An Investigation of Damages in Low Power Wind Turbine Blades

Abstract

Data in the literature about the various types of damages in wind turbines which may result during manufacturing or operation is not enough. In the current work, a number of 18 blades of 300 kW and 81 blades of 100 kW power wind turbines are inspected using visual test (VT) and if needed using liquid penetrant test (PT) when needed. The location and size of discontinuities found are measured and documented. Types of discontinuities are categorized into four main ‎groups: 1) Transverse cracks and longitudinal cracks, 2) Hair line surface cracks, coating pores, surface damages, holes or ‎penetrations, 3) Edge cuts or crushing ‎and side separation, and 4) reworked areas.‎ The gathered data are analyzed to allocate the different forms of discontinuities about the blade length, to establish an indication of the rotor blades working conditions. It is found that the transverse carks are concentrated at the highly loaded and geometric change region of trailing edge. Longitudinal cracks up to 59 cm long are detected also at the region of the geometric change; i.e. in the root and the cover of the aerodynamic zone. Edge damages such as edge cuts or crushing and partial side separation are found in the sharp trailing edge. Surface and coating damages are observed on the leading edge due to erosion.