Transonic flow about a thick circular-arc airfoil

McDevitt, John B.; Levy, Lionel L.; Deiwert, George S.

doi:10.2514/6.1975-878

Cited by 31 publications

(33 citation statements)

References 2 publications

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“…In the present case, no permanent shock wave is apparent so that only type C shock motion is observed, similar to experiments by McDevitt at al. [55]. The DMD modes associated with buffet at St = 0.12 − 0.15 show high fluctuations in the rear part of the airfoil and around x ≈ 0.4, but do not seem to be directly coupled with the shock motion.…”

Section: Resultsmentioning

confidence: 90%

Modal Analysis of a Laminar-Flow Airfoil under Buffet Conditions at Re = 500,000

Zauner

Sandham

2019

Flow Turbulence Combust

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An airfoil undergoing transonic buffet exhibits a complex combination of unsteady shockwave and boundary-layer phenomena, for which prediction models are deficient. Recent approaches applying computational fluid mechanics methods using turbulence models seem promising, but are still unable to answer some fundamental questions on the detailed buffet mechanism. The present contribution is based on direct numerical simulations of a laminar flow airfoil undergoing transonic buffet at Mach number M = 0.7 and a moderate Reynolds number Re = 500,000. At an angle of attack α = 4 • , a significant change of the boundary layer stability depending on the aerodynamic load of the airfoil is observed. Besides Kelvin Helmholtz instabilities, a global mode, showing the coupled acoustic and flow-separation dynamics, can be identified, in agreement with literature. These modes are also present in a dynamic mode decomposition (DMD) of the unsteady direct numerical solution. Furthermore, DMD picks up the buffet mode at a Strouhal number of St = 0.12 that agrees with experiments. The reconstruction of the flow fluctuations was found to be more complete and robust with the DMD analysis, compared to the global stability analysis of the mean flow. Raising the angle of attack from α = 3 • to α = 4 • leads to an increase in strength of DMD modes corresponding to type C shock motion. An important observation is that, in the present example, transonic buffet is not directly coupled with the shock motion.

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Section: Resultsmentioning

confidence: 90%

Modal Analysis of a Laminar-Flow Airfoil under Buffet Conditions at Re = 500,000

Zauner

Sandham

2019

Flow Turbulence Combust

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“…Mach number of 0-771 and Reynolds number of 11 x 10 6 . This Mach number lies within the unsteady found experimentally' 30 ) and computationally' 3 '• 32 >. The C-grid was generated over a modified 18% thick circular arc aerofoil with a 1% radius introduced at the leading edge to remove computational difficulties' 31 -33 ).…”

Section: Code Validation For Periodic Transonic Flowsmentioning

confidence: 53%

“…The C-grid was generated over a modified 18% thick circular arc aerofoil with a 1% radius introduced at the leading edge to remove computational difficulties' 31 -33 ). A rounded leading edge has been used in experiments on biconvex aerofoils' 30 ' and it has been confirmed' 34 ' that periodic flows are totally unaffected by conditions at the leading edge of the aerofoil. The minimum normal grid spacing was reduced to 5 x 10 -6 chords, ensuring a value of y* < 5 everywhere on the aerofoil surface.…”

Section: Code Validation For Periodic Transonic Flowsmentioning

confidence: 99%

Effect of heat transfer on periodic transonic flows

1999

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The effects of the model surface to free stream adiabatic temperature ratio (Tw/Tad) on periodic transonic flow over a 14% thick biconvex aerofoil are evaluated using a computational fluid dynamic approach. The analysis is based on the thin layer Navier Stokes equations with Baldwin-Lomax turbulence model. The results of computations showed that on biconves aerofoils there is a large effect of heat transfer on instantaneous pressure distributions and periodic buffet excitation level confirming some of the available experimental data. The effects observed have an implication in wind tunnel measurement of buffet associated periodic transonic flows.

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“…at several different Mach numbers within or at the upper edge of the unsteady envelop of McDevitt et al [106]. Grid resolution studies were done for case 9, to assess the effect of grid on the solutions.…”

Section: Circular Arc Airfoilmentioning

confidence: 99%

“…43-4.51. This case is done at Moo = 0.773, and Re = 10,000,000, and is near the upper Mach number boundary at which the self-induced oscillation amplitude in the experimental data of McDevitt et al[106] is at a peak. The incompressible C-S turbulence model is used on a 170X140 inviscid grid and 110X520 total boundary layer grid.…”

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confidence: 99%

An interacting boundary layer method for unsteady compressible flows

Bartels

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Transonic flow about a thick circular-arc airfoil

Cited by 31 publications

References 2 publications

Modal Analysis of a Laminar-Flow Airfoil under Buffet Conditions at Re = 500,000

Modal Analysis of a Laminar-Flow Airfoil under Buffet Conditions at Re = 500,000

Effect of heat transfer on periodic transonic flows

An interacting boundary layer method for unsteady compressible flows

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