Load mitigation using slotted flaps in offshore wind turbines

Shilpa Thakur, K. A. Abhinav , Nilanjan Saha

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

This paper focuses on load mitigation by implementing controllable trailing-edge slotted flaps on the blades of an offshore wind turbine (OWT). The benchmark NREL 5 MW horizontal axis OWT is subjected to coupled stochastic aerodynamic-hydrodynamic analysis for obtaining the responses. The OWT is supported on three different fixed-bottom structures situated in various water depths. Blade element momentum (BEM) theory and Morison's equation are used to compute the aerodynamic and hydrodynamic loads, respectively. Presently, the load reduction obtained by means of the slotted flaps is regulated using an external dynamic link library considering the proportional-integral-derivative (PID) controller. BEM theory is presently modified to account for unsteady effects of flaps along the blade span. The present analysis results show reduction up to 20% in blade and tower loads for the turbine with different support structures on implementing controllable trailing edge flaps (TEFs). This study can form the basis for evaluating the performance of large-scale fixed OWT rotors.
LanguageEnglish
Article number061901
Number of pages10
JournalJournal of Offshore Mechanics and Arctic Engineering
Volume140
Issue number6
Early online date13 Jun 2018
DOIs
Publication statusPublished - 1 Dec 2018

Fingerprint

Offshore wind turbines
Flaps
Aerodynamics
Momentum
Hydrodynamics
Towers
Turbomachine blades
Turbines
Rotors
Derivatives
Controllers
Water

Keywords

  • design of offshore structures
  • dynamics of structures
  • ocean waves statistics
  • probabilistic models
  • spectral wave modeling

Cite this

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title = "Load mitigation using slotted flaps in offshore wind turbines",
abstract = "This paper focuses on load mitigation by implementing controllable trailing-edge slotted flaps on the blades of an offshore wind turbine (OWT). The benchmark NREL 5 MW horizontal axis OWT is subjected to coupled stochastic aerodynamic-hydrodynamic analysis for obtaining the responses. The OWT is supported on three different fixed-bottom structures situated in various water depths. Blade element momentum (BEM) theory and Morison's equation are used to compute the aerodynamic and hydrodynamic loads, respectively. Presently, the load reduction obtained by means of the slotted flaps is regulated using an external dynamic link library considering the proportional-integral-derivative (PID) controller. BEM theory is presently modified to account for unsteady effects of flaps along the blade span. The present analysis results show reduction up to 20{\%} in blade and tower loads for the turbine with different support structures on implementing controllable trailing edge flaps (TEFs). This study can form the basis for evaluating the performance of large-scale fixed OWT rotors.",
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Load mitigation using slotted flaps in offshore wind turbines. / Thakur, Shilpa; Abhinav , K. A.; Saha, Nilanjan.

In: Journal of Offshore Mechanics and Arctic Engineering, Vol. 140, No. 6, 061901, 01.12.2018.

Research output: Contribution to journalArticle

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AU - Abhinav , K. A.

AU - Saha, Nilanjan

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AB - This paper focuses on load mitigation by implementing controllable trailing-edge slotted flaps on the blades of an offshore wind turbine (OWT). The benchmark NREL 5 MW horizontal axis OWT is subjected to coupled stochastic aerodynamic-hydrodynamic analysis for obtaining the responses. The OWT is supported on three different fixed-bottom structures situated in various water depths. Blade element momentum (BEM) theory and Morison's equation are used to compute the aerodynamic and hydrodynamic loads, respectively. Presently, the load reduction obtained by means of the slotted flaps is regulated using an external dynamic link library considering the proportional-integral-derivative (PID) controller. BEM theory is presently modified to account for unsteady effects of flaps along the blade span. The present analysis results show reduction up to 20% in blade and tower loads for the turbine with different support structures on implementing controllable trailing edge flaps (TEFs). This study can form the basis for evaluating the performance of large-scale fixed OWT rotors.

KW - design of offshore structures

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