Influence of Mach number and angle of attack on the two-dimensional transonic buffet phenomenon

Giannelis, Nicholas F.; Levinski, Oleg; Vio, Gareth A.

doi:10.1016/j.ast.2018.03.045

Cited by 52 publications

(30 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Secondly, the unsteadiness captured in Fig. 5a is not harmonic as previously seen for the RBC12 aircraft [19] or in 2D studies for the OAT15A aerofoil [9][10][11][12][13][14][15][16]. Although not shown here, the drag coefficient, C D , and pitching moment coefficient, C M , exhibit similar patterns.…”

Section: Global Forces and Surface Samplingsupporting

confidence: 61%

“…al. [15] found that RSM closures are more robust than typically used Spalart-Allmaras (SA) and Shear Stress Transport (SST) turbulence models for 2D shock-buffet prediction. Steady-state simulations by Apetrei et.…”

mentioning

confidence: 95%

“…With advancing technology, the use of Computational Fluid Dynamics (CFD) in shock-buffet prediction has increased substantially in the last two decades. The 2D experimental results for the OAT15A aerofoil [8] have been used for validation in a series of CFD studies in which the Unsteady Reynolds-averagedNavier-Stokes (URANS), Large Eddy Simulations (LES), and hybrid RANS-LES approaches have been applied [9][10][11][12][13][14][15][16]. The variation in results presented revealed that there is still an uncertainty in prediction of shock-buffet by means of URANS, particularly when closed with eddyviscosity-based turbulence models.…”

mentioning

confidence: 99%

See 2 more Smart Citations

Unsteady shock front waviness in shock-buffet of transonic aircraft

Apetrei

Ciobaca²,

Curiel-Sosa

et al. 2020

Adv. Aerodyn.

View full text Add to dashboard Cite

The unsteady transonic aerodynamics of a wing-body configuration is investigated by solving the Unsteady Reynolds-averaged Navier-Stokes equations closed with the full Reynolds Stress Model. This work presents the prediction of flow field characteristics during deep shock-buffet penetration of a transport aircraftrepresentative geometry. Mach number of 0.85, and Reynolds number of 5 million based on the mean chord, are selected to reproduce experimental test conditions that serve as validating datasets. The results obtained give information about both surface and flow field shock-buffet dynamics. An unsteady shock front is observed on the suction side of the wing which gives birth to the so-called buffet cells. Flow field characteristics are dominated by the presence of lambda-shaped shocks and fully separated boundary layer over a significant part of the wing.

show abstract

Section: Global Forces and Surface Samplingsupporting

confidence: 61%

mentioning

confidence: 95%

mentioning

confidence: 99%

See 1 more Smart Citation

Unsteady shock front waviness in shock-buffet of transonic aircraft

Apetrei

Ciobaca²,

Curiel-Sosa

et al. 2020

Adv. Aerodyn.

View full text Add to dashboard Cite

show abstract

“…A DMD mode at St = 0.44 mainly describes the shock motion, whereas DMD modes at higher frequencies again comprise shock motion as well as acoustic waves. The existence of a bifurcation in the shock dynamics was already suggested by Giannelis et al [44], where at certain flow conditions upstream-propagating pressure waves are periodically generated at the trailing edge at significantly higher frequencies than the co-existing permanent shock wave oscillating at a typical frequency associated with buffet (St ≈ 0.1). 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.…”

Section: Resultsmentioning

confidence: 74%

“…Similar phenomena were reported by Memmolo et al [17] analysing the V2C airfoil at α = 7 • and high Reynolds numbers using large-eddy simulation. In a URANS parameter study exploring the buffet domain varying the angle of attack (3 ≤ α ≤ 9.5) and Mach number (0.55 < M < 0.75), an interesting coexistence between type A and type C shock motion was reported by Giannelis et al [44]. The disturbances associated with the type C shock motion emerged from downstream-convecting recirculation pockets that produced oscillations at the trailing edge at significantly higher frequencies compared to the low-frequency lift oscillation associated with buffet.…”

Section: Dynamic Mode Decompositionmentioning

confidence: 90%

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

Zauner

Sandham

2019

Flow Turbulence Combust

View full text Add to dashboard Cite

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.

show abstract