Delayed Detached Eddy Simulation of a Stall Flow Over NACA0012 Airfoil Using High Order Schemes

Im, Hongsik; Zha, Gecheng; Gables, Coral

doi:10.2514/6.2011-1297

Cited by 20 publications

(15 citation statements)

References 19 publications

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“…Gao et al [21] performed 2.5D LES simulations of the flow field around a single static airfoil and found that the 2D model is not adequate for predicting unsteady flow structures with large-scale separations around airfoils at relatively high AOAs. Furthermore, Travin et al [22], Bertagnolio et al [23], and IM and Zha [24] presented simulations of a single airfoil beyond stall using the DES method, which is essentially a hybrid model of RANS and LES. Results of the 2.5 DES model are clearly superior over those of the 2.5D URANS models.…”

Section: Introductionmentioning

confidence: 99%

2.5D large eddy simulation of vertical axis wind turbine in consideration of high angle of attack flow

Zhu

et al. 2013

Renewable Energy

185

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A renewed interest in vertical axis wind turbines (VAWTs) has been seen recently. Computational fluid dynamics (CFD) is regarded as a promising technique for aerodynamic studies of VAWTs. In particular, 2D unsteady Reynolds-averaged Navier-Stokes (URANS) is commonly adopted, although past studies on VAWTs revealed the limited accuracy of 2D URANS. This paper investigated the feasibility and accuracy of three different CFD approaches, namely 2D URANS, 2.5D URANS and 2.5D Large Eddy Simulations (LES), in the aerodynamic characterization of straight-bladed VAWT (SBVAWT), with a focus on the capability of the 2.5D LES approach in CFD simulation of high angle of attack (AOA) flow. The 2.5D model differs from a full 3D model in that only a certain length of blades is modeled with periodic boundaries at the two extremities of the domain. The applications of these three approaches were systematically examined in the aerodynamic simulations of a single static airfoil and a 3-blade SBVAWT at different rotating speeds. Their capabilities to predict the aerodynamic forces were evaluated through a comparison with the wind tunnel results obtained by other researchers, with particular attention to high AOA flow beyond stall. Among the three methods, 2.5D LES yielded the best agreement with the experimental results in both cases. Detailed examinations of simulated flow field revealed that 2.5D LES produces more realistic 3D vortex diffusion after flow separation, resulting in more accurate predictions of aerodynamic coefficients in static or dynamic stall situations. It is noteworthy that 2.5D LES cannot capture the effect of tip vortex and vertical flow divergence in VAWTs, which used to be regarded by some researchers as the major cause of overprediction of VAWT power in 2D URANS. In this study, the considerably improved results achieved by 2.5D LES imply that the poor accuracy of URANS method is mainly due to its inherent limitation in vortex modeling. In general, 2.5D LES showed good agreement with experimental results at a relatively low tip speed ratio (TSR), but only fair agreement at a high TSR. Compared with the other two approaches, 2.5D LES is regarded as a more promising and effective CFD tool for investigating the aerodynamic characteristics of VAWTs, particularly their self-starting features corresponding to very low rotation speeds.

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Section: Introductionmentioning

confidence: 99%

2.5D large eddy simulation of vertical axis wind turbine in consideration of high angle of attack flow

Zhu

et al. 2013

Renewable Energy

185

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“…A set of 4th order and 6th order central differencing schemes are devised to match the same stencil width of the WENO schemes for the viscous terms [19,20]. For turbulent simulations, FASIP has implemented Detached Eddy Simulation (DES) [21,22,23,24,25,26,27], Large Eddy Simulation(LES) [20,28], and Reynolds averaged Navier-Stokes (RANS) [29,19,30,31,32,33,34,35]. An implicit 2nd order time accurate scheme with pseudo time and unfactored Gauss-Seidel line relaxation is employed for time marching.…”

Section: Methodsmentioning

confidence: 99%

Near field Sonic Boom calculation of Benchmark Cases

Gan

Zha²

2015

53rd AIAA Aerospace Sciences Meeting

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This paper validates the accuracy of a high order accuracy CFD code on predicting near field signatures of sonic boom propagation. The flow near the body is solved using a structured grid Euler solver with low diffusion E-CUSP schemes, 3rd order MUSCL scheme, and 3rd and 5th order WENO schemes. Three benchmark cases, including two non-lifting models and one lifting model, are calculated. The predicted results are in good agreement with that of experiment data. For the Delta wing configuration, the mesh provided by the workshop generates a smooth expansion wave at the off-track plane. When the mesh is refined, a shock coalesced by the compression waves from the wing tip is captured and it generates a weak shock wave interacting with the expansion.

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“…The validation of current DDES methodology for the stalled flow over NACA0012 airfoil at 45 • angle of attack was conducted by the present authors [8]. The DES predicts the drag accurately compared to the experiment, whereas the URANS model overpredicts the drag by about 33%.…”

Section: Delayed Detached Eddy Simulationmentioning

confidence: 98%

“…By using the RANS model near walls, the mesh size as well as the CPU time can be tremendously reduced. It is shown [6,7,8] that the use of hybrid RANS/LES approaches is very effective for the large structure of vortical flow predictions. In [9], DES is used to simulate the spike stall inception of a transonic rotor.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Non-synchronous Vibration Mechanism for a High Speed Axial Compressor Using Delayed DES

Zha

2014

52nd Aerospace Sciences Meeting

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This paper uses the delayed detached eddy simulation (DDES) of turbulence to investigate the mechanism of non-synchronous vibration (NSV) of a multistage high speed axial compressor. DDES is a hybrid model for turbulence simulation, which uses RANS model within the wall boundary layer and uses large eddy simulation outside of the wall boundary layer. Time accurate Navier-Stokes equations are solved with a 3rd order WENO reconstruction for the inviscid flux and a 2nd order central differencing for the viscous terms. A fully conservative rotor/stator sliding BC is used to resolve the unsteady interaction between the rotor and the stationary blades. A 1/7th annulus sector is employed with the time shifted phase lag BC at the circumferential boundaries. The DDES shows that the NSV of the compressor occurs due to the rotating flow instability in the vicinity of the rotor tip at a stable operation condition. The tornado-like tip vortex causes the NSV of the rotor blades as it propagates to the next blade passage in the counter rotating direction above 80% rotor span. The tornado vortex travels fast on the suction surface of the blade and stays relatively longer at the passage outlet crossing to the next blade leading edge. Such a tornado vortex motion trajectory generates two low pressure regions due to the vortex core positions, one at the leading edge and one at the trailing edge, both are oscillating due to the vortex coming and leaving. These two low pressure regions create a pair of coupling forces that generates a torsion moment causing NSV.

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Delayed Detached Eddy Simulation of a Stall Flow Over NACA0012 Airfoil Using High Order Schemes

Cited by 20 publications

References 19 publications

2.5D large eddy simulation of vertical axis wind turbine in consideration of high angle of attack flow

2.5D large eddy simulation of vertical axis wind turbine in consideration of high angle of attack flow

Near field Sonic Boom calculation of Benchmark Cases

Investigation of Non-synchronous Vibration Mechanism for a High Speed Axial Compressor Using Delayed DES

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