated and unresolved unsteadiness, respectively. (Rotor wake generated unsteadiness refers to the unsteadiness generated by the rotor wake velocity deficit and the term unresolved unsteadiness refers to all remaining contributions to unsteadiness such as vortex shedding, turbulence, mass flow fluctuations, etc.). A procedure for calculating auto and cross correlations of the rotor wake generated and unresolved unsteady velocity fluctuations is described. These unsteady-velocity correlations have significance since they also result from a decomposition of the Navier-Stokes equations. This decomposition of the Navier-Stokes equations resulting in the velocity correlations used to describe the unsteady velocity field will also be outlined in this paper.
    Keywords: AERODYNAMICS
    Type: NASA-TM-88945 , E-3393 , NAS 1.15:88945 , USAAVSCOM-TR-86-C-30
    Format: application/pdf
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  • 9
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    Measurements of the unsteady flow field within the stator row of a transonic axial-flow fan. II - Results and discussion (1987)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Unsteady velocity field measurements made within the stator row of a transonic axial-flow fan are presented. Measurements were obtained at midspan for two different stator blade rows using a laser anemometer. The first stator row consists of double circular-arc airfoils with a solidity of 1.68. The second features controlled-diffusion airfoils with a solidity of 0.85. Both were tested at design-speed peak efficiency conditions. In addition, the controlled-diffusion stator was also tested at near stall conditions. The procedures developed here are used to identify the rotor wake generated and unresolved unsteadiness from the velocity measurements (rotor wake generated unsteadiness refers to the unsteadiness generated by the rotor wake velocity deficit and unresolved unsteadiness refers to all remaining unsteadiness which contributes to the spread in the distribution of velocities such as vortex shedding, turbulence, etc.). Auto and cross correlations of these unsteady velocity fluctuations are presented to show their relative magnitude and spatial distributions. Amplification and attenuation of both rotor wake generated and unresolved unsteadiness are shown to occur within the stator blade passage.
    Keywords: AERODYNAMICS
    Type: ASME PAPER 87-GT-227
    Format: text
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  • 10
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    Measurements of the unsteady flow field within the stator row of a transonic axial-flow fan. I - Measurement and analysis technique (1987)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: This two-part paper presents laser anemometer measurements of the unsteady velocity field within the stator row of a transonic axial-flow fan. The objective is to provide additional insight into unsteady blade-row interactions within highspeed compressors which affect stage efficiency, energy transfer, and other design considerations. Part 1 describes the measurement and analysis techniques used for resolving the unsteady flow field features. The ensemble-average and variance of the measured velocities are used to identify the rotor wake generated and unresolved unsteadiness, respectively. (Rotor wake generated unsteadiness refers to the unsteadiness generated by the rotor wake velocity deficit and the term unresolved unsteadiness refers to all remaining contributions to unsteadiness such as vortex shedding, turbulence, mass flow fluctutions, etc.). A procedure for calculating auto and cross correlations of the rotor wake generated and unresolved unsteady velocity fluctuations is described. These unsteady-velocity correlations have significance since they also result from a decomposition of the Navier-Stokes equations. This decomposition of the Navier-Stokes equations resulting in the velocity correlations used to describe the unsteady velocity field will also be outlined in this paper.
    Keywords: AERODYNAMICS
    Type: ASME PAPER 87-GT-226
    Format: text
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