2 research outputs found
Remote surface damage detection on rotor blades of operating wind turbines by means of infrared thermography
Wind turbines are constantly exposed to wind gusts, dirt
particles and precipitation. Depending on the site, surface defects on rotor
blades emerge from the first day of operation on. While erosion increases
quickly with time, even small surface defects can affect the performance of
the wind turbine. Consequently, there is demand for an easily
applicable remote monitoring method for rotor blades that is capable of
detecting surface defects at an early stage. In this work it is investigated if
infrared thermography (IRT) can meet these requirements by visualizing
differences in the thermal transport and the corresponding surface
temperature of the wall-bounded flow.Firstly, a validation of the IRT method compared to stereoscopic particle image velocimetry measurements is
performed comparing both types of experimental results for the boundary layer of a flat plate.
Then, the main characteristics of the flow in the wake of generic surface defects on different types
of lifting surfaces are studied both experimentally and numerically: temperature gradients behind protruding
surface defects on a flat plate and a DUÂ 91-W2-250 profile are studied by means of IRT.
The same is done with the wall shear stress from Reynolds-averaged Navier–Stokes simulations of a wind turbine blade.
It is consistently observed, both in the experiments and the simulations, that turbulent wedges are formed
on the flow downstream of generic surface defects. These wedges provide valuable information about the
kind of defects that generate them. At last, experimental and numerical performance measures are taken into
account for evaluating the aerodynamic impact of surface defects on rotor blades. We conclude that the IRT method
is a suitable remote monitoring technique for detecting surface defects on wind turbines at an early stage.</p