An Experimental and Computational Approach to Iced Wind Turbine Aerodynamics

Open Access
Author:
Blasco, Peter Michael
Graduate Program:
Aerospace Engineering
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
January 05, 2015
Committee Members:
  • Sven Schmitz, Thesis Advisor
Keywords:
  • wind
  • turbine
  • aerodynamics
  • icing
  • iced
  • wind-tunnel
  • AERTS
  • experiments
  • utility-scale
  • rotor
  • blade
  • XTurb
Abstract:
This thesis presents an analysis of power loss of a representative 1.5 MW wind turbine for variable icing conditions. Power losses are estimated using aerodynamic data obtained in a combination of two experimental methods. Atmospheric icing conditions varying in temperature, droplet size, and liquid water content are generated in an icing facility to simulate a 45-minute icing event on a representative wind turbine airfoil section. The ice shapes are then molded for preservation and subsequent wind-tunnel testing. Lift and drag measurements are made and used to estimate the total power production of the iced wind turbine using a blade-element momentum theory prediction code. Detailed measurements of ice profiles show that aerodynamic penalties are mainly a function of surface roughness due to icing. A 16% loss of airfoil lift at operational angle of attack is observed for freezing-fog conditions. Drag increases at a lift coefficient of 0.5 are observed to be 190% at temperatures near 0°C, 145% near -10° C, and 80% near -20°C. An analysis of the wind turbine aerodynamic loads due to atmospheric icing yields power losses ranging from 16% to 26% near an average wind speed of 8 m/s. An exception to these results exists for a single super-large droplet icing case in which lift decrease and drag increase are more severe at 25% and 219%, respectively. The analysis gives insight to potential control strategies for wind turbine operators attempting to minimize revenue loss in cold-climate operations.