Department of Aerospace Engineering

Wind Turbine Icing

Ice Scaling Laws

In the AERTS lab we are presently working on ice accretion testing of a model wind turbine blade mounted on a rotor test stand. The model test blade was scaled to reproduce local flow and icing conditions at the 95% radial station of the NREL Phase VI Rotor. A modified Ruff scaling method was implemented to scale atmospheric icing conditions that could be generated in a laboratory facility. Scaling laws allowed for reduced testing time as well as a reduced chord length of the blades compared to on-site icing events were implemented. Classical Blade Element Momentum Theory (BEMT) was utilized to correlate inflow conditions at the test facility to actual operating conditions of the NREL Phase VI Rotor. Experimentally obtained rime ice shapes are compared to LEWICE predictions and are used to validate the capability of the facility to reproduce representative icing conditions. The rime ice results matched with predictions to within 1% of both ice thickness and ice extent along the blade surfaces. The effects of angle-of-attack, temperature, liquid water content, and icing time on the final ice shapes were investigated in a parametric study. Experimentally obtained glaze ice shapes are used to demonstrate the severity of the icing events on wind turbine torque. The present work comprises testing procedures and experimental data that can be used for future efforts in ice accretion modeling and testing.

Icing Performance Degradation

In addition, we are testing ½ chord 5 MW wind turbine sections to obtain ice accretion shape castings. The castings will be used for wind tunnel testing of lift, drag and pitching moments. The ultimate objective is to develop empirical tools to predict drag and lift performance degradation due to ice accretion to wind turbines.