USM3D Simulations for the F-16XL Aircraft Configuration

Elmiligui, Alaa A.; Abdol-Hamid, Khaled S.; Cavallo, Peter A.; Parlette, Edward B.

doi:10.2514/1.c033242

Cited by 4 publications

(5 citation statements)

References 22 publications

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“…Elmiligui et al's [53] findings demonstrated that difficulties remain for resolving separated vortex flows at differing scales with well-established turbulence models. The secondary vortex difficulties could relate to emergent shear-layer separation flow physics as is discussed below in the diamond wing studies.…”

Section: Rans Simulationmentioning

confidence: 99%

“…One contribution from CAWAPI-2 was the due diligence that Elmiligui et al [53] applied in obtaining their solution shown in Fig. 14 for FC-25.…”

Section: Slender Delta Wing Aircraftmentioning

confidence: 99%

“…14 for FC-25. Secondary vortices form from smooth-surface separation, and through a combination of four levels of grid resolution and turbulence model assessments, Elmiligui et al [53] achieved improved secondary vortex resolution with correspondingly improved correlations with the flight test data. In this case, the improved predictions came from the turbulence model, while the Spalart-Allmaras (SA) model yielded no secondary vortex even after substantial grid refinement.…”

Section: Slender Delta Wing Aircraftmentioning

confidence: 99%

“…

Figure 14. Secondary vortex predictions by RANS, CAWAPI-2. FC-25: Elmiligui et al [53]. (a) Vortex visualisation, and (b) chordwise pressure predictions, four different grid resolutions and flight data. …”

Section: Slender Delta Wing Aircraftmentioning

confidence: 99%

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Separated and vortical flow in aircraft aerodynamics: a CFD perspective

Rizzi

2023

Aeronaut. j.

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In the early era of aviation, Frederick Lanchester was both an inventor and a theoretician driven by the need for a theory of flight that would reduce the guesswork in designing new aircraft. His book Aerodynamics in 1907 laid down the early foundations of such a theory. The theory with contributions from others, notably Ludwig Prandtl, was refined to become the basis for the sleek designs of WWII aircraft brought about with little guesswork. New technology changed aircraft design radically with the increased speed of jet propulsion reaching into the transonic range with nonlinear aerodynamics. In the late 1940s and early 1950s substantial guesswork returned to aircraft design. The legacy of Lanchester et al., however, lived on with the development of computational fluid dynamics (CFD) that could guide designers through nonlinear transonic effects. This article presents a historical sketch of how CFD developed, illustrated with examples explaining some of the difficulties overcome in the design of the first-generation swept-wing transonic fighters. The historical study is forensic CFD in search for the likely explanation of the designer’s choice for the wing shape that went into production a long time ago. The capability of current CFD applied to the aerodynamics of aircraft with slender wings is surveyed. The cases discussed involve flow patterns with coherent vortices over hybrid wings and wings of moderate sweep. Vortex-flow aerodynamics pertains to understanding the interaction of concentrated vortices with aircraft components. Modern Reynolds-Averaged Navier-Stokes (RANS) technology is useful to predict attached flow. But vortex interaction with other vortices and breakdown lead to unsteady, largely separated flow which has been found out of scope for RANS. Direct simulation of the Navier-Stokes equations is out of computational reach in the foreseeable future, and the need for better physical modeling is evident. Both cruise performance and stalling characteristics are influenced by strong interactions. Two important aspects of wing-flow physics are discussed: separation from a smooth surface that creates a vortex, and vortex bursting, the abrupt breakdown of a vortex with a subsequent loss of lift. Vortex aerodynamics of not-so-slender wings encounter particularly challenging problems, and it is shown how the design of early-generation operational aircraft surmounted these difficulties. Through use of forensic CFD, the article concludes with two case studies of aerodynamic design: how the Saab J29A wing maintains control authority near stall, and how the Saab J32 mitigates pitch-up instability at high incidence.

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Section: Rans Simulationmentioning

confidence: 99%

“…One contribution from CAWAPI-2 was the due diligence that Elmiligui et al [53] applied in obtaining their solution shown in Fig. 14 for FC-25.…”

Section: Slender Delta Wing Aircraftmentioning

confidence: 99%

Section: Slender Delta Wing Aircraftmentioning

confidence: 99%

“…

Section: Slender Delta Wing Aircraftmentioning

confidence: 99%

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Separated and vortical flow in aircraft aerodynamics: a CFD perspective

Rizzi

2023

Aeronaut. j.

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“…USM3D is an unstructured-grid, finite-volume, cell-centered RANS solver 35,36 that has been widely used within NASA, [37][38][39] other U.S. government agencies, 40 and industry 41 as a workhorse for aerodynamic analysis of complex configurations. An enhanced mixed-element version of USM3D 42,43 is used for this study.…”

Section: Iib Usm3dmentioning

confidence: 99%

Grid Convergence for Three Dimensional Benchmark Turbulent Flows

Diskin

Anderson

Pandya

et al. 2018

2018 AIAA Aerospace Sciences Meeting

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Grid convergence studies are performed to establish reference solutions for benchmark three dimensional turbulent flows in support of the ongoing turbulence model verification and validation effort at the Turbulence Modeling Resource website curated by NASA. The benchmark cases are a subsonic flow around a hemisphere cylinder and a transonic flow around the ONERA M6 wing with a sharp trailing edge. The study applies widely-used computational fluid dynamics codes developed and supported at the NASA Langley Research Center: FUN3D, USM3D, and CFL3D. Reference steady-state solutions are computed for the Reynolds-Averaged Navier-Stokes equations with the Spalart-Allmaras turbulence model on families of consistently-refined grids composed of different types of cells. Coarse-to-fine and code-to-code solution variation is described in detail.

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Historical development and use of CFD for separated flow simulations relevant to military aircraft

Rizzi

Luckring

2021

Aerospace Science and Technology

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USM3D Simulations for the F-16XL Aircraft Configuration

Cited by 4 publications

References 22 publications

Separated and vortical flow in aircraft aerodynamics: a CFD perspective

Separated and vortical flow in aircraft aerodynamics: a CFD perspective

Grid Convergence for Three Dimensional Benchmark Turbulent Flows

Historical development and use of CFD for separated flow simulations relevant to military aircraft

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