Numerical Simulations of the F-16XL at Flight-Test Conditions Using Delayed Detached-Eddy Simulation

Lofthouse, Andrew J.; Cummings, Russell M.

doi:10.2514/1.c034045

Cited by 13 publications

(8 citation statements)

References 15 publications

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“…The most challenging pressure distribution for this case was at Butt Line 153.5, which is on the wing outer panel, and predictions from a second KESTREL simulation are shown in Fig. 68 from Lofthouse and Cummings (133) . This unsteady simulation also used adaptive grids.…”

Section: Three-dimensional Flows Sharp or Blunt-leading-edge Vorticementioning

confidence: 99%

The discovery and prediction of vortex flow aerodynamics

Luckring

2019

Aeronaut. j.

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High-speed aircraft often develop separation-induced leading-edge vortices and vortex flow aerodynamics. In this paper, the discovery of separation-induced vortex flows and the development of methods to predict these flows for wing aerodynamics are reviewed. Much of the content for this article was presented at the 2017 Lanchester Lecture and the content was selected with a view towards Lanchester’s approach to research and development.

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Section: Three-dimensional Flows Sharp or Blunt-leading-edge Vorticementioning

confidence: 99%

The discovery and prediction of vortex flow aerodynamics

Luckring

2019

Aeronaut. j.

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“…The unsteady flow simulations from CAWAPI-2 indicated that more detailed unsteady work with finer grid resolution held out promise for simulating the FC-25 case, and it became the focus for the CAWAPI-3 investigations with hybrid RANS-LES modeling. [54]; left, butt line 153.5 computed time mean and variation pressure profiles and flight data [55].…”

Section: Rans Simulationmentioning

confidence: 99%

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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“…The superiority of hybrid RANS/LES methods over RANS could be shown due to an improved prediction of vortical characteristics like the primary vortex core flow characteristics, secondary vortex characteristics, vortex interaction details, and vortex breakdown [1] . Further simulations on this configuration were provided by Lofthouse [6]. In this case, the used hybrid RANS/LES method was a delayed detached eddy simulation (DDES) applying the Spalart-Allmaras (SA) model as background closure.…”

Section: Introductionmentioning

confidence: 99%

Assessment of Hybrid Delta Wing Vortex Flow Investigation – Part I at Subsonic Conditions

Sedlacek

Breitsamter

Visonneau

et al. 2022

AIAA SCITECH 2022 Forum

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The dependencies of numerical simulations regarding grid sensitivity and modelling error for vortex dominated flow need particular investigation. In this study, an extensive investigation on the grid sensitivity is conducted and the influence of different turbulence closures is analyzed. For this purpose, a triple-and a double-delta-wing configuration are considered. In a collaboration between the French National Centre for Scientific Research, the Centrale Nantes Engineering School and the Technical University of Munich, simulations were conducted to identify grid and turbulence closure sensitivities. For the grid sensitivity, a comparison of the global force and moment coefficients and of the local flow in the vortex core is shown. From this, it can be concluded that the local flow is more sensitive to grid adaptation than forces and moments. Furthermore, the double-delta-wing configuration seems to be more affected by grid sensitivity. The comparison of k-𝜔 shear stress model, delayed detached eddy simulation and different grids and background closures indicates a lower influence of grid sensitivity to delayed detached eddy simulations than to k-𝜔 shear stress models. A grid convergence represents an important parameter but for vortex dominated flows, it can only be achieved by a local convergence for the vortex core flow is of primary importance as vortex core flow characteristics strongly determines the accuracy of the moment prediction.

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Numerical Simulations of the F-16XL at Flight-Test Conditions Using Delayed Detached-Eddy Simulation

Cited by 13 publications

References 15 publications

The discovery and prediction of vortex flow aerodynamics

The discovery and prediction of vortex flow aerodynamics

Separated and vortical flow in aircraft aerodynamics: a CFD perspective

Assessment of Hybrid Delta Wing Vortex Flow Investigation – Part I at Subsonic Conditions

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