Hybrid RANS–LES wake studies of an airfoil in stall

Illi, Sebastian A.; Gansel, Philipp P.; Lutz, Thorsten; Krämer, Ewald

doi:10.1007/s13272-012-0050-z

Cited by 10 publications

(4 citation statements)

References 17 publications

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“…There are many investigations on flow separation from airfoils and wings [5][6][7][8][9][10][11][12][13], and dedicated experiments are available to verify numerical methods with regard to the prediction of pressure distribution, boundary-layer development, and separation. But, there are only few studies on the development of the separated wake and its spectrum downstream of the trailing edge [14,15]. Experimental investigations on the development of the unsteady wake flowfield are limited to measurements on airfoils at low Reynolds numbers [16].…”

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confidence: 99%

Prediction and Measurement of the Common Research Model Wake at Stall Conditions

Lutz

Gansel

Waldmann

et al. 2016

Journal of Aircraft

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The development of the unsteady wake of transport aircraft under stall conditions and its impact on the empennage are challenging to predict, and the flow physics is far from being understood. In the European Strategic Wind Tunnels Improved Research Potential project, time-resolved particle image velocimetry measurements on the separated wake of the NASA Common Research Model were performed in the cryogenic European Transonic Windtunnel for flight Reynolds number conditions supplemented by aerodynamic measurements for a great variety of inflow conditions. In the time-resolved particle image velocimetry measurements, both low-speed stall (M ∞ 0.25, Re 11.6∕17 million) and high-speed stall conditions (M ∞ 0.85, Re 19.8∕30 million) were considered and the frequency resolution was as high as 1 kHz, enabling a sufficient characterization of the turbulent wake spectrum. For selected high-and low-speed stall conditions, hybrid Reynolds-averaged Navier-Stokes/large-eddy simulations were performed. In the present paper, the numerical results are discussed and compared to the experiments and first evaluations of the particle image velocimetry data are presented. NomenclatureYoung modulus M ∞ = freestream Mach number q = dynamic pressure Re = Reynolds number based on the reference chord length S = wing reference area Sr = Strouhal number based on the reference chord length and freestream velocity t = time U = velocity U ∞ = freestream velocity x, y, z = Cartesian coordinates y = wall distance normalized by the viscous length scale α = angle of attack Δ = filter width in large-eddy simulations η = spanwise position normalized by the semispan of the wing ω = vorticity

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Prediction and Measurement of the Common Research Model Wake at Stall Conditions

Lutz

Gansel

Waldmann

et al. 2016

Journal of Aircraft

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“…The improved version of DES, such as the delayed DES (DDES), has largely solved the grey zone problems inherited in DES. [13][14][15] Another alternative to the classic LES in non-zonal method category is called wall-modelled LES (WMLES) method. 15 It applies a RANS model to cover the very near-wall boundary layer and then switches to the LES formulation for the main part of the boundary layer once the grid spacing becomes sufficient to resolve the local scales.…”

Section: Numerous Hybrid Rans/les Methods Have Beenmentioning

confidence: 99%

Embedded large eddy simulation of transitional flow over NACA0012 aerofoil

Lin

Wang

Savill

2020

Proceedings of the Institution of Mechanical Engineers, Part G:

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An accurate computation of near-field unsteady turbulent flow around aerofoil is of outstanding importance for aerofoil trailing edge noise source prediction, which is a representative of main contributor to airframe noise and fan noise in modern commercial aircraft. In this study, an embedded large eddy simulation (ELES) is fully implemented in a separation-induced transitional flow over NACA0012 aerofoil at a moderate Reynolds number. It aims to evaluate the performance of the ELES method in aerodynamics simulation for wall-bounded aerospace flow in terms of accuracy, computational cost and complexity of implementation. Some good practice is presented including the special treatments at RANS-LES interface to provide more realistic turbulence generation in LES inflow. A comprehensive validation of the ELES results is performed by comparing with the experimental data and the wall-resolved large eddy simulation results. It is concluded that the ELES method could provide sufficient accuracy in the transitional flow simulations around aerofoil. It is proved to be a promising alternative to the pure LES for industrial flow applications involving wall boundary layer due to its significant computational efficiency.

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“…A number of studies have been dedicated to assessing the efficiency and accuracy of various unsteady Reynolds-averaged Navier-Stokes (URANS) methods in capturing shock buffet [9,10]. In their studies, the numerical schemes [11], turbulence models [11][12][13][14][15], time-step sizes [16], and grids [10,16,17] have all been shown to be crucial in predicting shock oscillation. Recently, Giannelis et al [18,19] also carried out the relevant transonic buffet simulations using the URANS method based on Menter's k-ω SST turbulence model [20] and obtained a good prediction in buffet frequency and shock oscillation amplitude.…”

Section: Introductionmentioning

confidence: 99%

Cooperation of Trailing-Edge Flap and Shock Control Bump for Robust Buffet Control and Drag Reduction

2022

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At transonic flight conditions, the buffet caused by the interaction between the shock waves and the boundary layers can degrade an aircraft’s aerodynamic performance and even threaten its safety. In this paper, the shock control bumps, originally designed to reduce the wave drag at cruise speeds, are applied to enhance the robustness of the closed-loop buffet control system using the trailing-edge flap. For the OAT15A supercritical airfoil, a closed-loop buffet control system is first designed with a feedback signal of lift coefficient. Then, the shock control bumps designed for drag reduction are integrated into the active buffet control system. The results show that the closed-loop flap control can be greatly enhanced by coupling with the shock control bumps. At the steady state under control, the shock control bumps can slightly increase the airfoil lift–drag ratio. More importantly, the ranges of control parameters that can effectively suppress the buffet are significantly enlarged with the help of the bumps; thus, the robustness of the control system is greatly enhanced.

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Hybrid RANS–LES wake studies of an airfoil in stall

Cited by 10 publications

References 17 publications

Prediction and Measurement of the Common Research Model Wake at Stall Conditions

Prediction and Measurement of the Common Research Model Wake at Stall Conditions

Embedded large eddy simulation of transitional flow over NACA0012 aerofoil

Cooperation of Trailing-Edge Flap and Shock Control Bump for Robust Buffet Control and Drag Reduction

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