Computational analysis of insect impingement patterns on wind turbine blades

Abstract

Wind turbines experience significant power loss due to insect contamination on the blades. In order to estimate power losses, computational fluid dynamics software or empirical models are used to compute drag increases due to roughness‐induced boundary‐layer transition. These models require knowledge of the expected levels and location of insect contamination on the blade surface. This is generally unknown, making power loss predictions unreliable. The present study develops a computer simulation to predict this information and uses this tool to simulate insect impingement for a variety of turbine operating conditions. The simulation code combines an invsicid panel method with a Lagrangian insect particle simulation module to first solve for the turbine velocity field and then track insect paths through this field. The effects of blade thickness, angle of attack and insect size are studied for 2D airfoil sections. The simulations show that increasing blade thickness leads to a larger chordwise extent of insect impingement yet lower maximum levels of contamination. Increasing insect mass is also found to increase the chordwise extent of impingement. These results are consistent with previous wind tunnel results and theoretical predictions. The model is then applied to a representative 5‐MW turbine model to determine spanwise variation in contamination. Results agree qualitatively with field observation, suggesting that this technique may be used in the future to more accurately predict power losses on turbines. Copyright © 2015 John Wiley & Sons, Ltd.

Effect of Surface Roughness on Wind Turbine Performance

“…The configurations represent different amounts and types of accumulation over time. Roughness is placed between 2% chord on the upper surface and 13% chord on the lower surface [42]. An extended configuration starts at 6% chord on the upper surface, serving as an additional validation case for CFD.…”

“…LEWICE calculates the inviscid flowfield around an airfoil, and then determines ice particle trajectories in a Lagrangian framework. Applying a standard insect drag coefficient, frontal area, and mass to the particles, impingement locations can be cal-culated [42]. A profile normalized by insect mass accumulation is shown in Fig II.10.…”

Damage mitigation techniques in wind turbine blades: A review

“…Multiple-power-level hypotheses. Insect contamination in leading edge of wind blade can cause a significant power loss (Wilcox and White, 2015). To experimentally validate the multiple-power-level hypotheses, two types of blades were considered: (1) leading edge cleaned and (2) leading edge artificial roughened by a zigzag tape of maximum thickness of 1.15 mm (Corten, 2001;Corten and Veldkamp, 2001b).…”

“…It was however suggested that applying non-stick coatings on the blade surface may be the most appropriate means of insect adhesion prevention (Dalili et al, 2009). The recent study in Wilcox and White (2015) presents a computer simulation for predicting the impingement pattern for a variety of turbine operating conditions.…”

Roughness Sensitivity Comparisons of Wind Turbine Blade Sections

“…Insects are most likely to fly during times when wind speed is low but are most likely to rupture at high speeds, so a moderate wind speed of 8 m/s was used. Blade chord length also decreases for outboard sections, resulting in larger values of mass parameter K and higher collection efficiencies at outboard sections [42]. Wind tunnel testing of the NACA 63 3 -418 model was completed by Ehrmann [7] prior to this research, so testing methods for that airfoil are not discussed (although they are similar to the methods described here).…”