Conceptual Design of a Stall-Regulated Rotor for a Deepwater Offshore Wind Turbine

Abstract

A family of stall-regulated wind turbine blades was designed, with a rotor diameter from 44 m to 154 m, and rated power from 1.2 MW to 22.6 MW. These blades were optimized for installation atop a deepwater oating platform, using a simpli ed cost model. The optimization used a numerically-smooth airfoil model and a linear dynamic stall method, with structural dynamic analysis performed in the frequency domain. The analysis methods were validated by comparison against airfoil data, nonlinear calculations, and full-scale measurements on operating turbines. Results show that a deepwater oshore turbine should have a high rated power in comparison to the swept area (approaching 1 kW per square meter), and a thick blade (t/c of 0.30 over most of its length) with spars made of carbon ber. The blade twist and airfoil properties can be tuned such that the blade behaves well in stall, with high apwise and edgewise damping throughout the operating range.