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

Rizzi, Arthur; Luckring, James M.

doi:10.1016/j.ast.2021.106940

Cited by 28 publications

(13 citation statements)

References 49 publications

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“…In general, the issues of developing an effective model for calculating the slip coefficients of a mechanical vehicle with two steering axles require further research in connection with the introduction of various technical improvements in the design of both such machines themselves and their suspension and transmission of lubricant are of considerable complexity from the standpoint of creating a qualitative mathematical description of this process [14].…”

Section: Discussionmentioning

confidence: 99%

Development of a Model for Calculating the Slip Coefficients of a Mechanical Wheeled Vehicle with Two Steering Axles

Bekenov¹,

Nussupbek²,

Tassybekov³

et al. 2022

Communications

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The purpose of the study is to perform appropriate calculations of the values of the total slip coefficients alternately on the sides of a vehicle, depending on the angles of rotation of its axles, using the single slip coefficients of its individual wheels directly when turning. The basis of the methodological approach in this study is a combination of system analysis of the principles of calculating the slip coefficients of a mechanical wheeled vehicle with an analytical investigation of problematic aspects of developing a model for calculating the slip coefficients of a vehicle with two steering axles. The results obtained indicate the presence of a persistent relationship between the slipping coefficients of a mechanical wheeled vehicle and the rotation angles of its two steering axles, including a number of other parameters that are important from the standpoint of traffic safety.

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Section: Discussionmentioning

confidence: 99%

Development of a Model for Calculating the Slip Coefficients of a Mechanical Wheeled Vehicle with Two Steering Axles

Bekenov¹,

Nussupbek²,

Tassybekov³

et al. 2022

Communications

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“…RANS simulations of separated flows apparently have reached a level of diminishing returns as regards capability and certainty, as indicated by the knee in the development curve in Fig. 7 after 2000 [35]. Many CFD predictions of separated flows will require hybrid RANS/LES technology and even higher levels of physical modeling.…”

Section: Physical Modelingmentioning

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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“…Based on the tunnel test materials of the airframe model [15], the value of the product of KspCLsp is determined, which represents the coefficient of the horizontal stabilizer lift force related to the square of the airframe's airspeed. Usually, the value of the horizontal stabilizer lifting force is determined from the difference of the tilting moment of the airframe with and without the stabilizer.…”

Section: Longitudinal Stabilitymentioning

confidence: 99%

“…The lifting rotor allows upward and downward flight, and the fuselage tilts to the right and left [15].…”

Section: Introductionmentioning

confidence: 99%

Analysis of Static Stability and Maneuverability of a New Type of Gyroplane

Łusiak

2022

Adv. Sci. Technol. Res. J.

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

Cited by 28 publications

References 49 publications

Development of a Model for Calculating the Slip Coefficients of a Mechanical Wheeled Vehicle with Two Steering Axles

Development of a Model for Calculating the Slip Coefficients of a Mechanical Wheeled Vehicle with Two Steering Axles

Separated and vortical flow in aircraft aerodynamics: a CFD perspective

Analysis of Static Stability and Maneuverability of a New Type of Gyroplane

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