Remote surface damage detection on rotor blades of operating wind turbines by means of infrared thermography

Traphan, Dominik; Herráez, Iván; Meinlschmidt, Peter; Schlüter, Friedrich; Peinke, Joachim; Gülker, Gerd

doi:10.5194/wes-3-639-2018

Cited by 14 publications

(6 citation statements)

References 32 publications

(44 reference statements)

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“…Initially there is an incubation period during which impacts occur but no visible damage is observed, although microstructural changes in the materials generate nucleation sites for material removal, which commences when a threshold is reached (i.e., when some level of accumulated impacts is reached). Once the time to damage has been exceeded, additional damage occurs as stress waves propagate from the impact sites into the composite and cause existing pits and cracks to grow, and there is a steady increase of material loss with each additional impact (Cortés et al, 2017;Eisenberg et al, 2018;Traphan et al, 2018). The number of impacts required to reach the threshold for surface fatigue failure is a function of the droplet diameter and phase, the closing velocity, the strength of the material, and the pressure of the impact.…”

Section: Introduction and Objectivesmentioning

confidence: 99%

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

2020

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Wind turbine blade leading edge erosion (LEE) is a potentially significant source of revenue loss for wind farm operators. Thus, it is important to advance understanding of the underlying causes, to generate geospatial estimates of erosion potential to provide guidance in pre-deployment planning, and ultimately to advance methods to mitigate this effect and extend blade lifetimes. This study focuses on the second issue and presents a novel approach to characterizing the erosion potential across the contiguous USA based solely on publicly available data products from the National Weather Service dual-polarization radar. The approach is described in detail and illustrated using six locations distributed across parts of the USA that have substantial wind turbine deployments. Results from these locations demonstrate the high spatial variability in precipitationinduced erosion potential, illustrate the importance of low-probability high-impact events to cumulative annual total kinetic energy transfer and emphasize the importance of hail as a damage vector.

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Section: Introduction and Objectivesmentioning

confidence: 99%

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

2020

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“…This measurement technique is already in use for a variety of applications in wind tunnel experiments for detecting the laminar-turbulent transition or flow separation [20][21][22][23]. More recent studies begin to use thermography for analyzing surface defects on models of aerodynamic profiles [24,25].…”

Section: State Of the Artmentioning

confidence: 99%

Contactless Localization of Premature Laminar–Turbulent Flow Transitions on Wind Turbine Rotor Blades in Operation

2020

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Thermographic flow visualization enables a noninvasive detection of the laminar–turbulent flow transition and allows a measurement of the impact of surface erosion and contamination due to insects, rain, dust, or hail by quantifying the amount of laminar flow reduction. The state-of-the-art image processing is designed to localize the natural flow transition as occurring on an undisturbed blade surface by use of a one-dimensional gradient evaluation. However, the occurrence of premature flow transitions leads to a high measurement uncertainty of the localized transition line or to a completely missed flow transition detection. For this reason, regions with turbulent flow are incorrectly assigned to the laminar flow region, which leads to a systematic deviation in the subsequent quantification of the spatial distribution of the boundary layer flow regimes. Therefore, a novel image processing method for the localization of the laminar–turbulent flow transition is introduced, which provides a reduced measurement uncertainty for sections with premature flow transitions. By the use of a two-dimensional image evaluation, local maximal temperature gradients are identified in order to locate the flow transition with a reduced uncertainty compared to the state-of-the-art method. The transition position can be used to quantify the reduction of the laminar flow regime surface area due to occurrences of premature flow transitions in order to measure the influence of surface contamination on the boundary layer flow. The image processing is applied to the thermographic measurement on a wind turbine of the type GE 1.5 sl in operation. In 11 blade segments with occurring premature flow transitions and a high enough contrast of the developed turbulence wedge, the introduced evaluation was able to locate the flow transition line correctly. The laminar flow reduction based on the evaluated flow transition position located with a significantly reduced systematic deviation amounts to 22% for the given measurement and can be used to estimate the reduction of the aerodynamic lift. Therefore, the image processing method introduced allows a more accurate estimation of the effects of real environmental conditions on the efficiency of wind turbines in operation.

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“…To avoid premature WTB failure, a range of inspection techniques have been developed and currently used in operation [3,4,6,7]. Infrared thermography (IRT) is one of them [8,9,10,11]. The work presented here is part of an ongoing multi-partner project titled "EvalTherm": the evaluation of passive thermography as a non-destructive inspection tool of WTBs in operation [12].…”

Section: Introductionmentioning

confidence: 99%

Weather-dependent passive thermography and thermal simulation of in-service wind turbine blades

Chaudhuri

Stamm

Krankenhagen

2023

J. Phys.: Conf. Ser.

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To cope with the increase in the manufacturing and operation of wind turbines, wind farm operators need inspection tools that are able to provide reliable information while keeping the downtime low. Current inspection techniques require the wind turbine to be stopped. This work presents the current progress in the project EvalTherm, in which passive thermography is evaluated as a possible non-destructive inspection tool for operational wind turbine blades (WTBs). A methodology to obtain thermal images of rotating WTBs has been established in this project. However, the quality of the results is heavily dependent on various aspects such as weather conditions, information on the inspected WTB, damage history, etc. In this work, a section of a used WTB is simulated using finite-element modelling (FEM) as well as experimentally tested for evaluating the accuracy of the model. Such a model will provide insight into the potential thermal response of a certain structure (with specific material properties) in given weather (boundary) conditions. The model is able to provide satisfactory predictions of the temporal thermal response of the structure, as well as indicate what thermal contrast(s) transients result from artificial defects introduced in the structure.

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Remote surface damage detection on rotor blades of operating wind turbines by means of infrared thermography

Cited by 14 publications

References 32 publications

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

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

Contactless Localization of Premature Laminar–Turbulent Flow Transitions on Wind Turbine Rotor Blades in Operation

Weather-dependent passive thermography and thermal simulation of in-service wind turbine blades

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