Condition Monitoring of Wind Turbine Blades
Date
2018-03-01
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Abstract
The failure of wind turbine blades is a major concern in the wind power industry due to the resulting high cost. Leading-edge erosion is another issue of blades which may affect their performance and result in energy loss. It is therefore crucial to develop methods to improve the integrity of wind turbine blades and to detect surface and subsurface defects before they can result in blade failure. This research employed laser scanning to reconstruct the surface of the blade to measure leading-edge erosion. Computational Fluid Dynamics simulations were used to determine the deterioration of aerodynamic characteristics resulting from leading-edge erosion. The results suggest that it is possible to successfully evaluate the aerodynamic characteristics of eroded and clean airfoils. Different methods are available to detect subsurface damage in blades but most require close proximity between the sensor and the blade. To address this limitation, the use of thermography as a non-contact method was developed in this study. Both passive and active thermography techniques were investigated for different purposes. Passive thermography can be used to detect internal defects on an operating blade, whereas active thermography is restricted to pre-delivery blade inspection and site inspections when the blades are removed from the turbine. Pulsed and step heating as active thermography methods were studied. The raw thermal images captured by both active and passive thermography demonstrated that image processing was required to improve the quality of thermal data. Different image processing algorithms, including Thermal Signal Reconstruction, Principal Component Thermography, Matched Filters, and Pulsed Phase Thermography, were used to increase the thermal contrasts of subsurface defects in thermal images obtained by active thermography. A method called “Step Heating Phase and Amplitude Thermography”, which applies a transform-based algorithm on step heating data, was developed. This method was also applied to passive thermography results. The outcomes of image processing on both active and passive thermography indicated that the techniques employed could considerably increase the quality of the images and the visibility of internal defects.
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Keywords
Passive Thermography, Active Thermography, Pulsed Thermography, Step Heating Thermography, Wind Turbine Blade, Condition Monitoring, Leading-edge Erosion, Laser Scanning, Computational Fluid Dynamics (CFD), image processing
Citation
Sanati, H. (2018). Condition Monitoring of Wind Turbine Blades. (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/10689