Abstract
Abstract. The measurement of deformation and vibration of wind turbine rotor blades in field tests is a substantial part of the validation of aeroelastic codes. This becomes highly important for modern rotors as the rotor size increases, which comes along with structural changes, resulting in very high flexibility and coupling between different vibration modes. However, performing full-scale field measurements for rotor blade deformation is not trivial and requires high temporal and spatial resolution. A promising deformation measurement technique is based on an optical method called digital image correlation (DIC). Recently, DIC measurements on a Siemens Gamesa SWT-4.0-130 test turbine were performed on the tip of all blades in combination with marker tracking at the hub for the first time with synchronised measurement of the inflow conditions by a ground-based lidar. As the turbine was additionally equipped with strain gauges in the blade root of all blades, the DIC results can be directly compared to the actual prevailing loads to validate the measurement method. In the end, an example for a comparison of the measured deformations and torsion with aeroelastic simulations is shown in the time and frequency domain. All in all, DIC shows very good agreement with comparative measurements and simulations, which shows that it is a suitable method for measurement of deformation and torsion of multi-megawatt wind turbine rotor blades.
Highlights
The increasing demand for a reduction in levelised cost of electricity (LCOE) of wind turbines leads to substantial changes in the design, operation, and reliability of wind turbines and plants (Dykes et al, 2019)
One time series of digital image correlation (DIC) measurements is compared to aeroelastic simulations of the turbine to demonstrate a way of experimentally validating rotor blade deformation and torsion based on DIC measurements
The DIC measurement duration was 5 min, and the simulations were conducted for a 10 min time series based on the statistics of the wind conditions during the corresponding time slot
Summary
The increasing demand for a reduction in levelised cost of electricity (LCOE) of wind turbines leads to substantial changes in the design, operation, and reliability of wind turbines and plants (Dykes et al, 2019). Optical markers are installed upright relative to the pressure side, and on these sections, the deformation and twist can be detected Another method called BladeVision was developed by SSB Wind Systems (Nidec SSB Wind Systems GmbH, 2020). A stereo camera system is installed in the area in front of the turbine, and random speckle patterns are applied on the blades’ pressure side On those sections where the pattern has been applied, the deformation and torsion of the rotor blade can be detected. One time series of DIC measurements is compared to aeroelastic simulations of the turbine to demonstrate a way of experimentally validating rotor blade deformation and torsion based on DIC measurements
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