Scott Michael Larwood
March 2009
Mechanical and Aeronautical Engineering
Dynamic Analysis Tool Development for Advanced Geometry Wind Turbine Blades

Abstract

This dissertation describes work to develop a dynamic analysis code for swept wind turbine blades. Because of their aeroelastic behavior, swept blades offer the potential to increase energy capture and lower fatigue loads. This work was an outgrowth of United States Department of Energy contract on swept blades, where the author used the Adams(trademark) dynamic software. The author based the new code on the National Renewable Energy Laboratory’s FAST code. The new code would allow for lower cost analysis and faster computation times for swept blades compared to Adams. The FAST revisions included the geometry and mode shapes required for the bending and twisting motion of the swept blade. The author also developed a finite-element program to determine mode shapes for the swept blade. The author verified the new code with Adams. The comparisons were favorable; however, the Adams model exhibited more twist. The differences may be attributed to differences in modeling approach. The author attempted to validate the code with field test data; however, uncertainties in the test wind speed and the turbine controller made comparison difficult. The author used the new code to perform preliminary designs of swept rotors for 1.5 MW and 3.0MWwind turbines. The designs showed a 5% increase in annual energy production and a decrease in flap-bending fatigue over the baseline straight-blade designs.