How does turbulence change approaching a rotor?

Jakob Mann*, Alfredo Pena Diaz, Niels Troldborg, Søren Juhl Andersen

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

166 Downloads (Pure)

Abstract

For load calculations on wind turbines it is usually assumed that the turbulence approaching the rotor does not change its statistics as it goes through the induction zone. We investigate this assumption using a nacelle-mounted forward-looking pulsed lidar that measures low-frequency wind fluctuations simultaneously at distances between 0.5 and 3 rotor diameters upstream. The measurements show that below rated wind speed the low-frequency wind variance is reduced by up to 10 % at 0.5 rotor diameters upstream and above rated enhanced by up to 20 %. A quasi-steady model that takes into account the change in thrust coefficient with wind speed explains these variations partly. Large eddy simulations of turbulence approaching an actuator disk model of a rotor support the finding that the slope of the thrust curve influences the low-frequency fluctuations.
Original languageEnglish
JournalWind Energy Science
Volume3
Pages (from-to)293-300
ISSN2366-7443
DOIs
Publication statusPublished - 2018

Keywords

  • Renewable energy sources
  • TJ807-830

Cite this

@article{b50bf19f4d0f417e8ca1de565bff482a,
title = "How does turbulence change approaching a rotor?",
abstract = "For load calculations on wind turbines it is usually assumed that the turbulence approaching the rotor does not change its statistics as it goes through the induction zone. We investigate this assumption using a nacelle-mounted forward-looking pulsed lidar that measures low-frequency wind fluctuations simultaneously at distances between 0.5 and 3 rotor diameters upstream. The measurements show that below rated wind speed the low-frequency wind variance is reduced by up to 10 {\%} at 0.5 rotor diameters upstream and above rated enhanced by up to 20 {\%}. A quasi-steady model that takes into account the change in thrust coefficient with wind speed explains these variations partly. Large eddy simulations of turbulence approaching an actuator disk model of a rotor support the finding that the slope of the thrust curve influences the low-frequency fluctuations.",
keywords = "Renewable energy sources, TJ807-830",
author = "Jakob Mann and {Pena Diaz}, Alfredo and Niels Troldborg and Andersen, {S{\o}ren Juhl}",
year = "2018",
doi = "10.5194/wes-3-293-2018",
language = "English",
volume = "3",
pages = "293--300",
journal = "Wind Energy Science",
issn = "2366-7443",
publisher = "Copernicus GmbH",

}

How does turbulence change approaching a rotor? / Mann, Jakob; Pena Diaz, Alfredo; Troldborg, Niels; Andersen, Søren Juhl.

In: Wind Energy Science, Vol. 3, 2018, p. 293-300.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - How does turbulence change approaching a rotor?

AU - Mann, Jakob

AU - Pena Diaz, Alfredo

AU - Troldborg, Niels

AU - Andersen, Søren Juhl

PY - 2018

Y1 - 2018

N2 - For load calculations on wind turbines it is usually assumed that the turbulence approaching the rotor does not change its statistics as it goes through the induction zone. We investigate this assumption using a nacelle-mounted forward-looking pulsed lidar that measures low-frequency wind fluctuations simultaneously at distances between 0.5 and 3 rotor diameters upstream. The measurements show that below rated wind speed the low-frequency wind variance is reduced by up to 10 % at 0.5 rotor diameters upstream and above rated enhanced by up to 20 %. A quasi-steady model that takes into account the change in thrust coefficient with wind speed explains these variations partly. Large eddy simulations of turbulence approaching an actuator disk model of a rotor support the finding that the slope of the thrust curve influences the low-frequency fluctuations.

AB - For load calculations on wind turbines it is usually assumed that the turbulence approaching the rotor does not change its statistics as it goes through the induction zone. We investigate this assumption using a nacelle-mounted forward-looking pulsed lidar that measures low-frequency wind fluctuations simultaneously at distances between 0.5 and 3 rotor diameters upstream. The measurements show that below rated wind speed the low-frequency wind variance is reduced by up to 10 % at 0.5 rotor diameters upstream and above rated enhanced by up to 20 %. A quasi-steady model that takes into account the change in thrust coefficient with wind speed explains these variations partly. Large eddy simulations of turbulence approaching an actuator disk model of a rotor support the finding that the slope of the thrust curve influences the low-frequency fluctuations.

KW - Renewable energy sources

KW - TJ807-830

U2 - 10.5194/wes-3-293-2018

DO - 10.5194/wes-3-293-2018

M3 - Journal article

VL - 3

SP - 293

EP - 300

JO - Wind Energy Science

JF - Wind Energy Science

SN - 2366-7443

ER -