Designing for the Rough as well as the Smooth
Optimal performance of wind turbine blades is critical to ensuring cost-effective power delivery. Aerodynamic behaviour plays a major role in overall efficiency, giving rise to highly refined blade section shapes designed to maximise energy capture. However, with increased performance comes increased sensitivity to changes in operating conditions. This article discusses studies of increasing surface roughness of turbine rotor blades over time and how the effects of the roughness can be modelled
By Chris Langel, Raymond Chow and C.P. van Dam, Department of Mechanical and Aerospace Engineering, University of California, Davis, USA
One of the changes in operating conditions observed over time is the contamination of the leading edge of turbine blades due to insect and soil build-up, paint chipping and erosion of the surface. A well-known effect of a rough surface is the acceleration of the laminar–turbulent transition process. The early introduction of a turbulent boundary layer can have a number of undesirable consequences by altering lift and stall characteristics. The changes in the flow over degraded portions of a turbine blade can extend to the performance of the full turbine, reducing power output and annual energy capture.
