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Published August 2015 | metadata_only
Journal Article

Dynamic stall on a pitching and surging airfoil


Vertical axis wind turbine blades undergo dynamic stall due to the large angle of attack variation they experience during a turbine rotation. The flow over a single blade was modeled using a sinusoidally pitching and surging airfoil in a non-rotating frame with a constant freestream flow at a mean chord Reynolds number of 10^5. Two-dimensional, time-resolved velocity fields were acquired using particle image velocimetry. Vorticity contours were used to visualize shear layer and vortex activity. A low-order model of dynamic stall was developed using dynamic mode decomposition, from which primary and secondary dynamic separation modes were identified. The interaction between these two modes was able to capture the physics of dynamic stall and as such can be extended to other turbine configurations and problems in unsteady aerodynamics. Results from the linear pitch/surge frame are extrapolated to the rotating VAWT frame to investigate the behavior of identified flow structures.

Additional Information

© 2015 Springer-Verlag Berlin Heidelberg. Received: 26 February 2015; Revised: 5 July 2015; Accepted: 6 July 2015; Published online: 23 July 2015. This work was supported by the Gordon and Betty Moore Foundation through grant GBMF#2645 to the California Institute of Technology. The authors thank Professor Peter Schmid for his assistance in implementing the dynamic mode decomposition algorithm, Professor Morteza Gharib for the use of the free surface water channel facility, Hsieh-Chen Tsai and Professor Tim Colonius for discussion on the Coriolis effect and Professor John Dabiri for his insight from VAWT field research. Compliance with ethical standards. Conflict of interest: The authors declare that they have no conflict of interest.

Additional details

August 20, 2023
August 20, 2023