High-fidelity numerical simulation of the flow field around a NACA-0012 aerofoil from the laminar separation bubble to a full stall

ElJack, Eltayeb

doi:10.1080/10618562.2017.1330953

Cited by 13 publications

(16 citation statements)

References 28 publications

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“…Thus, the lift coefficient is leading the drag coefficient by a phase shift of p=2. This agrees with the observations of Eljack 23 inequities of how disturbed the LFO cycle in his study is. The phase shift can also be noted in the work of Almutairi et al, 22 however, the authors did not discuss it.…”

Section: Resultssupporting

confidence: 93%

“…Grid-2 (780 Â 320 Â 125) is a refined version of Grid-1 that was used by Eljack. 23 The grid distribution on the suction surface of the aerofoil was made equidistant starting from the leading-edge to the mid-chord. Grid-3 (832Â 351 Â 167) is a refined version of Grid-2.…”

Section: Computational Setupmentioning

confidence: 99%

“…Recently, Eljack 23 carried out a high-fidelity numerical simulation to investigate the LSB and its associated LFO phenomenon over a NACA-0012 aerofoil at Re c ¼ 5 Â 10 4 and various angles of attack around the onset of stall. He showed that at low angles of attack the LSB is present and intact, at moderate angles of attack the LSB becomes unstable and the flow-field switches between an attached phase and a separated phase at low frequency.…”

Section: Introductionmentioning

confidence: 99%

“…At relatively high angles of attack, he showed that the LSB becomes an open bubble that leads the aerofoil into a full stall. Eljack et al 24 used the data sets generated by Eljack 23 to characterise the flow-field. The authors verified and validated the LES data, then used a conditional time-averaging to describe the flow field in detail and investigate the effects of the angle of attack on the characteristics of the flow field.…”

Section: Introductionmentioning

confidence: 99%

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Numerical investigation of the low-frequency flow oscillation over a NACA-0012 aerofoil at the inception of stall

ElAwad

ElJack

2019

International Journal of Micro Air Vehicles

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High-fidelity large eddy simulation is carried out for the flow field around a NACA-0012 aerofoil at Reynolds number of 9 Â 10 4 , Mach number of 0.4, and various angles of attack around the onset of stall. The laminar separation bubble is formed on the suction surface of the aerofoil and is constituted by the reattached shear layer. At these conditions, the laminar separation bubble is unstable and switches between a short bubble and an open bubble. The instability of the laminar separation bubble triggers a low-frequency flow oscillation. The aerodynamic coefficients oscillate accordingly at a low frequency. The lift and the drag coefficients compare very well to recent high-accuracy experimental data, and the lift leads the drag by a phase shift of p=2. The mean lift coefficient peaks at the angle of attack of 10:25 , in total agreement with the experimental data. The spectra of the lift coefficient does not show a significant low-frequency peak at angles of attack lower than or equal the stall angle of attack (10:25 ). At higher angles of attack, the spectra show two low-frequency peaks and the low-frequency flow oscillation is fully developed at the angle of attack of 11:0 . The behaviour of the flow-field and changes in the turbulent kinetic energy over one low-frequency flow oscillation cycle are described qualitatively.

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Section: Resultssupporting

confidence: 93%

Section: Computational Setupmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Numerical investigation of the low-frequency flow oscillation over a NACA-0012 aerofoil at the inception of stall

ElAwad

ElJack

2019

International Journal of Micro Air Vehicles

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“…Another reason could be the averaging time window which is only on the last t * c = 20 = 40 s in simulations while it is 5 minutes in experiments. When the LSB is a highly instationnary phenomenon and could be subject to intermittency as seen in Eljack [39], the averaging time is critical and longer simulations should be carried out in the future. Figure 15(b) shows that the simulated drag coefficient is in good agreement with all the experiments for each angle of attack.…”

Section: B Incompressible Simulations With Inflow Turbulencementioning

confidence: 99%

Airfoil Noise Numerical Simulations with Direct Noise Computation and Hybrid Methods Using Inflow Synthetic Turbulence

Rigall¹,

Cotté²,

Lafon³

2019

25th AIAA/CEAS Aeroacoustics Conference

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The interaction of inflow turbulence with an airfoil is significant for low Reynolds number applications, as it generates leading edge noise, but also strongly modifies the airfoil boundary layer properties and thus the produced noise. Inflow turbulence impact still demands to be better understood and is also a numerical challenge. Large Eddy Simulations are here carried out with both incompressible and compressible solvers. The Synthetic Eddy Method and the Random Fourier Modes method, used to generate synthetic turbulence, are studied in this work. In order to eventually perform airfoil simulations, the second method is modified to take into account spanwise periodic boundary conditions, to reduce spurious noise level in compressible simulations. First, properties of the methods are studied with a spatially decaying turbulence academic case. Even if the decay is not well represented, the methods show satisfactory properties in terms of isotropy, homogeneity and one-dimensional spectra. Furthermore, spurious noise levels are reduced thanks to the modified method. Preliminary airfoil simulations are then carried out with inflow turbulence for flow validation in presence of a laminar separation bubble. The drag coefficient is in very good agreement with experimental results. However, there are some discrepancies between simulations and experiments on the lift coefficient, which is extremely sensitive to perturbations. These discrepancies are attributed to a lack of experimental turbulence characteristic information, such as isotropy or integral length scale and to too short simulations at high angles of attack. * The Einstein convention is used : subscript repetition implies summation, subscript between brackets avoids it.

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Numerical Investigation of the Enhancement of the Aerodynamic Performance for Newly Modified Blended Airfoils Utilizing S809, S829, and NACA 2412 Baseline Shapes

Uddin,

Haque,

Haque

et al. 2023

Arab J Sci Eng

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High-fidelity numerical simulation of the flow field around a NACA-0012 aerofoil from the laminar separation bubble to a full stall

Cited by 13 publications

References 28 publications

Numerical investigation of the low-frequency flow oscillation over a NACA-0012 aerofoil at the inception of stall

Numerical investigation of the low-frequency flow oscillation over a NACA-0012 aerofoil at the inception of stall

Airfoil Noise Numerical Simulations with Direct Noise Computation and Hybrid Methods Using Inflow Synthetic Turbulence

Numerical Investigation of the Enhancement of the Aerodynamic Performance for Newly Modified Blended Airfoils Utilizing S809, S829, and NACA 2412 Baseline Shapes

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