17 Mar 2023
 | 17 Mar 2023
Status: this preprint is currently under review for the journal WES.

Numerical Study of the Unsteady Blade Root Aerodynamics of a 2MW Wind Turbine Equipped With Vortex Generators

Ferdinand Seel, Thorsten Lutz, and Ewald Krämer

Abstract. In order to design vortex generators for modern multi-megawatt wind turbines accurately, the three-dimensional behaviour of the boundary layer has to be considered. Due to the rotation of the blade, the lift-enhancing rotational augmentation has a considerable impact, especially in the inner blade sections. To investigate the interaction of vortex generators and rotational augmentation, high-fidelity computational flow simulations by means of unsteady Reynolds-averaged Navier-Stokes methods are presented for a rotating blade of a generic 2 MW horizontal axis wind turbine. The inner blade section is analysed with and without vortex generators for two different pitch settings including one causing largely separated flow. Two ways of placement of the vortex generators on the blade with different radial starting positions are investigated in order to find out if a coexistence of the two lift-enhancement methods (i.e. rotational augmentation and vortex generators) is beneficial. All simulations are performed with the flow solver FLOWer and the vortex generators are modelled by the introduction of source terms into the computational domain through a BAY-type model. For the case without vortex generators, it is found that the strength of rotational augmentation largely depends on the effective angles of attack (i.e. the pitch setting). For the case with lower effective angles of attack, rotational augmentation is a cyclic phenomenon whereas for the case with higher effective angles of attack it generates large loads in the inner root section due to a constant centrifugal pumping mechanism in time. The results from the cases with vortex generators display a rather destructive interaction of vortex generators and rotational augmentation on the torque. For low effective angles of attack and thus attached flow conditions, vortex generators exhibit slight losses compared to the case without VGs as they inhibit spanwise flow through rotational augmentation. For high effective angles of attack, the vortex generators placed over 30 % of the blade produce an increase of 3.28 % in torque compared to the case without VGs and high centrifugal pumping.

Ferdinand Seel et al.

Status: open (until 14 Apr 2023)

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Ferdinand Seel et al.

Ferdinand Seel et al.


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Short summary
Vortex generators are evaluated on a 2 MW wind turbine rotor blade by computational fluid dynamic methods. Those devices delay flow separation on the airfoils and thus increase their efficiency. On the wind turbine blade, rotational phenomena (e.g. rotational augmentation) appear and interact with the vortices from the vortex generators. The understanding of those interactions is crucial in order to optimise the placement of the vortex generators and evaluate their real efficiency on the blade.