Investigation of aerodynamic braking devices for wind turbine applications

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This report documents the selection and preliminary design of a new aerodynamic braking system for use on the stall-regulated AWT-26/27 wind turbines. The goal was to identify and design a configuration that offered improvements over the existing tip brake used by Advanced Wind Turbines, Inc. (AWT). Although the design objectives and approach of this report are specific to aerodynamic braking of AWT-26/27 turbines, many of the issues addressed in this work are applicable to a wider class of turbines. The performance trends and design choices presented in this report should be of general use to wind turbine designers who are ... continued below

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Griffin, D.A. April 1, 1997.

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This report is part of the collection entitled: Office of Scientific & Technical Information Technical Reports and was provided by UNT Libraries Government Documents Department to Digital Library, a digital repository hosted by the UNT Libraries. It has been viewed 94 times . More information about this report can be viewed below.

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  • Griffin, D.A. R. Lynette & Associates, Seattle, WA (United States)

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Description

This report documents the selection and preliminary design of a new aerodynamic braking system for use on the stall-regulated AWT-26/27 wind turbines. The goal was to identify and design a configuration that offered improvements over the existing tip brake used by Advanced Wind Turbines, Inc. (AWT). Although the design objectives and approach of this report are specific to aerodynamic braking of AWT-26/27 turbines, many of the issues addressed in this work are applicable to a wider class of turbines. The performance trends and design choices presented in this report should be of general use to wind turbine designers who are considering alternative aerodynamic braking methods. A literature search was combined with preliminary work on device sizing, loads and mechanical design. Candidate configurations were assessed on their potential for benefits in the areas of cost, weight, aerodynamic noise, reliability and performance under icing conditions. As a result, two configurations were identified for further study: the {open_quotes}spoiler-flap{close_quotes} and the {open_quotes}flip-tip.{close_quotes} Wind tunnel experiments were conducted at Wichita State University to evaluate the performance of the candidate aerodynamic brakes on an airfoil section representative of the AWT-26/27 blades. The wind tunnel data were used to predict the braking effectiveness and deployment characteristics of the candidate devices for a wide range of design parameters. The evaluation was iterative, with mechanical design and structural analysis being conducted in parallel with the braking performance studies. The preliminary estimate of the spoiler-flap system cost was $150 less than the production AWT-26/27 tip vanes. This represents a reduction of approximately 5 % in the cost of the aerodynamic braking system. In view of the preliminary nature of the design, it would be prudent to plan for contingencies in both cost and weight.

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OSTI as DE97000234

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  • Other Information: PBD: Apr 1997

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  • Other: DE97000234
  • Report No.: NREL/SR--440-22253
  • Grant Number: AC36-83CH10093
  • DOI: 10.2172/464145 | External Link
  • Office of Scientific & Technical Information Report Number: 464145
  • Archival Resource Key: ark:/67531/metadc676003

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Office of Scientific & Technical Information Technical Reports

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  • April 1, 1997

Added to The UNT Digital Library

  • July 25, 2015, 2:21 a.m.

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  • March 31, 2016, 8:12 p.m.

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Griffin, D.A. Investigation of aerodynamic braking devices for wind turbine applications, report, April 1, 1997; Golden, Colorado. (digital.library.unt.edu/ark:/67531/metadc676003/: accessed December 16, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.