An Innovative Design of a Microtab Deployment Mechanism for Active Aerodynamic Load Control

Kuo-Chang Tsai,Cheng-Tang Pan,C Van Dam,Scott Johnson,Aubryn Cooperman

doi:10.3390/en8065885

Kuo-Chang Tsai, Cheng-Tang Pan + Show 3 more

Open Access

https://doi.org/10.3390/en8065885

Copy DOI

Abstract

This study presents an innovative design of a microtab system for aerodynamic load control on horizontal-axis wind-turbine rotors. Microtabs are small devices located near the trailing edge of the rotor blades and enable a rapid increase or decrease of the lift force through deployment of the tabs on the pressure or suction side of the airfoil, respectively. The new system has been designed to replace an earlier linearly-actuated microtab mechanism whose performance was limited by space restrictions and stiction. The newly-designed microtab system is based on a four-bar linkage that overcomes the two drawbacks. Its improved kinematics allows for the tab height to increase from 1.0% to 1.7% of the airfoil chord when fully deployed, thereby making it more effective in terms of aerodynamic load control. Furthermore, the modified four-bar link mechanism provides a more robust and reliable mechanical structure.

Highlights

Wind turbines have been used to convert wind energy worldwide
The innovative microtab presented here conquers two major difficulties in existing microtabs: First, it allows the tab height to increase from 1.0% chord to 1.7% chord, thereby enhancing its effectiveness in controlling lift
The existing microtab system tested at the University of California Davis (UCD) [8] involves small tabs that are deployed perpendicular to the blade surface, near the trailing edge of the wind turbine airfoil (Figures 2 and 3)

Summary

Introduction

Wind turbines have been used to convert wind energy worldwide. As the most accessible sites with the best wind resources are rapidly being occupied, wind turbines are beginning to be installed in locations with lower wind speeds or less accessibility, such as offshore sites [1]. To increase the energy capture and to reduce the cost, improvements in wind turbine design become critical. The need to reduce the cost of wind energy leads to a demand for larger rotors in order to increase wind capture at greater heights. Effective aerodynamic control of unwanted loads can lead to lower ultimate and fatigue loads along the blade. By extending the lifetime of a conventional 1.5 MW wind turbine by one year, approximately $200,000 in additional electric energy can be captured. This results in a reduction of the overall cost of energy on a per-turbine basis, thereby making wind energy more competitive [3]

Methods

Results

Conclusion