• Invited

Horizontal axis wind turbine testing at high Reynolds numbers

Mark A. Miller, Janik Kiefer, Carsten Westergaard, Martin O. L. Hansen, and Marcus Hultmark
Phys. Rev. Fluids 4, 110504 – Published 18 November 2019
An article within the collection: 2019 Invited Papers

Abstract

Detailed studies of modern large-scale wind turbines represent a significant challenge. The immense length scales characteristic of these machines, in combination with rotational effects, render numerical simulations and conventional wind tunnel tests unfeasible. Field experiments can give us important insight into the aerodynamics and operation, but they are always accompanied by large amounts of uncertainty, due to the changing nature of the inflow and the lack of accurate control of the test conditions. Here, a series of experiments is presented, using an alternative method that enables us to represent and study much of the physics governing the large-scale wind turbines in small-scale models. A specialized, compressed-air wind tunnel is used to achieve dynamic similarity with the field-scale, but under accurately controlled conditions of the laboratory. Power and thrust coefficients are investigated as a function of the Reynolds number up to ReD=14×106, at tip speed ratios representative of those typical in the field. A strong Reynolds number dependence is observed in the power coefficient, even at very high Reynolds numbers (well exceeding those occurring in most laboratory studies). We show that for an untripped rotor, the performance reaches a Reynolds number invariant state at Rec3.5×106, regardless of the tip speed ratio. The same model was also tested with scaled tripping devices, with a height of only 9μm, to study the effect of transition on the rotor performance. In the tripped case, the Reynolds number dependence was eliminated for all tested cases, suggesting that the state of the boundary layer is critical for correct predictions of rotor performance.

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  • Received 16 July 2019

DOI:https://doi.org/10.1103/PhysRevFluids.4.110504

©2019 American Physical Society

Physics Subject Headings (PhySH)

Fluid Dynamics

Collections

This article appears in the following collection:

2019 Invited Papers

Physical Review Fluids publishes a collection of papers associated with the invited talks presented at the 71st Annual Meeting of the APS Division of Fluid Dynamics.

Authors & Affiliations

Mark A. Miller1, Janik Kiefer2, Carsten Westergaard3, Martin O. L. Hansen2, and Marcus Hultmark1,*

  • 1Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544, USA
  • 2Department of Wind Energy, Technical University of Denmark, DK-2800 Lyngby, Denmark
  • 3Westergaard Solutions Inc., Houston, Texas 77006, USA

  • *hultmark@princeton.edu

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Issue

Vol. 4, Iss. 11 — November 2019

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