Modeling Dynamic Stall on Wind Turbine Blades under Rotationally Augmented Flow Fields

Srinivas Guntur, Niels Sorensen, Leonardo Bergami, Scott Schreck

Research output: NRELTechnical Report


It is well known that airfoils under unsteady flow conditions with a periodically varying angle of attack exhibit aerodynamic characteristics different from those under steady flow conditions, a phenomenon commonly known as dynamic stall. It is also well known that the steady aerodynamic characteristics of airfoils in the inboard region of a rotating blade differ from those under steady two-dimensional (2D) flow conditions, a phenomenon commonly known as rotational augmentation. This paper presents an investigation of these two phenomena together in the inboard parts of wind turbine blades. This analysis is carried out using data from three sources: (1) the National Renewable Energy Laboratory's Unsteady Aerodynamics Experiment Phase VI experimental data, including constant as well as continuously pitching blade conditions during axial operation, (2) data from unsteady Delayed Detached Eddy Simulations (DDES) carried out using the Technical University of Denmark's in-house flow solver Ellipsys3D, and (3) data from a simplified model based on the blade element momentum method with a dynamic stall subroutine that uses rotationally augmented steady-state polars obtained from steady Phase VI experimental sequences, instead of the traditional 2D nonrotating data.
Original languageAmerican English
Number of pages28
StatePublished - 2015

NREL Publication Number

  • NREL/TP-5000-63925


  • aerodynamics
  • CFD
  • dynamic stall
  • NREL
  • NREL
  • rotational augmentation
  • unsteady aerodynamics experiment phase vi
  • unsteady DDES
  • wind energy


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