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Numerical Simulation of Horizontal Axis Wind Turbines with Vortex Generators

  • Hak Min Lee
  • Oh Joon Kwon
Original Paper
  • 13 Downloads

Abstract

In the present study, a simulation about the effects of vortex generators on horizontal axis wind turbine rotor blade was numerically conducted using a static coupled CFD–CSD method. A Navier–Stokes CFD flow solver based on unstructured meshes was used to obtain the blade aerodynamic loads. A FEM-based CSD solver employing a nonlinear coupled flap-lag-torsion beam theory was utilized to calculate the blade elastic deformation. The coupling of the CFD and CSD solvers was accomplished in a loosely coupled manner by exchanging the information between the two solvers at infrequent intervals. The static coupled CFD–CSD method was applied to the NREL 5 MW reference wind turbine rotor under steady axial flow conditions. Triangular counter-rotating vortex generators were adopted to control flow separation and radial flow in the inboard section of the NREL 5 MW reference rotor blades. They were installed on the inboard part of the blade from 0.2 to 0.4 R. As a result of the flow analysis considering the counter-rotating vortex generators, strong vortices were generated by counter-rotating vortex generators. It can be seen that the regions where flow separation and radial flow occur in the inboard sections were reduced compared to the baseline wind turbine. For this reason, the maximum power improvement due to counter-rotating vortex generators was 1.04% at the rated wind speed.

Keywords

Computational fluid dynamics Computational structural dynamics Horizontal axis wind turbine Vortex generators 

List of Symbols

Cp

Surface pressure coefficient

c

Blade chord length

Fn

Sectional normal forces, N/m

Ft

Sectional tangential forces, N/m

R

Rotor radius of blade

u

Spanwise deflection

v

Lead-lag deflection

w

Flap bending deflection

θ

Rigid pitch angle, degree

\( \phi \)

Torsional deformation at elastic axis, degree

Ω

Rotor rotational speed

βp

Precone angle, degree

\( \overset{\lower0.5em\hbox{$\smash{\scriptscriptstyle\rightharpoonup}$}}{Q} \)

Vector of conservative variables

\( \overrightarrow {F} ,\overrightarrow {G} \)

Flux vectors

\( \vec{n} \)

Normal vector

\( \widetilde{K} \)

Preconditioning matrix

\( U \)

Strain energy

\( T \)

Kinetic energy

\( W \)

Virtual energy

\( M \)

Mass matrix

\( G \)

Gyroscopic matrix

\( K \)

Stiffness matrix

Notes

Acknowledgements

This work was supported by the New and Renewable Energy Core Technology Program of the Korea Institute of Energy Technology Evaluation and Planning (KETEP), and financial resource was granted by the Ministry of Trade, Industry and Energy, Republic of Korea (no. 20153030023880). This research was also supported by the Climate Change Research hub of KAIST (Grant no. N11180110).

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Copyright information

© The Korean Society for Aeronautical & Space Sciences 2019

Authors and Affiliations

  1. 1.Department of Aerospace EngineeringKorea Advanced Institute of Science and TechnologyDaejeonRepublic of Korea

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