| 1. |
- Luckrin, J. M., et al.
(författare)
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A synthesis of hybrid RANS/LES CFD results for F-16XL aircraft aerodynamics
- 2015
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Ingår i: 33rd AIAA Applied Aerodynamics Conference. - Reston, Virginia : American Institute of Aeronautics and Astronautics (AIAA). - 9781624103636
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Konferensbidrag (refereegranskat)abstract
- A synthesis is presented of recent numerical predictions for the F-16XL aircraft flow fields and aerodynamics. The computational results were all performed with hybrid RANS/LES formulations, with an emphasis on unsteady flows and subsequent aerodynamics, and results from five computational methods are included. The work was focused on one particular low-speed, high angle-of-attack flight test condition, and comparisons against flight-test data are included. This work represents the third coordinated effort using the F-16XL aircraft, and a unique flight-test data set, to advance our knowledge of slender airframe aerodynamics as well as our capability for predicting these aerodynamics with advanced CFD formulations. The prior efforts were identified as Cranked Arrow Wing Aerodynamics Project International, with the acronyms CAWAPI and CAWAPI-2.
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| 2. |
- Tomac, Maximilian, et al.
(författare)
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Unsteady aero-loads from vortices shed on A320 landing gear door : CFD compared to flight tests
- 2016
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Ingår i: 54th AIAA Aerospace Sciences Meeting. - Reston, Virginia : American Institute of Aeronautics and Astronautics. - 9781624103933
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Konferensbidrag (refereegranskat)abstract
- AFLoNext is a project of four years duration, funded by the European Commission within the Seventh Framework Programme. The project’s main objectives are proving and maturing highly promising flow control and noise reduction technologies for novel aircraft configurations, to achieve a big step forward towards improved aircraft performance and thus reducing the environmental footprint. The project consortium is composed by 40 European partners from 15 countries. One of the six technology streams, which are forming the scientific concept of AFLoNext, is concerned with the mitigation and control of vibrations in the undercarriage area during take-off and landing. Structural components in the vicinity of the landing gears, e.g. undercarriage housing walls, struts or landing gear doors, are often subject to significant dynamic loading. These loads originate from fluctuating aerodynamic pressures and resulting structural vibrations. Unsteady pressures on structural parts are caused by highly fluctuating and complex aerodynamic flow behavior under the fuselage. The paper describes the CFD approach employed to predict such dynamic loads and presents some preliminary results that have been computed with hybrid RANS-LES models and the Lattice Bolzmann method. Several vibration control devices have been proposed and are discussed in the paper. Some of these devices will be installed in the near future on the DLR Airbus 320 ATRA (Advanced Technology Research Aircraft) to perform flight tests to and to measure dynamic loads.
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| 3. |
- Görtz, Stefan, et al.
(författare)
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Standard Unstructured Grid Solutions for Cranked Arrow Wing Aerodynamics Project International F-16XL
- 2009
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Ingår i: Journal of Aircraft. - : American Institute of Aeronautics and Astronautics (AIAA). - 0021-8669 .- 1533-3868. ; 46:2, s. 385-408
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Tidskriftsartikel (refereegranskat)abstract
- Steady and unsteady viscous flow simulations of a full-scale, semispan, and full-span model of the F-16XL-1 aircraft are performed with three different computational fluid dynamics codes using a common unstructured grid. Six different flight conditions are considered. They represent Reynolds and Mach number combinations at subsonic speeds, with and without sideslip. The steady computations of the flow at these flight conditions are made with several Reynolds-averaged Navier-Stokes turbulence models of different complexity. Detached-eddy simulation, delayed detached-eddy simulation, and an algebraic hybrid Reynolds-averaged Navier-Stokes/large-eddy simulation model are used to quantify unsteady effects at the same flight conditions. The computed results are compared with flight-test data in the form of surface pressures, skin friction, and boundary-layer velocity profiles. The focus of the comparison is on turbulence modeling effects and effects of unsteadiness. The overall agreement with flight data is good, with no clear trend as to which physical modeling approach is superior for this class of flow. The Reynolds-averaged Navier-Stokes turbulence models perform well in predicting the flow in an average sense. However, some of the flow conditions involve locally unsteady flow over the aircraft, which are held responsible for the scatter between the different turbulence modeling approaches. The detached-eddy simulations are able to quantify the unsteady effects, although they are not consistently better than the Reynolds-averaged Navier-Stokes turbulence models in predicting the flow in an average sense in these flow regions. Detached-eddy simulation fails to predict boundary-layer profiles consistently over a range of flow regimes, with delayed detached-eddy simulation and hybrid Reynolds-averaged Navier-Stokes/large-eddy simulation models offering a remedy to recover some of the predictive capabilities of the underlying Reynolds-averaged Navier-Stokes turbulence model. Nonetheless, the confidence in the predictive capabilities of the computational fluid dynamics codes with regard to complex vortical flowfields around high-performance aircraft of this planform increased significantly during this study.
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| 4. |
- Luckring, James M., et al.
(författare)
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Synthesis of Hybrid Computational Fluid Dynamics Results for F-16XL Aircraft Aerodynamics
- 2017
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Ingår i: Journal of Aircraft. - 0021-8669 .- 1533-3868. ; 54:6, s. 2100-2114
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Tidskriftsartikel (refereegranskat)abstract
- A synthesis is presented of recent numerical predictions for the F-16XL aircraft flowfields and aerodynamics. The computational analyses were all performed with hybrid Reynolds-averaged Navier-Stokes/large-eddy simulation formulations, with an emphasis on unsteady flows and associated aerodynamics, and results from five computational methods are included. The work focused on one particular low-speed high angle-of-attack flight-test condition, and comparisons against flight-test data are included. This work represents the third coordinated effort using the F-16XL aircraft, and a unique flight-test dataset, to advance the knowledge of slender airframe aerodynamics as well as the capability for predicting these aerodynamics with advanced computational fluid dynamics formulations. The prior efforts were identified as the Cranked-Arrow Wing Aerodynamics Project International.
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| 5. |
- Görtz, Stefan, et al.
(författare)
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Steady and unsteady CFD analysis of the F-16XL using the unstructured edge code
- 2007
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Ingår i: Collection of Technical Papers - 45th AIAA Aerospace Sciences Meeting. - Reston, Virigina : American Institute of Aeronautics and Astronautics. - 1563478900 - 9781563478901 ; , s. 8258-8287
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Konferensbidrag (refereegranskat)abstract
- Steady and unsteady viscous simulations of a full-scale, semi-span and full-span model of the F-16XL-1 aircraft at seven different flight Reynolds/Mach number combinations have been performed with an unstructured CFD code. The steady-state simulations are with several turbulence models of different complexity. Detached-Eddy Simulation (DES) has been used to compute the unsteady flow. The computed results are compared with public domain flight-test data. Very good agreement is demonstrated for surface pressure distribution, local skin friction and boundary velocity profiles. The different turbulence models performed almost equally well, except the Spalart-Allmaras model, which failed to predict the flow qualitatively and quantitatively. The Differential Reynolds Stress Model (DRSM) outperformed all other models when it comes to local span-wise skin friction. DES was superior over RANS modeling at the highest angle of attack, where the flow over the outer wing is separated and partly unsteady.
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| 6. |
- Jirasek, A., et al.
(författare)
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Computational study of the high-lift a-airfoil
- 2001
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Ingår i: Journal of Aircraft. - : American Institute of Aeronautics and Astronautics (AIAA). - 0021-8669 .- 1533-3868. ; 38:4, s. 769-772
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Tidskriftsartikel (refereegranskat)
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| 7. |
- Rizzi, Arthur, et al.
(författare)
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Aeroelastic analysis of the CAWAPI F-16XL configuration at transonic speeds
- 2014
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Ingår i: 52nd AIAA Aerospace Sciences Meeting - AIAA Science and Technology Forum and Exposition, SciTech 2014.
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Konferensbidrag (refereegranskat)abstract
- This article present an aeroelastic study of CAWAPI F-16XL aircraft. The structural model for this aircraft is publicly available and is therefore replaced by a structural model estimate which is constructed based on data available in public literature. The aeroelastic solution is done using inviscid solution for two flight conditions - FC70 and FC79. The primary task is to assess importance of the aeroelastic effects on the solution and to asses weather large discrepancies observed at flight condition FC70 between the computational and experimental data.
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| 8. |
- Rizzi, Arthur, et al.
(författare)
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Hybrid RANS-LES simulations of F-16XL aircraft in low-speed high-alpha flight
- 2015
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Ingår i: 33rd AIAA Applied Aerodynamics Conference. - Reston, Virginia : American Institute of Aeronautics and Astronautics. - 9781624103636
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Konferensbidrag (refereegranskat)abstract
- This article presents the comparisons of the results of the CFD study around the F-16XL CAWAPI configuration for flight condition FC25: M∞ = 0:24, α = 19:8°, β = 0°, Re = 32:2M. Previous work has established this case of high angle of attack flight as an outlier in the sense that the computed pressure distributions compared less favorably with those measured in flight tests than did similar comparisons for cases at lower angle of attack. One reason suggested for the discrepancy was that the flow over the outer wing panel was unsteady, possibly including vortex breakdown. This paper presents results computed time accurately with physical modeling that can capture such unsteady flow phenomena. The physical modeling employed is an innovative hybrid RANS-LES model termed HYB0. The simulations obtained are compared with those measured during flight testing of the vehicle as well as with results computed with RANS and URANS physical modeling. Although differences are found among all the results compared, they are not exceeding large. Further analysis of the results are presented, and conclusions are drawn.
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| 9. |
- Rizzi, Arthur, et al.
(författare)
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What was learned from numerical simulations of F-16XL (CAWAPI) at flight conditions
- 2007
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Ingår i: Collection of Technical Papers - 45th AIAA Aerospace Sciences Meeting. - Reston, Virigina : American Institute of Aeronautics and Astronautics. - 1563478900 - 9781563478901 ; , s. 8385-8420
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Konferensbidrag (refereegranskat)abstract
- Ten groups participating in the CAWAPI project have contributed steady and unsteady viscous simulations of a full-scale, semi-span model of the F-16XL-I aircraft at three different categories of flight Reynolds/Mach number combinations for comparison with flight-test measurements for purposes of code validation and improved understanding of the flight physics of complex interacting vortical flows. The steady-state simulations are done with several turbulence models of different complexity with no topology information required and which overcome Boussinesq-assumption problems in vortical flows. Detached-Eddy Simulation (DES) has been used to compute the unsteady flow. Common structured and unstructured grids as well as individually-adapted unstructured grids have been used. Although discrepancies are observed in the comparisons, overall reasonable agreement is demonstrated for surface pressure distribution, local skin friction and boundary velocity profiles. The physical modeling, steady or unsteady, and the grid resolution both contribute to the discrepancies observed in the comparisons with flight data, but at this time it cannot be determined how much each part contributes to the whole. Overall it can be said that the technology readiness of CFD-simulation technology for the study of vehicle performance of e.g. the F-16XL has matured since 2001 such that it can be used today with a reasonable level of confidence in practical use.
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| 10. |
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