The infuence of hail on wind turbine blade leading edge erosion and damage

  • Hamish Macdonald

Student thesis: Doctoral Thesis

Abstract

Wind turbine blade damage, particularly leading edge erosion, is a signifcant problem faced by the renewable energy industry. Wind turbines are subject to a wide range of environmental factors during a 20+ year lifespan, with hailstones often touted as a key contributor to the deterioration of blade profile. The consequences of blade damage are exhibited in terms of cost of component repair but, perhaps more seriously, in the reduced performance and thus annual energy production (AEP) of the turbine.This thesis firstly presents the likelihood of hail events with respect to wind turbine locations, from an investigation of UK meteorological data. Three datasets were obtained: surface observations from UK-wide MIDAS stations, detailing back to 1949; as well as precipitation individual measurements from instruments located at CFARR and NERC facilities, also located in the UK. The prevalence of hail incidents is related to both onshore and offshore wind turbine operation.Particular attention was paid to the rotational speed of the wind turbine blades, which was determined to be a fundamental component of the energy associated with hail impact.From these impressions, an experimental campaign was carried out to investigate the effects on of repeated impact of simulated hail ice (SHI) on composite materials. Hailstones at four different diameters (5 mm, 10 mm, 15mm and 20mm) were fired at a range of velocities and for different numbers of impacts. Samples used for experimentation were manufactured from triaxial stitched glass fibre (0º, -45º, +45º) and epoxy resin. Damage was analysed qualitatively using scanning electron microscopy.A computational model was developed to compare the simulated damage of a singular hailstone impact to that of the experimental findings and examine other parameters not available in a practical setting. A survey of calculation methods was undertaken, to determine the elastic properties of the composite required prior to simulation. Threshold velocities were obtained for the onset of damage caused by singular impact of the different diameters of SHI.
Date of Award1 Oct 2016
LanguageEnglish
Awarding Institution
  • University Of Strathclyde
SponsorsEPSRC (Engineering and Physical Sciences Research Council)
SupervisorMargaret Stack (Supervisor) & David Nash (Supervisor)

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