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Generation of Uniform Turbulence Profiles in the Wind Tunnel for Urban VAWT Testing

  • A. Carbó MolinaEmail author
  • G. Bartoli
  • T. De Troyer
Conference paper
Part of the Green Energy and Technology book series (GREEN)

Abstract

This study presents an innovative wind tunnel approach to evaluate the efficiency of Vertical-Axis Wind Turbines (VAWT) in turbulent flows, to study their integration in urban environments. The first part of the research is devoted to obtaining highly-turbulent wind profiles in the wind tunnel, with the use of different configurations of square grids. A careful study and validation of this technique is done, in order to obtain uniform wind conditions with the adequate values of turbulence intensity and length scales to model the urban flows. The set-up is used to test a H-Darrieus VAWT under values of turbulence over 5%, in comparison with the operation of the turbine under free stream. The preliminary results show that high levels of turbulence do have a significant effect in turbine performance, with increases reaching 15%. The errors in the measurements are analysed to identify the ways to improve the set-up and possible future developments.

Keywords

Turbulence Wind Tunnel Wind Energy VAWT 

List of Abbreviations

A

Frontal Area (m2)

b

Bar width (m)

c

Turbine blade chord (m)

CP

Power Coefficient (–)

CPfs

Maximum Power Coefficient at free stream conditions (–)

D

Diameter of the rotor (m)

f

Frequency (Hz)

H

Height of the rotor (m)

Iu

Intensity of Turbulence in wind direction (–)

Lux

Integral Length Scale of turbulence in wind direction (m)

M

Mesh size (m)

Q

Torque (Nm)

R

Turbine Radius (m)

U

Longitudinal wind speed (m/s)

u

Variable component of wind speed in wind direction (m/s)

V

Total wind speed (m/s)

v, w

Wind speed components transversal to wind direction (m/s)

x

Distance from grid (m)

λ

Tip Speed Ratio (–)

λfs

Optimal Tip Speed Ratio for the free stream case (–)

ρ

Density of air (kg/m3)

σx

Standard deviation of variable x

ω

Angular speed (s−1)

HAWT

Horizontal-Axis Wind Turbines

VAWT

Vertical-Axis Wind Turbines

Notes

Acknowledgements

The present research takes part in the European Innovative Training Network (ITN) AEOLUS4FUTURE “Efficient Harvesting of the Wind Energy”. The project is funded by the Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement No. 643167.

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Copyright information

© Springer International Publishing AG 2018

Authors and Affiliations

  1. 1.Department of Civil and Environmental EngineeringUniversity of FlorenceFlorenceItaly
  2. 2.Thermo and Fluid Dynamics (FLOW)Vrije Universiteit BrusselBrusselsBelgium

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