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  • 1
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    Forced Transition Techniques on HSCT Configurations (1999)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: The objectives of this effort were to determine (if possible) the best method: 1) for forcing the boundary layer to transition, 2) for assessing trip effectiveness, 3) for quantifying trip drag, 4) for testing at Reynolds numbers per foot from 5 million to maximum available rather than I to 5 million, and 5) for boundary layer state determination.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: 1997 NASA High-Speed Research Program Aerodynamic Performance Workshop; Volume 1; Part 1; 477-508; NASA/CP-1999-209691/VOL1/PT1
    Format: text
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  • 2
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    High Reynolds Number Effects on HSCT Stability and Control Characteristics (1999)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: Two wind tunnel tests during 1995 in the National Transonic Facility (NTF 070 and 073) served to define Reynolds number effects on longitudinal and lateral-directional stability and control. Testing was completed at both high lift and transonic conditions. The effect of Reynolds number on the total airplane configuration, horizontal and vertical tail effectiveness, forebody chine performance, rudder control and model aeroelastics was investigated. This paper will present pertinent stability and control results from these two test entries. Note that while model aeroelastic effects are examined in this presentation, no corrections for these effects have been made to the data.
    Keywords: Aircraft Stability and Control
    Type: First NASA/Industry High-Speed Research Configuration Aerodynamics Workshop; Part 3; 1253-1284; NASA/CP-1999-209690/PT3
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  • 3
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    Turbulence Model Comparisons and Reynolds Number Effects Over a High-Speed Aircraft at Transonic Speeds (1999)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: This paper gives the results of a grid study, a turbulence model study, and a Reynolds number effect study for transonic flows over a high-speed aircraft using the thin-layer, upwind, Navier-Stokes CFL3D code. The four turbulence models evaluated are the algebraic Baldwin-Lomax model with the Degani-Schiff modifications, the one-equation Baldwin-Barth model, the one-equation Spalart-Allmaras model, and Menter's two-equation Shear-Stress-Transport (SST) model. The flow conditions, which correspond to tests performed in the NASA Langley National Transonic Facility (NTF), are a Mach number of 0.90 and a Reynolds number of 30 million based on chord for a range of angle-of-attacks (1 degree to 10 degrees). For the Reynolds number effect study, Reynolds numbers of 10 and 80 million based on chord were also evaluated. Computed forces and surface pressures compare reasonably well with the experimental data for all four of the turbulence models. The Baldwin-Lomax model with the Degani-Schiff modifications and the one-equation Baldwin-Barth model show the best agreement with experiment overall. The Reynolds number effects are evaluated using the Baldwin-Lomax with the Degani-Schiff modifications and the Baldwin-Barth turbulence models. Five angles-of-attack were evaluated for the Reynolds number effect study at three different Reynolds numbers. More work is needed to determine the ability of CFL3D to accurately predict Reynolds number effects.
    Keywords: Aerodynamics
    Type: First NASA/Industry High-Speed Research Configuration Aerodynamics Workshop; Part 3; 1185-1214; NASA/CP-1999-209690/PT3
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  • 4
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    High Reynolds Number Assessment of Boundary Layer Transition Trip Drag at Mach 2.48 on HSCT Configuration (1999)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: The NASA High Speed Research (HSR) Program is intended to establish a technology base enabling industry development of an economically viable and environmentally acceptable second generation high speed civil transport (HSCT). The HSR program consists of work directed towards several broad technology areas, one of which is aerodynamic performance. The objective of the Configuration Aerodynamics task of the Aerodynamic Performance technology area is the development of aerodynamic drag reduction, stability and control, and propulsion airframe integration technologies required to support the HSCT development process. Towards this goal, computational and empirical based aerodynamic design tools are being developed, evaluated, and validated through ground based experimental testing. In addition, methods for ground to flight scaling are being developed and refined. Successful development of validated design and scaling methodologies will result in improved economy of operation for an HSCT and reduce uncertainty in full-scale flight predictions throughout the development process.
    Keywords: Aerodynamics
    Type: 1998 NASA High-Speed Research Program Aerodynamic Performance Workshop; Volume 1; Part 1; 539-569; NASA/CP-1999-209692/VOL1/PT1
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  • 5
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    Prediction and Assessment of Reynolds Number Sensitivities Associated with Wing Leading-Edge Radius Variations (1999)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: The primary objectives of this study were to expand the data base showing the effects of LE radius distribution and corresponding sensitivity to Rn at subsonic and transonic conditions, and to assess the predictive capability of CFD for these effects. Several key elements led to the initiation of this project: 1) the necessity of meeting multipoint design requirements to enable a viable HSCT, 2) the demonstration that blunt supersonic leading-edges can be associated with performance gain at supersonic speeds , and 3) limited data. A test of a modified Reference H model with the TCA planform and 2 LE radius distributions was performed in the NTF, in addition to Navier-Stokes analysis for an additional 3 LE radius distributions. Results indicate that there is a tremendous potential to improve high-lift performance through the use of a blunt LE across the span given an integrated, fully optimized design, and that low Rn data alone is probably not sufficient to demonstrate the benefit.
    Keywords: Aerodynamics
    Type: 1997 NASA High-Speed Research Program Aerodynamic Performance Workshop; Volume 1; Part 1; 588-611; NASA/CP-1999-209691/VOL1/PT1
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  • 6
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    Boundary Layer Transition in the NTF: HSR Experience and Plans (1999)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: Efforts towards understanding boundary layer transition characteristics on a High Speed Civil Transport (HSCT)-class configuration in the National Transonic Facility (NTF) are ongoing. The majority of the High Speed Research (HSR) data base in the NTF has free transition on the wing, even at low Reynolds numbers (Rn) attainable in conventional facilities. Limited data has been obtained and is described herein showing the effects of a conventional, Braslow method based wing boundary-layer trip on drag. Comparisons are made using force data polars and surface flow visualization at selected angles-of-attack and Mach number. Minimum drag data obtained in this study suggest that boundary layer transition occurred very near the wing leading edge by a chord Rn of 30 million. Sublimating chemicals were used in the air mode of operation only at low Rn and low angles-of-attack with no flap deflections; sublimation results suggest that the forebody and outboard wing panel are the only regions with significant laminar flow. The process and issues related to the sublimating chemical technique as applied in the NTF are discussed. Beyond the existing experience, status of efforts to develop a production transition detection system applicable to both air and cryogenic nitrogen environments is presented.
    Keywords: Aerodynamics
    Type: First NASA/Industry High-Speed Research Configuration Aerodynamics Workshop; Pt. 2; 579-596; NASA/CP-1999-209690/PT2
    Format: text
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  • 7
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    Initial Results of Reynolds Number Testing at LaRC's NTF Using the 2.2% Reference H Model (1999)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: To develop full scale flight performance predictions an understanding of Reynolds number effects on HSCT-class configurations is essential. A wind tunnel database utilizing a 2.2% scale Reference H model in NASA Langley Research Centers National Transonic Facility is being developed to assess these Reynolds number effects. In developing this database temperature and aeroelastic corrections to the wind tunnel data have been identified and are being analyzed. Once final corrections have been developed and applied, then pure Reynolds number effects can be determined. In addition, final corrections will yield the data required for CFD validation at q = 0. Presented in this report are the results of seven tests involving the wing/body configuration. This includes summaries of data acquired in these tests, uncorrected Reynolds number effects, and temperature and aeroelastic corrections. The data presented herein illustrates the successes achieved to date as well as the challenges that will be faced in obtaining full scale flight performance predictions.
    Keywords: Aerodynamics
    Type: First NASA/Industry High-Speed Research Configuration Aerodynamics Workshop; Part 3; 1073-1107; NASA/CP-1999-209690/PT3
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  • 8
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    Aftbody Closure Effects on the Reference H Configuration at Subsonic and Transonic Speeds (1999)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: Experience with afterbody closure effects and accompanying test techniques issues on a High Speed Civil Transport (HSCT)-class configuration is described. An experimental data base has been developed which includes force, moment, and surface pressure data for the High Speed Research (HSR) Reference H configuration with a closed afterbody at subsonic and transonic speeds, and with a cylindrical afterbody at transonic and supersonic speeds. A supporting computational study has been performed using the USM3D unstructured Euler solver for the purposes of computational fluid dynamics (CFD) method assessment and model support system interference assessment with a focus on lower blade mount effects on longitudinal data at transonic speeds. Test technique issues related to a lower blade sting mount strategy are described based on experience in the National Transonic Facility (NTF). The assessment and application of the USM3D code to the afterbody/sting interference problem is discussed. Finally, status and plans to address critical test technique issues and for continuation of the computational study are presented.
    Keywords: Aerodynamics
    Type: First NASA/Industry High-Speed Research Configuration Aerodynamics Workshop; Pt. 2; 529-560; NASA/CP-1999-209690/PT2
    Format: text
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  • 9
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    Forced Transition Techniques on HSCT Configurations (1999)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: This presentation describes the general objectives of the project, followed by background information which led to the initiation of the study, and the approach taken to meet the objectives. Next, experimental studies in the LaRC Unitary Plan Wind Tunnel, the NMA Polysonic Wind Tunnel, and the National Transonic Facility will be discussed. Concluding remarks will close the presentation.
    Keywords: Aircraft Design, Testing and Performance
    Type: 1997 NASA High-Speed Research Program Aerodynamic Performance Workshop; Volume 1; Part 1; 477-508; NASA/CP-1999-209691/VOL1/PT1
    Format: text
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  • 10
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    Prediction and Assessment of Reynolds Number Sensitivities Associated with Wing Leading-Edge Radius Variations (1999)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: The primary objectives of this study were to expand the data base showing the effects of LE radius distribution and corresponding . sensitivity to Rn at subsonic and transonic conditions, and to assess the predictive capability of CFD for these effects. Several key elements led to the initiation of this project: 1) the necessity of meeting multipoint design requirements to enable a viable HSCT, 2) the demonstration that blunt supersonic leading-edges can be associated with performance gain at supersonic speeds , and 3) limited data. A test of a modified Reference H model with the TCA planform and 2 LE radius distributions was performed in the NTF, in addition to Navier-Stokes analysis for an additional 3 LE radius distributions. Results indicate that there is a tremendous potential to improve high-lift performance through the use of a blunt LE across the span given an integrated, fully optimized design, and that low Rn data alone is probably not sufficient to demonstrate the benefit.
    Keywords: Aerodynamics
    Type: 1997 NASA High-Speed Research Program Aerodynamic Performance Workshop; Volume 1; Part 1; 588-610; NASA/CP-1999-209691/VOL1/PT1
    Format: text
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