Scaled ice accretion experiments on a rotating wind turbine blade

This work presents ice accretion tests 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.

► A total of 17 ice accretion tests on a S809 wind turbine airfoil were conducted. ► Scaling method was applied to reproduce icing conditions of the NREL Phase VI rotor. ► Experimental ice shapes agreed to the LEWICE numerical ice accretion predictions. ► Effects of 4 icing parameters on ice shapes were examined. ► Performance degradations range from 5% to exceeding 70% based on torque measurements.