Published In

Physics of Fluids

Document Type

Article

Publication Date

3-2016

Subjects

Wind turbines -- Blades, Flow (Fluid dynamics), Mathematical models, Stalling (Aerodynamics), Particle image velocimetry, Orthogonal decompositions

Abstract

To understand the complex flow phenomena over wind turbine blades during stall development, a scaled three-dimensional non-rotating blade model is designed to be dynamically similar to a rotating full-scale NREL 5 MW wind turbine blade. A time-resolved particle imagevelocimetry(PIV) investigation of flowbehavior during the stall cycle examines the processes of stall development and flow reattachment. Proper orthogonal decomposition (POD) and vortex detection techniques are applied to the PIV fields to quantify relevant flow characteristics such as vortex size, separation angle, and separation point throughout a dynamic pitching cycle. The behavior of the POD coefficients provides time scales for the transitional stages which are quantified and compared, revealing that transition from attached flow to full stall is delayed to higher angles of attack and occurs at a higher rate than the transition from full stall to attached flow. The instantaneous flow fields are then reconstructed using the first four POD modes to demonstrate their prominent roles throughout the stall cycle and their ability to capture the general separation behavior over the blade surface.

Description

Copyright 2016 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. along with the following message: The following article appeared in Physics of Fluids and may be found at: http://dx.doi.org/10.1063/1.4942001.

DOI

10.1063/1.4942001

Persistent Identifier

http://archives.pdx.edu/ds/psu/17232

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