Dynamic stall analysis using harmonic balance and correlation-basedγ- Reθt¯ transition models for wind turbine applications

Abstract

In this paper, we use the harmonic balance method to study an oscillating S809 airfoil in dynamic stall. The periodic behavior of this problem makes it well suited for the harmonic balance method, which is able to model unsteady aerodynamics at greatly reduced computational costs when compared with time‐accurate unsteady‐flow solvers. A finite‐volume technique based on the lower–upper symmetric Gauss–Seidel scheme with Roe fluxes is used to solve the Reynolds‐averaged Navier–Stokes equations. The turbulent viscosity is computed with the one‐equation Spalart–Allmaras turbulence model. In addition, the laminar–turbulent transition is modeled using a correlation‐based approach originally developed by Langtry and Menter. Comparisons with experimental data for steady flows with the S809 airfoil highlight the necessity of the transition model to accurately predict the onset of static stall. For unsteady cases, the transition model provides improved agreement with experimental data, predicting dynamic stall when the fully turbulent model cannot. Copyright © 2014 John Wiley & Sons, Ltd.

A Turbulent Low-Speed Preconditioner for Unsteady Flows About Wind Turbine Airfoils

“…As can be seen, there is good agreement with the experimental results of Ramsay et al 30 although certain flow features can only be captured with a transition model. 4 As shown in Figure 9, the convergence is significantly improved with the present lowspeed preconditioner compared to the WSCM LSP and the case without any preconditioning. As discussed earlier, although there is only a slight difference between the preconditioned and non-preconditioned results in terms of the surface coefficient, the convergence is significantly accelerated using the present viscous lowspeed preconditioning that effectively incorporates the turbulence model in the preconditioning mechanism.…”

“…Once again, the present technique is capable of shifting the numerical solution toward the experimental data while it is once again proven that the use of a transition model is crucial to achieve better agreement. 4 Having said that, the present preconditioner seems to be useful in accelerating the convergence, which is the main goal of this numerical tool. Convergence histories are given in Figure 18.…”

“…The application of a harmonic balance (HB) method 1 to Navier-Stokes (NS) solvers has proven to be a promising tool for turbomachinery and wind turbine flow problems. [1][2][3][4] The aforementioned HB-NS solver can be enhanced with a one-equation Spalart-Allmaras 5 turbulence model that incorporates a rotation correction that reduces the eddy viscosity in the vicinity of regions where the vorticity surpasses the strain rate. 6,7 The spatial discretization of the convective and diffusive terms includes the central difference formula that can be stabilized and further enhanced with an artificial or numerical dissipation that uses a blend of second and fourth differences.…”

Numerical Simulation of a Pitching Airfoil Under Dynamic Stall of Low Reynolds Number Flow

“…Dynamic Stall Phenomenon (DS) can be simulated by various models. Many researchers (Merz et al 2012;Holierhoek et al 2013;Liu et al 2014;Howison and Ekici 2014;Dyachuk et al 2014 Dyachuk andGoude 2015a;2015b;Antonini et al 2015;Zanon et al 2015;Wang and Zhao 2015;Elgammi and Sant 2016) presented new models to simulate DS, some of them comparing their results with the famous Leishman-Beddoes model. Based on the turbulent nature of the fl ow, it is necessary to couple turbulence equations with basic ones.…”