Session: 07-04-01 Design and Control of Robots, Mechanisms and Structures I

Paper Number: 70046

Start Time: Monday, 12:05 PM

70046 - Horizontal Axis Wind Rotors With Twisted Blades 

Renewable energy is free of pollutions. It is important to take advantage of renewable energy to protect environment. Wind energy is one of the most reliable renewable energy sources. Wind turbines are mechanical devices that convert kinetic energy of wind into electrical energy. Horizontal axis wind turbines utilize airfoil properties to generate lift force in the plane perpendicular to the span of their blades. The shaft of the electricity generator within a wind turbine is driven by the lift force to produce clean and renewable electric power.

Every differential segment of a blade has its characteristic shape that is indicative of the specific airfoil design. For each airfoil, there exists an optimal angle of attack to generate the maximum force for the parameterized airfoil design. During the design for a fixed twist wind turbine blade, the airfoil and angle of attack are specifically chosen to maximize the torque generated for the system. For the standard wind turbine, an optimal operational wind speed is chosen as a design constraint. Each segment of the wind turbine blade is optimized to generate the maximum force at this speed by specifying the angle of attack at each point along the span of the blade. During the operation of a horizontal axis wind turbine, the speed at any given time is subject to change according to the location and environment. This causes the inherent flaw in standard wind turbine blades as the wind speed experienced by each airfoil segment changes during operation. The change in wind speed leads each blade to generate less force than a blade that is optimized for that specific wind speed. To improve the power conversion efficiency of a horizontal axis wind turbine blade, adjusting the angle of attack for each individual airfoil segment is needed. 

In this paper, the NREL 5MW offshore reference blade is used to study the effects of various optimized twist configurations across a range of wind speeds. The twist configuration of a wind turbine blade is adjusted to match the optimal twist configuration for any oncoming wind speed. Configurations are chosen such that each one has an optimal efficiency at different wind speeds. The dynamic torque of the wind turbine is evaluated in this research to construct the individual power curves of each twist configuration. To improve the efficiency of a dynamically twisted wind turbine blade, the maximum torque value for each twist configuration is combined and compared to the unoptimized NREL 5MW offshore reference blade.

Presenting Author: Hong Zhou Texas A&M University

Authors:

Joseph McGuire Texas A&M University
Hong Zhou Texas A&M University