Publication Date

2011

Document Type

Thesis

Committee Members

George Huang (Committee Member), James Menart (Advisor), Joseph Shang (Committee Member)

Degree Name

Master of Science in Engineering (MSEgr)

Abstract

Wind energy is an abundant natural resource that people have been trying to tap in recent decades. More and more wind turbines are being built to solve the world's energy shortage problem. For a wind turbine, power extracted from the wind by the rotor and the torque applied to the wind turbine blades are important issues in the design process. Thus there is a need to predict the performance of wind turbine blades using computer modeling. This work shows the results of a computational fluid dynamic simulation developed to predict the air flow field and associated aerodynamic quantities around the moving blades of a wind turbine.

The commercial software package SolidWorks was used to construct the geometrical model. Two commercial CFD codes, SC/Tetra and FLUENT, were used to do the fluid simulations. This work was performed in two phases. First a two-dimensional airfoil simulation was modeled to investigate the aerodynamic coefficients Cl, Cd, and Cm for the S809 airfoil. Validation of the CFD model was also examined. The second phase of this modeling work was a three-dimensional model of the flow around the NREL (National Renewable Energy Laboratory) Phase VI wind turbine rotor, which is a horizontal axis wind turbine with two blades using an S809 airfoil. In the three-dimensional model, both rotating blades were simulated. Power extracted from the wind by the rotor, torque on the blades due to the wind, pressure distributions on the blades, and air flow velocity distributions around the blades are the results presented in this work. Comparisons between results obtained from numerical computations and those from the experimental investigation and previous computational investigations are in a good agreement.

Subsequently, using FLUENT codes a detailed study of the effect of yaw angle on power extraction and blade torque was performed. Results are presented for yaw angles of 0°, 10°, 20°, 30°, and 60° and wind speeds of 7m/s, 10m/s, 13m/s, 15m/s, 20m/s, and 25m/s. These results show that yaw angles up to 20° do not cause more than a 2% reduction in power extraction, indicating that wind turbines do not have to be perfectly aligned with the wind for good operation. This is beneficial in practice because it may be difficult to align the wind turbine with the wind direction under the condition of rapidly changing wind directions.

Page Count

124

Department or Program

Department of Mechanical and Materials Engineering

Year Degree Awarded

2011

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