Design and analysis of displacement models for modular horizontal wind turbine blade structure

Abstract

This study examined the normal, radial, axial and tangential loading cycles undergone by wind turbine rotor blades and their effects on the displacement of the blade structure. The rotor blade was modelled using Q Blade finite element sub module, which evaluated the loading cycles in terms of the forces induced on the blade at various frequencies through several complete revolution cycles (360o each cycle). At frequencies of 5 HZ, 23 Hz, 60 Hz, 124 Hz and 200 Hz, maximum strain deformation of 0.004, 0.04, 0.08, 0.14 and 0.24 were obtained, and geometry of the deformed blades were characterized by twisting and bending configuration. Maximum deflections from tangential loading increased from -0.55-1.2 mm, -0.39-1.6 mm from axial loading, -0.28-1.8 mmfrom radial loading and -0.01-2.3 mm from normal loading. From these deflection values, normal loading cycle would cause the highest level of structural damage on the rotor blade followed by radial, axial and tangential loading. Moreover, the strain deformations and deflections of the blade structure increased as the cycles of frequency increased.
 Keywords: Loading cycle, Wind turbine, Rotor blade, Frequency, Strain deformations, Deflections.