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Wind Energy Science The interactive open-access journal of the European Academy of Wind Energy
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https://doi.org/10.5194/wes-2019-107
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/wes-2019-107
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Submitted as: research article 10 Jan 2020

Submitted as: research article | 10 Jan 2020

Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Wind Energy Science (WES).

Characterization of a new perturbation system for gust generation: The Chopper

Ingrid Neunaber and Caroline Braud Ingrid Neunaber and Caroline Braud
  • LHEEA – Ecole Centrale Nantes, CNRS, 1 Rue de la Noë, 44321 Nantes, France

Abstract. We present a new system for the generation of rapid, strong flow disturbances in a wind tunnel that was recently installed at Ecole Centrale Nantes. The system is called the chopper, and it consists of a rotating bar cutting through the inlet of a wind tunnel test section, thus generating a gust that travels downstream. The flow generated by the chopper is investigated with respect to the rotational frequency using an array equipped with hot-wires that is traversed downstream the flow field. It is found that the gust can be described as a superposition of the mean gust velocity, an underlying gust shape and additional turbulence. Following this approach, the evolution of the mean gust velocity and turbulence intensity are presented, and the evolution of the underlying gust shape is explained. The turbulence is shown to be characterized by an integral length scale of approximately half the chopper blade width and a turbulence decay according to E(f) ∝ f−5/3.

Ingrid Neunaber and Caroline Braud
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Status: open (until 21 Feb 2020)
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Ingrid Neunaber and Caroline Braud
Ingrid Neunaber and Caroline Braud
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Short summary
Motivated by the need for wind turbine rotor blade tests in flows with atmospheric-like properties like e.g. gusts, we present a new setup to generate strong, rapid, turbulent gusts in a wind tunnel. The setup consists of a rotating bar that cuts through the inlet of the wind tunnel which generates the gust, and it is called the chopper. In this work, the flow generated by the chopper is characterized, and we show how the gust and its turbulence evolve downstream.
Motivated by the need for wind turbine rotor blade tests in flows with atmospheric-like...
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