Analysis of the effect of a series of back twist blade configurations for an active pitch-to-stall floating offshore wind turbine
For a turbine mounted on a floating platform, extreme induced loads can be increased by up to 1.6 times those experienced by a turbine situated on a fixed base. If these loads cannot be reduced, towers must be strengthened which will result in increased costs and weight. These tower loads would be a...
| Published in: | Journal of Offshore Mechanics and Arctic Engineering |
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| Main Authors: | , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
2020
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| Subjects: | |
| Online Access: | https://strathprints.strath.ac.uk/72621/ https://strathprints.strath.ac.uk/72621/1/Ward_etal_JOMAE_2020_back_twist_blade_configurations_for_an_active_pitch_to_stall_floating_offshore_wind_turbine.pdf https://doi.org/10.1115/1.4046567 |
| Summary: | For a turbine mounted on a floating platform, extreme induced loads can be increased by up to 1.6 times those experienced by a turbine situated on a fixed base. If these loads cannot be reduced, towers must be strengthened which will result in increased costs and weight. These tower loads would be additionally exasperated for a pitch-to-feather controlled turbine by a phenomenon generally referred to as "negative damping," if it were not avoided. Preventing negative damping from occurring on a pitch-to-feather controlled floating platform negatively affects rotor speed control and regulated power performance. However, minimizing the blade bending moment response can result in a reduction in the tower fore-aft moment response, which can increase the tower life. A variable-speed, variable pitch-to-stall (VSVP-S) floating semi-submersible wind turbine, which does not suffer from the negative damping and hence provides a more regulated power output, is presented. This incorporates a back twist blade profile such that the blade twist, starting at the root, initially twists toward stall and, at some pre-determined "initiation" point, changes direction to twist back toward feather until the tip. Wind frequency weighting was applied to the tower axial fatigue life trends of different blade profiles and a preferred blade back twist profile was identified. This had a back twist angle of -3 deg and started at 87.5% along the blade length and achieved a 5.1% increase in the tower fatigue life. |
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