Large Eddy Simulation of a NACA-0012 Airfoil Near Stall

Almutairi, Jaber H.; AlQadi, Ibraheem; ElJack, Eltayeb

doi:10.1007/978-3-319-14448-1_49

Cited by 9 publications

(9 citation statements)

References 14 publications

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“…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. In the present study, Eljack 23 study, and Almutairi et al 22 work only the pressure component of the force is considered.…”

Section: Resultsmentioning

confidence: 69%

“…The phase shift can also be noted in the work of Almutairi et al, 22 however, the authors did not discuss it. In the present study, Eljack 23 study, and Almutairi et al 22 work only the pressure component of the force is considered. Thus, no phase shift between the lift and the drag is expected.…”

Section: Resultsmentioning

confidence: 69%

“…Also, they showed the quasiperiodic cycle for the lift coefficient which agrees with the experimental observations and measurements of Tanaka 13 and Rinoie and Takemura. 14 Almutairi et al 22 used the method which has been verified by Jones et al 20 and Almutairi et al 19 They performed an LES of the flow field around a NACA-0012 at Re ¼ 1:3 Â 10 5 and a ¼ 11:5 . The authors described the role of transition and how the three-dimensional large scales structures are broken down to small scales, which are followed by turbulent region.…”

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: Resultsmentioning

confidence: 69%

Section: Resultsmentioning

confidence: 69%

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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“…Large Eddy Simulation model was used to model the flow around NACA0015 airfoil in order to give the best agreement with experimental data adopted from [83,99] and [103]. The Large Eddy Simulation model gives excellent results when they are used to simulate the airfoil in stall condition, according to literature survey [70,100,[104][105][106][107][108][109][110].…”

Section: Les Resolution Quality Assessmentmentioning

confidence: 99%

Passive flow control for aerodynamic performance enhancement of airfoil with its application in Wells turbine – Under oscillating flow condition

et al. 2017

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In this work, the passive flow control method was applied to improve the performance of symmetrical airfoil section in the stall regime. In addition to the commonly used first law analysis, the present study utilized an entropy generation minimization method to examine the impact of the flow control method on the entropy generation characteristics around the turbine blade. This work is performed using a time-dependent CFD model of isolated NACA airfoil, which refers to the turbine blade, under sinusoidal flow boundary conditions, which emulates the actual operating conditions. Wells turbine is one of the most proper applications that can be applied by passive flow control method because it is subjected to early stall. Additionally, it consists of a number of blades that have a symmetrical airfoil section subject to the wave condition. It is deduced that with the use of passive flow control, torque coefficient of blade increases by more than 40% within stall regime and by more than 17% before the stall happens. A significantly delayed stall is also observed.

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“…According to literature [70,[88][89][90][91][92][93][94][95], Large Eddy Simulation model excels in predicting flows over airfoil in stall condition. Although LES is a 3D model by definition, there have been numerous successful attempts to use it in 2D applications [6,64].…”

Section: Validation Of the Cfd Modelmentioning

confidence: 99%

Enhancement of performance of wave turbine during stall using passive flow control: First and second law analysis

Shehata

Xiao

et al. 2017

Renewable Energy

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Wells turbine is the most common type of self-rectifying air turbine employed by Oscillating Water Column (OWC) wave energy devices due to its technical simplicity, reliability, and design robustness. Because it subjected to early stall, there were many endeavors to improve the energy extraction performance of Wells turbine within the stall regime. Using the multi suction slots as a passive flow control can help obtaining a delayed stall. Two, three and four suction slots were investigated to improve the performance of Wells turbine in the stall regime. In addition the commonly used first law analysis, the present study utilized an entropy generation minimization method to examine the impact of the multi suction slots method on the entropy generation characteristics around the turbine blade. The turbine blade with optimum suction slots number and location was investigated using the oscillating water system based on the real data from the site. To achieve this purpose, two-dimension numerical models for Wells turbine airfoils under sinusoidal wave flow conditions were built and analyze using (ANSYS FLUENT) solver. It is found that the airfoil with three suction slots located at 40%, 55% and 90% from leading edge in chord percentage give the highest torque coefficient by 26.7% before the stall and 51% after the stall.

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Large Eddy Simulation of a NACA-0012 Airfoil Near Stall

Cited by 9 publications

References 14 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

Passive flow control for aerodynamic performance enhancement of airfoil with its application in Wells turbine – Under oscillating flow condition

Enhancement of performance of wave turbine during stall using passive flow control: First and second law analysis

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