Implementation of a Hybrid Navier-Stokes/Vortex Panel Method for ...

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Outline of Talk • Overview of hybrid CFD method • Implementation in CFX • Validation • Sensitivity Studies • Concluding Remarks © 2008 GE All rights reserved. 2
Hybrid CFD for Wind Turbine Aero • Conventional CFD methods based on Navier-Stokes have serious shortcomings for wind turbine analyses – Very large domain required to enforce far-field boundary conditions sufficiently far from blade • Inlet and outlet conditions imposed many blade radii upstream and downstream • Periodicity requires large sector (120° for 3 blades) to be modeled – Results in very large meshes (> 10M nodes), long run times, difficult post-processing • Prevents use of fine enough mesh near blade needed to capture turbulence transition effects • Unsteady CFD simply not practical on such large meshes – Wake behind blade dissipates too quickly due to numerical dissipation • Prior studies have shown need to resolve wake as far as 10-20 blade radii downstream for accurate power predictions © 2008 GE All rights reserved. 3
Page 1: 2008 International ANSYS Conference
Page 5 and 6: Hybrid CFD (cont’d) • Hybrid Na
Page 7 and 8: Goals for Hybrid CFD for Wind Turbi
Page 9 and 10: User Fortran Routines CFX provides
Page 11 and 12: Computing Circulation in CFX • Th
Page 13 and 14: Induced Velocities • The induced
Page 15 and 16: Computation of Induced Velocities
Page 17 and 18: Mesh Generation • The blade geome
Page 19 and 20: Generation of the polylines Screen
Page 21 and 22: NREL Validation Case • National R
Page 23 and 24: Sensitivity Study • Sensitivity s
Page 25 and 26: Future Work • Hybrid methodology
Page 27: Impact Hybrid CFD - Represents a un

Implementation of a Hybrid Navier-Stokes/Vortex Panel Method for ...

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