Rain droplet erosion behavior of a thermoplastic based leading edge protection system for wind turbine blades

Abstract

This paper discusses the rain droplet erosion mechanisms of an acrylonitrile butadiene styrene (ABS). Rain droplet impingement was modeled based on a coupled smoothed particle hydrodynamics and finite element method (SPH/FEM). Using linear elastic material parameters at low strain rates, the dynamic stress behavior was studied and the location of damage initiation was predicted. Experiments using a pulsating jet erosion tester were performed and the resulting erosion behavior was analyzed using confocal microscopy. The damage was expected to initiate at the surface and remain superficial during propagation. It was shown that a pitting behavior occurred at the surface after the first few impacts. This pitting continued until 100.000 impacts. After this, the pits connected through a cracking mechanism and finally, at 300.000 impacts, cratering was observed which led to the onset of material loss. The depth of these craters was observed to be approximately 80µm, which was relatively low as compared to the material thickness of 4mm, indicating superficial damage. The resulting volume loss curve showed an initial period where no volume loss occurred, called the incubation period, followed by a linear relation between the volume loss and the number of impacts. This behavior agreed well with behavior found for other materials in literature. The surface roughness parameters were determined for each amount of impacts and the mean roughness value corresponded well to the volume loss behavior. Earlier stages of damage could be detected by analyzing the skewness value.

A Study of Raindrop Impacts on a Wind Turbine Material: Velocity and Impact Angle Effects on Erosion MAPS at Various Exposure Times

“…Until cycle 2, the wear rate is approximately linear, after which the mass loss starts to reduce. This trend can also be found in the literature [21][22][23] and shown in Figure 8, where the erosion of a material is set into three distinct sections: incubation period, steady weight loss rate and final erosion region. From this investigation, it is assumed that the incubation period occurred during the first cycle, as there was instantly mass loss that continued linearly into cycle 2, and cycles 3 and 4 are described by the final erosion region.…”

Pre-impact dynamics of a droplet impinging on a deformable surface

“…For example, rain droplet impact on wind turbines can, over time, lead to significant erosion of the wind turbine blades. 66 Reduced pressure peaks appear to also be significant in reducing splashing, 12 which, in turn, has a number of vital implications, such as in aircraft safety, 1,67 pesticide application, 68 forensic science, 69 and many others. Our results should also help engineer novel non-wetting and protective surfaces where impact pressure plays an important role.…”

The Springer Model for Lifetime Prediction of Wind Turbine Blade Leading Edge Protection Systems: A Review and Sensitivity Study

“…For thermoplastic based protection systems, the damage initiation and propagation mechanisms were studied experimentally and successfully correlated with numerical simulations [ 44 ] in terms of damage type and location. More work towards lifetime prediction, however, is required.…”