Technical Brief

Elastic Field and Frequency Variation in Extendable Wind Turbine Blades

[+] Author and Article Information
Jeswin John

Department of Civil and Environmental Engineering,
Colorado State University,
Fort Collins, CO 80523
e-mail: jeswin_john@live.in

Donald W. Radford

Department of Mechanical Engineering,
Colorado State University,
Fort Collins, CO 80523
e-mail: don@engr.colostate.edu

Subhas Karan Venayagamoorthy

Department of Civil and Environmental Engineering,
Colorado State University,
Fort Collins, CO 80523
e-mail: vskaran@colostate.edu

Paul R. Heyliger

Department of Civil and Environmental Engineering,
Colorado State University,
Fort Collins, CO 80523
e-mail: prh@engr.colostate.edu

Contributed by the Solar Energy Division of ASME for publication in the JOURNAL OF SOLAR ENERGY ENGINEERING: INCLUDING WIND ENERGY AND BUILDING ENERGY CONSERVATION. Manuscript received June 20, 2015; final manuscript received May 26, 2016; published online July 12, 2016. Assoc. Editor: Yves Gagnon.

J. Sol. Energy Eng 138(5), 054502 (Jul 12, 2016) (5 pages) Paper No: SOL-15-1194; doi: 10.1115/1.4033985 History: Received June 20, 2015; Revised May 26, 2016

The behaviors of tip displacement, maximum stress, and natural frequency of vibration as a function of blade length are investigated for extendable wind turbine blades. A three-dimensional linear elasticity finite-element model of the blade is used along with a typical profile and representative material properties. The quasi-linear response and free vibration behavior are investigated for a sequence of blade geometries. These estimates are intended to give approximate measures of expected changes in the elastic and dynamic field as the operating length changes and provide preliminary guidelines for this novel class of structure.

Copyright © 2016 by ASME
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Fig. 1

Schematic of the retracted (a) and fully extended (b) turbine blades

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Fig. 4

Maximum transverse shear stress σxz reduction

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Fig. 3

Maximum bending stress σzz reduction

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Fig. 2

Tip deflection under dead and wind loading as a function of percent length reduction

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Fig. 5

Vibrational frequencies of lowest two modes for various blades



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