A computational framework for the analysis of rain-induced erosion in wind turbine blades, part I: Stochastic rain texture model and drop impact simulations

Abstract

In the past decade, the power output of wind turbines has increased significantly. This increase has been primarily achieved through manufacturing larger blades resulting in high blade tip velocities and increased susceptibility to rain erosion. This paper is the first part in a two-part paper that presents a framework for the analysis of rain erosion in wind turbine blades. Two ingredients of the framework are presented. A stochastic rain texture model is developed to generate three-dimensional fields of raindrops consistent with the rainfall history at the turbine location by integrating the micro-structural properties of rain, i.e. raindrops size and spatial distribution with its integral properties such as the relationship between the average volume fraction of raindrops and rain intensity. An in-house GPU-accelerated computational fluid dynamics model of free-surface flows and a multi-resolution strategy are used to calculate the drop impact pressure as a function of time and space. An interpolation scheme is finally proposed to find the time evolution of impact pressure profile for any given drop diameter using the high fidelity simulation results, significantly reducing the computational cost. Other ingredients of the framework pertaining to drop impact-induced stresses and the blade coating fatigue life are presented in part II.

Radar-derived precipitation climatology for wind turbine blade leading edge erosion

“…1). LEE is likely to present a growing issue within the US wind industry as more and larger wind turbines with higher tip-speed ratios are deployed (Amirzadeh et al, 2017a). The current average age of WTs in the US is 9 years (AWEA, 2019), and LEE will be of greater concern as a larger number of WTs move out of the typical 1-to 5-year warranty period (Bolinger and Wiser, 2012;Brown, 2010).…”

Toolbox for optimizing anti‐erosion protective coatings of wind turbine blades: Overview of mechanisms and technical solutions

“…The degradation of surfaces of wind turbine blades is caused by repeated multiple liquid impacts by raindrops, often influenced by sand erosion, insects, moisture, salt and ultraviolet (UV) light exposure, and other effects. The repeated liquid impacts cause the local wave propagation, deformation of coatings, and accumulation of irreversible deformation, which lead to the formation of cracks, fatigue, spalling, and debonding of the coatings . The mechanisms of the erosion are strongly influenced by the direction of the droplet impact, properties of the coating, humidity, temperature, and other effects.…”

“…The repeated liquid impacts cause the local wave propagation, deformation of coatings, and accumulation of irreversible deformation, which lead to the formation of cracks, fatigue, spalling, and debonding of the coatings. [13][14][15] The mechanisms of the erosion are strongly influenced by the direction of the droplet impact, properties of the coating, humidity, temperature, and other effects.…”

Prospective challenges in the experimentation of the rain erosion on the leading edge of wind turbine blades

“…However, this model did not consider multiple raindrop impacts, different impact angles, or residual stresses during blade manufacturing. Recently, Amirzadeh et al developed a computational framework for the analysis of rain erosion on wind turbine blades using a stochastic rain model to generate three‐dimensional domains of raindrops. These generated domains intend to be consistent with the rainfall at specific locations integrating raindrop size and spatial distribution with rain intensity and average volume fraction of raindrops.…”